HD70-MechToElec

Change from Mechanical to Electronics

I set out to convert analog servo controls to digital controls and build a digital computer without knowing it.

            Home wired for electricity: My first knowledge of electricity began out of curiosity before I started school.  My father wired our home for electricity about the time I was born in 1923, he was on the “Power & Light” committee of the city council.  A new diesel engine had been installed in the power plant and he brought home a few boards from the shipping crates and made our kitchen table, with fold down leaves.  Before I was born he had mounted push button on off switches on the walls to turn on or off bare light bulbs that dangled at the end of long cloth wrapped twisted electrical cord.  The button with white insert pushed the light on and the black one to pushed the light off – later these terms would be flip, pull or turn the light on.  With the light on I could look up at the bulb filament when laying on my back on the living room rug.  The filament was too bright to keep in focus; several years later frosted light bulbs came out.  One fall evening I noticed the light go dim and bright, dim and bright – and at the same time heard the power plant diesel engines start; I ran outside to see the smoke rings that would puff from it’s distant exhaust stack. Years later in college I would find the way to bring on another alternating current power generator was to watch light bulbs go bright then dim to catch the moment they went dim (off) then close the connecting switch, locking on the extra power generator to the old.  We still kept the kerosene lamp handy as power could go out in stormy weather; due to power line failures. 

            Early Radio used batteries & ear phones:  My father first borrowed then bought a Radio before I started to kindergarten.  The first one used an A and B battery, and we used ear phones to listen to KMMJ the only radio in KS at Topeka. The A battery heated tube filaments, and the B battery, a collection of many 1.5 volt batteries connected in series, delivered about 150 vdc to power the vacuum tube plate element which attracted electrons boiled off the heated cathode element; something I learned much later.  Dad bought an Atwater Kent Radio with large vacuum tubes identified with single digit numbers. The radio was inside a metal case 18” wide, 30” long and 12” high with a large 12” inch diameter speaker that sat on top. The speaker had a permanent magnet consisting of broken magnet pieces tied by string to make an effective larger magnet.  This too I learned years later when I took it apart.

            Model T Electrical system.  My first personal experience with electricity came when I checked out the spark on my first Model-T.  I was shocked by high voltage from coils causing my reflexes to toss the screw driver some 50 feet back over my head – now that got my attention.

 

To cranking a Model-T you placed the thumb on the same side as fingers – it could kick back like a mule

 

The magneto, V magnets bolted to the fly wheel, generated electricity, supplying DC to the Ignition coils via a timer and on/off switch.

The coils, each in a small wood box, contained a core of iron wires wrapped in aluminum foil which served to magnetize the iron core and as an auto-transformer inductor to convert low voltage dc to high voltage dc to jump the spark plug gap.  On top of the box was a flapper arm that vibrated. When pulled down, by the magnetized core of iron wires, it cut off current to the coil, which reconnected when it sprung back up.  The term “engine tune up” came form setting the spring back amplitude of the vibrating switch that gave off a “singing sound” which was “tuned” until it vibrated at the most effective frequency.  Later vacuum tube equivalents were called oscillators (to generate radio carrier waves) & semiconductor equivalents were called multi-vibrators. The timer, a rolling wheel in a cup at the front of the engine with alternate cooper-insulator segments, connected a given coil to ground, each coil was selected in it’s turn.

When the car would not start it was necessary to make sure you had gas and spark. By placing a screwdriver on a spark plug and a gap to engine block, which was at electrical ground, you could see a spark jump the gap if ignition coils worked OK.  I had used a screw driver with wooden handle from a Model-A tool kit to check the spark.  On that kind of screwdriver the metal went all the way through the wood handle so it could be pounded with a hammer.  That metal end caused me to be part of the high voltage to ground path – the high voltage gave my muscles a kick and the screwdriver was flung back over my head – a lesson remembered.

 

Brake, Reverse & Low peddles squeezed bands to hold transmission gearing for desired result.

If the low band went out, and not pull up a hill, you could always turn about and back up.

At full throttle it would go about 40 mph, car below right with over size rear truck tires could go 45 mph.

  

I experimented with magnets, to see a flux field, and test attraction & repulsion

 

Diagram at left is a good representation of Model-T coil & timer system.  Right hand rule is worth remembering

   

Voltage boost (or drop) with turns ratio on transformer has many applications like dropping voltage on resident power poles.

The output of a Model-T generator was set by adjusting a third brush.

  

              Same as above right                                    Same as below right       right: Minuteman missile solution to Contact problem below

 

Later Model-T’s had starters, more heavy duty than the generator, with engage, disengage to fly wheel drive.

Later cars used one transformer coil with distribution of the high voltage to spark plug.

Minuteman Missile pump motors rotated at 30,000 rpm, requiring piano wire wrapped commutators to hold segments in place.

  

WW II era cars used cam driven points, part of the distributor, which had to be adjusted & gap set for proper timing.

Points and capacitors had to be replaced periodically as breaking a connection “pulls an arc” causing damage to points.

Use of semi conductors provided solutions to problems like this; up two right

            My buddy “Doc” Hughes and I drove my Model-T below to McCook NB for a band contest and fair.  We discovered our generator was not working when we arrived. We had to get it fixed so we could have lights to come back at night.  Knowing nothing about how it worked we stopped at a shop along the highway and asked a mechanic what might be wrong.  He made a quick check and said the generator adjustment was shorted out.  Taking sympathy he said he’d fix it for $1.00.  That would take most of our spending money, a gallon of gas cost 13 cents at the time.  We thanked him and said we’d see if we could find some buddies with some money.  We drove up main street to the city park and decided to take the generator apart and see if we could find and fix the problem.  Sure enough, insulation on the adjustment arm for the third brush had worn through.  I walked down town and bought a 5 cent roll of “friction tape”, we tore off a piece to fit over the missing insulation and soon had it generating electricity.  That night we had passengers in the car, on the running boards on the front fenders – they had to jump off and help push up hill’s be we made it back to Oberlin with flying spirits.

  

Engine driven magnetos generated their own electricity, they were used, redundantly,  on all aircraft engines. At right is one, of two, distributors on a B-29 engine.

 

Dad’s “Ford black” 1924 “company car”      My red white blue 1928 Model-T (fitted with radio) was an Aircraft Maintenance Trainer

The magneto did not work on most junked Model-Ts, later models used a battery under the floor board.

            My fascination with rebuilding old cars was the incentive to choose mechanical engineering when I went off to college at Kansas State Manhattan KS, a Land Grant School with ROTC; all engineers were in Coast Artillery.  This back ground came in handy in Airplane Mechanic School and selection for Engineering Cadet school and eventual commission as an Engineering Officer for aircraft maintenance.

            Though I learned much from the Model-Ts, and had taken Physics and Chemistry in high school, and had completed first semester sophomore college physics, which did not include electrical circuits.  I had learned a lot about electrical systems while going to aircraft maintenance training , then as an instructor, followed by training at Yale as an aircraft maintenance engineering officer.  While stationed in Lincoln NB, I had purchased books on electrical engineering at a used book store.  I had acquired much practical application information, but not but only limited knowledge applicable to design.  I knew DC electricity quite well but still had a lot to learn about AC, except for practical wall plug stuff.  On the return trip home aboard the transport I found a paper back version of my Hausmann and Slack college physics book.  I poured over that by the hour, knowing that’s where my formal education would pick up.  extracts from that electrical section follow this story about reactivating electrical power to the flight line late 1945.  

            Diesel Power Plant:  As an index to when I knew what, I recalled two fellows finding me on the flight line, asking for me by name, to help them start the 19th Bomb Group flight line electrical power plant.  We had just found ourselves without electrical power.  The second batch of experienced maintenance personnel had been abruptly shipped home and I was taking and informal inventory of experienced personnel remaining, we were down to a precious few.  It as no surprise that flight line electrical power had gone out, I was pleased that someone had sent people to get it up and running.  I was age 21 and these fellows were about my age, and I assumed they had some kind of qualification to have been assigned to this task.

 

 

            I said, OK get in the Jeep and we will go have a look, do you know where it is?  They said it was across from the main service center in a Quanset building; we found the one with power lines terminating there and entered.  There was a huge diesel engine, with a large electrical generator at the far end and plus a large board of switches on the far wall.  We walked down to have a look at the switch panel.  I spoke aloud as I thought, telling them I didn’t know anything about this so lets have a look.  I said, lets pull all the large knife throw switches to OFF, to remove any load.  I then looked at a large generator direct connected to the diesel and a gasoline engine with battery, starter button at the side with large cast iron lever with CLUCH cast on the handle.  I said OK, this is where we start the thing; now lets trace down the fuel supply.  We followed a galvanize pipe to an outside fuel tank, with a turned off hand valve where it extended to the huge engine.

            I opened the valve and said, I think we now have fuel, if we can get it to start.  I knew a diesel engine did not use spark plugs, so went to the gasoline engine, turned on the ignition key and pushed on the starter button: varoom and it was running at a steady smooth rate.  I everything seemed ready so I decided it was time to throw the clutch lever. I did and was met with loud clatter and pounding  -- after a few moments pulled the clutch to disengage. I had been startled by the clamor and noise.  It was a huge engine and inside a tin building.

            I said to myself, you chickened out too soon. Recalling fellows start diesels when building the highway back home, those too had a clattering clamored when first starting.  So again I engaged the clutch, determined to keep the gasoline engine engaged and turning the diesel. 

            Abruptly the noise quieted down and that big monster was at peace with itself, humming away, ready to carry a load.  I looked about and saw the guys grinning ear to ear.  I shut down the gasoline engine and said OK now lets apply power to the flight line. At the big power panes we lifted and shoved each large knife switch to ON and checked the instruments on the wall. We were back in business.  I said to the fellows, OK you now know how it’s done, your on your own now, and by the way there is probably a manual somewhere in that desk telling how this is to be done.

            At the time I knew that generator was actually a three phase alternator, probably connected in Y  with the center node connected to ground and each of arms delivering 110 volts to ground, fanning out to power the flight line.  I knew that a volt meter reading from one arm to the other would read 220 VAC.  I knew more than I realized but still had so much to learn.  It’s one thing to use instruments and take readings and quite another to understand the workings of the instrument and system.

 

 

Extracts from “Elements of Electrical Engineering” by Cook  1941 text book

  

Solenoids are good for remote or controlled operations; when your washing machine emits CHUNK it’s a solenoid at work.

 

Electrical to Mechanical                                                                           Mechanical to Electrical

 

               Remotely controlled power switch                                                               Bomb Shelter Test Facility, # 1 control room

I took the facility power switch apart and found how it operated, then placed the remote control switch on the control panel above

  

               Solenoid operated hydraulic valve                                                             Oven vent control motor

  

Remotely controlled TV and Mirrors – using two WW II camera control motors

 

Saturable control of heater element inside vacuum test chamber above; used for Navaho Missile testing.

 

Brushes on commutator deliver DC out.                                        Brushes on slip rings deliver AC out

  

From simple to complex pole windings

  

Early large motors used “ring” oiled shaft sleeve bearings; typical prior to ball and roller bearings.

            Before I started grade school I was fascinated by what went on at the Mill.  I would walk over and watch the workmen start the big single piston engine that drove a huge flywheel.  On the side of it was a flat pulley from which they would connect a belt to a larger pulley that drive “line shafting” down through the plant. The line shafting passed through “pillow block” bearings.  After I went to work for the company it was my job to sometimes check the oil in the pillow blocks.  A metal ring that was rotated as the shaft turned, moving to dip into an oil pool and lift oil to keep the sleeve shaft bearing oiled. It was simple and reliable.

            The summer of my freshman year in college the Mill sent me to am old grain elevator in Nebraska to make repairs, turn over bins of wheat while adding chemicals to kill weevil, and add new wheat to the bins.  Returning to the elevator I noticed smoke coming out of the cupola at the top, having watched the mill burn down before I started kindergarten I knew this was real trouble.  I ran all out and climbed the ladder to the top finding the wooden motor pulley (like the one above) on fire.  Rat holes had leaked, over filling buckets on the elevating belt causing the motor pulley to slip on the drive belt.  The old wood structure was very dry, there was no water in the water barrels, I grabbed a near by scoop and dumped wheat on the file till I smothered it.  The above motor image brought memories front and center. 

 

Right: (a) is cumulative and (b) is differential compound

Series wound motors have great starting power, auto starters are series wound, they will increase in speed until slowed by the load.  

 

Household power viewed on an oscilloscope displays as a 60 cps sine wave.

  

Current through a resistance is in phase with voltage, through an Inductor it leads voltage, through a capacitor it lags voltage.

When in parallel, phase of the current is determined by the combine effect of capacitance & Inductance.

Radio stations are selected by “tuning” capacitance & inductance to pass the frequency that fits.

 

 

Most households are delivered two phased plus ground.  Industrial site receive all phases

Most household motors are single phase, and use capacitance assisted start.

Most house hold power panels alternate phases so adjacent fuses can be ganged to handle 220 volts for stoves and ovens.

  

Squirrel cage motors are mechanically very simple and reliable.  They have poor starting torque, but suitable for fans.  They run at fixed rpm set by the 60 cycle power source frequency.

Variable speed drive right, motor at bottom, was hard pressed to drive the 8 gpm 3000 psi pump in the oven.

            Household Wiring:  It was necessary to move and reconnect the power box for a do-it-yourself addition to our CA home, in accordance with building codes.  This involved two phase wiring.  All went well, I believe the power company people were a bit surprised to find this being undertaken by the home owner.  Previously I had also made a plan for rewiring power to and about the bomb shelter test lab in Downey CA.  Power to the entire plant passed through a near by manhole, which got wet an sometimes cause the loss of plant power during a heavy rain.  I had requested plant engineering to redo the test facility wiring while extending the roof over the manhole and modifying plant wiring.  The plant engineer assigned to us would come take a look, shake his head and nothing would happen.  So I sat down at my desk and using a quadrille pad revised the wiring, showing old and new.  I took my design to the head of plant engineering, expecting them to have it redrawn in accordance with their methodology.  Rather than redraw it, they sent my drawing to an outside contractor to implement.  The outside contractor bolted an electric motor driven hole saw cutter to the 15 inch thick steel reinforced bomb shelter wall and simply cut an 8” diameter hole.  The next day they mounted a large circuit breaker panel system to which they brought in 700 amps of 3 phase 440 volt AC power and delivered it the respective test cells.  I had wondered how they were going to do this as previously plant engineering has sent fellows to jack hammer a hole through the wall.  They made lots of dust but could not “hammer” through 1.5 inch diameter iron reinforcing bar. I had confidence I knew how to handle electrical power.  

            Household power is shipped from the source to destination at high voltage then reduced locally through power company owned transformers.  Typically three wires go from the power pole to the power box on the house: ground and two 110 V lines.  These connect to the fuse panel and fan out through the house.  Lights and wall plugs are place on different circuit breakers, such that if one goes out the other is still available in a given room.  Stove and ovens are supplied through adjacent circuit breakers, mechanically linked to “through” as one.  Adjacent fuse locations have a different power phase.

            Power companies try to average out the loads on each of the three phases they deliver.  If not the “Power Factor” is less than ideal causing an energy loss due to the inefficiency. 

Ohms Law for DC Circuits  (Battery source)

Known

I= Current amperes

R=Resistance ohms

E=Volts

P=Power watts

I & R

 

 

E=I*R

P=I2*R

I & E

 

R=E/I

 

P=E*I

I & P

 

R=P/I2

E=P/I

 

R & E

I=E/R

 

 

P=E2/R

R & P

I=(P/R)1/2

 

E=(P*R)1/2

 

E & P

P/E

E2/P

 

 

Ohms Law for AC Circuits  (Wall plug source)

Known

I= Current

Z=Impedance

E=Voltage

P=Power

I & Z

 

 

E=I*Z

P=I2*Z cos θ

I & E

 

R=E/I

 

P=I*E cos θ

I & P

 

R=P/I2 cos θ

E=P/I cos θ

 

Z & E

I=E/Z

 

 

P=E2cos θ/Z

Z & P

I=(P/Zcos θ)1/2

 

E=(P*Z/cos θ)1/2

 

Z & P

P/Ecos θ

E2cos θ/P

 

 

 θ phase angle in degrees by which current leads voltage for capacitance and lags for inductance, L is Inductance in henries, C is capacitance in farads.  Z is AC impedance, a function of resistance, capacitance and inductance 

 

Volt-Ohm meter                                            Ammeter

            Instruments: The volt-ohmmeter was standard equipment for all people servicing electrical equipment.  I added an Ammeter to my set of tools, finding it very helpful in finding and fixing problems in the bombshelter test lab.  Pressing the side opens the jaws so they can enclose an AC line when closed.  Like magic, you can read how many amps are flowing through the wire.  When testing electronics equipment the Volt Ohmmeter cannot be used as it becomes part of the circuit being tested.  Vacuum Tube Voltmeters were used for that.  More recently such instruments have been transistorized.

            Generators to Alternators: Prior semi conductors cars used generators to produced Direct Current. The advent of semiconductors made it possible to produce AC and rectify it diodes built in as part of the alternator.  This was a much more reliable and cost effective way; it still provided DC to charge batteries and operate the cars DC systems. 

            Semiconductor Ignition:  As soon as semiconductors became reliable and low cost they were incorporated to perform electronic ignition.  The problem with point went away.  The spark plugs on my 1986 T-bird lasted 130,000 miles with being removed for other reasons.  The plugs had never been cleaned or re-gapped. For someone used to periodically repeating this task it seemed unbelievable  

            Reading about Radio: My acquaintance with electronics began in WW II after I completed training as an aircraft maintenance engineering officer.  I was already acquainted with standard electrical terms as defined in the above table.  I bought a book to read while being shipped by train from FL to CA, the book, cover below, was on radio and how it works.  Later, when overseas, I managed to repair my personal radio which had been crushed in my barracks bag.

 

 

B-29s used a lot of electronics, with which I was only marginally involved, though I did learn much talking with barracks mates Radio officer Brownell & Radar officer Smith, a graduate chemical engineer.

            My radio was based on the above design and image where the speaker used an electromagnet, which also served as a filter for the AC to DC power supply.  I replaced the damaged speaker with a permanent magnet speaker but found I needed to continue to use the speaker coil as a filter to smooth the DC power extracted from AC power. Having read the book before going overseas I could at least recognize the parts and have a mild appreciation for what they did.  Brownell & Smitty explained what I had done. The tube numbers 12+12+12+50+35=121 are the voltage drop of each filament used to heat the cathode and boil off electrons, controlled by grids, when sucked to the high voltage plate.  Each stage of amplification is electrically separated but signal coupled by IF (Intermediate Frequency) carrier wave transformers, the square cans in above image were tuned by a slug, not shown, for best coupling.  This method of flux coupling would later be used make position measuring transducers for aircraft and missiles.

            Cascading Amplifiers: It’s important to understand the need for electrically isolating amplification stages.  When going upward on a piano, you move to the next octave.  A given tube or transistor amplifier only has “one octave” , from low to high system voltage, the signal being amplified must be passed from one amplifier to the next by inductance or capacitance; an isolation transformer for tubes or a capacitor for transistors. Radio signal are superimposed on a carrier wave by Amplitude Modulation of Frequency Modulation.  Though seemingly complex at first, it falls into place once you understand the concept.

            While in service I had been trained in school and on the job as an enlisted Mechanic and as Engineering Officer on aircraft maintenance. This included knowledge of WW II technology instrumentation.  The B-29 had a gyro stabilized “flux gate” compass out in the left wing whose position was read by a 3 phase Selson movement to the Navigators station then forwarded with a Magneson movement to Pilot and CoPilot.  These were low level signals and not really understood at the time.  To solve signal problems we were having I had the fellows use belt buckle polish to clean pins at a disconnect in the Bombay, which had been exposed as a test point – this extra cleaning and fitting solved our problem.  Years later working on the C-17 cargo plane I read literature by Honeywell on how low level signal contact points often need a few milliamps of current flow to sustain a connection.  The B-26 was loaded with 3 phase electrical sensors as instrumentation.  In Java & Australia in 1942 19th BG mechanics  built their own test equipment from parts salvaged from crashed airplanes.  You can’t “see” electricity so you must know how to create it for stimuli and measure it’s response.  Though not electronic, I gained much insight by having to be able to draw diagrams from memory on how voltage regulators, turbo-supercharger controls, etc worked.  Though tremendous strides had been made, many of the methods were in the growing pains of innovation and development.  Remote reading of cylinder head temperatures was very difficult.  Carburetors were really mechanical computers. New air position indicators were exceptionally clever mechanical devices for doing things greatly simplified later by electronics.

  

            After WW II I returned and finished mechanical engineering, before accepting a job as a Civil Engineer with the KS highway commission were I had previously worked summers as an Engineering Aid while finishing school.  I had to teach myself how to survey, and married neighbor girl, my sisters classmate, during my first year on the job.

 

When the Korean war broke out I went to work for General Motors KC KS as a Process Engineer on tooling for fabrication and assembly of the airframe for an F-84F fighter.  When that program ended I was transferred to a GM automotive assembly plant in CA, during which I met a fellow I’d worked with in KC, who was then working for North American Aviation.  He set up an interview with his boss and I went to work for North American in Downey assigned to Flight Controls for missiles.

 

The electronics test equipment was critical for testing electronically controlled servo actuators used to move flight control surfaces on this unmanned transcontinental missile under inertial guidance & computer control.

 

Data for plotting Amplitude Ratio & Phase shift was gathered by setting an amplitude command with middle black panel at a low frequency set with the large left middle knob.  An hour glass image on the oscilloscope displayed commanded position vs actual position.  The large right knob was turned until a perfect hour glass image was formed, the reading on that dial was the phase shift for the commanded frequency to match the feedback.  As frequency was increased the amplitude dropped and phase shift increased.  This test could prove if the system was working properly.

I was caused to run such a test my first week there – the test failed, after 3 days of intense study I determine why.

The “Bomb Shelter” on the right side was hauled up Lakewood Ave from Douglas to the North American Downey plant.  The concrete slab and oven test cells were added. Larry Hein is shown inside the bomb shelter in a control room equipped with closed circuit TV (later replaced with mirrors) to see tests inside the test cell. Beyond the 2” thick glass window, mounted in a 15” thick reinforced concrete wall is an oven that heated to 1100 degrees F, then in use to test a “glide brake actuator” which was to work after mach 3.5 Navaho Missile flight powered by Ram Jet completed an intercontinental flight. This was indeed cutting edge stuff, a demanding learning experience.

            Hi Temperature Test Lab Remote Controls:  I had been hired to help set up this lab, brick and mortar was going up while I helped check out the first Navaho booster, previously described.  It was necessary to use mechanical, electrical and electronic means for remote control of systems under test.  After we had it up and running we were asked to test a hydraulic controls system for Johns Hopkins Lab who were advisors to the Navy and experimenting with an “acceleration switching valve”. Their valve, dithering at about 128 cps set up a vibration in the associated hydraulic system – from this I learned a dithering process would not work at such a low frequency, and later avoided this problem.

Bob Kelley, an ex Ham operator and self taught electronics guy was assigned to help build electronics for early Minuteman servo actuators .  When I’d asked for help Bob had been assigned to me, as he did not have an engineering degree.  My, what a god send, Bob had our simulated Minuteman electronics working before graduate engineers did the real thing.  They were coming to Bob to find out how he was solving certain problems.  The Minuteman was a solid propellant vehicle and didn’t have a shaft driven supply of electricity.  Minuteman used battery power and to create alternating current for transformers you had to chop DC; the resultant “square” waves caused all kinds of “noise” problems.  I listened as Bob told the fellows the servo valves cannot respond to the high frequency noise from the 6 hz position transducer square wave excitation; so don’t worry about filtering it out.  From this I knew high frequency “noise” on a command is integrated by the servo control valve as a composite average signal.  This was useful to know later on.

Bob helped me become acquainted with electronics by suggesting, then advising me, on how to build an all transistor HiFi Amplifier with out the need for large output transformers as required for vacuum tube operation.  For that experiement I made my own electronics test equipment by building kits; a Vacuum Tube Volt meter, Oscilloscope, Signal Generator, etc to fine tune my “all transistor” HiFi set.  This was excellent back ground experience for what was ahead.

 

The most advanced vacuum tubes at the start of WW II, were those at far left.  During WW II they became more sophisticated as shown by the large tube at the center, after WW II tubes were smaller as those by metal clip on shield to the right, followed about 1954 with “peanut” tubes as shown far right..  The Navaho missile system used peanut tubes, carefully shielded and potted in place to withstand severe vibration.  Peanut tubes served as hydraulic servo valve coil drivers and as demodulator rectifiers for position transducers.

 

Left: Home made HiFi cabinet to hold Tape Recorder left, AM-FM Tuner plus Amplifier center and LP phono player right with speakers on each side of storage.    Right: Heath Kit Vacuum tube HiFi amplifier.

 

I soon joined others reading information on how transistors worked.  There were germanium and silicon transistors sprinkled with rare earth atoms to become N or P kinds which were then connected where electron flow was from P to N when enabled.  Initially there was much confusion, where physics professors wrote of the flow of “holes” whereas technician instruction was written as electron flow.  A bit like the old battery problem.  It’s known that electrons flow from negative to positive, but mechanics think of it as from plus to negative.  It was not necessary to know how they worked inside if you could learn how to use them.

The semiconductor industry made available booklets and experimental projects for use in learning how these worked.

 

1956 home design and assembly of “All Transistor” Hi Fi Amplifier;  now in Museum Oberlin KS, with dual channel power amplifiers plus signal shaping preamplifiers with multiple selectable input options.

            This endeavor provided much hands on experience using instruments to bias transistors for hi fi operation.  It was “tuned” (bias set) using square wave rather than less demanding sine wave.

  

Photo on card table right, made from yard tree and plant trimmings

            At this time I experimented with a simple radio encased in a jar, which could readily drive a small speaker for music while I worked in my garage.  The tiny full transistor with IF transformers at right sat unfinished for about a year.  I took the IF cans apart and found the wiring and diagram on the case did not match. When corrected it worked fine.

 

Minuteman I used Inertial Guidance and was the first to use all transistor electronics.

Work in the Bomb Shelter demanded that I learn and know the symbols, electronic terms and measurements.

            Intermittent failures:  Minuteman I experienced some random failures which were eventually traced to two things.  Flakes inside transistor packaging could come loose and cause intermittent failures.  An electronics box could check OK, move it to a near by work bench and it would fail. Once the cause was discovered an all out Reliability program was initiated, special lines and procedures used at suppliers and a defined set of MM parts and procedures established.  This more than anything else brought about a huge increase in commercial parts reliability as well. It made further integration possible.

            Missile Ground “holy point”  It was found the system of vehicle electronics used multiple ground points.  This was solved by defining how things were to be grounded and all connected to a single point at the front of the missile, the “holy point”.

 

 

            I had read about setting the bias on vacuum tubes but didn’t know it’s meaning.  My mother used the word when sewing, but I didn’t understand it’s electronic meaning.  When setting up the transistor hifi preamplifiers I applied a sine or square wave signal to the input and read the output result on an oscilloscope.  In the above figure current flows through the transistor collector at the top, under the control of a middle gate, out the emitter through a resistor to ground.  This is like water through a faucet with the base being the handle. The resistor on the emitter leg lifts (bias) the output signal above ground so it can swing plus and minus.  The two 10K resistors connected to the base are base bias resistors which provide a mid point about which the input signal can swing.  It was critical that these be set properly so the command could be amplified without being clipped off at the top or bottom.

A friend of mine Fritz Gardner, a graduate electrical engineer had been assigned to the Army Signal Corps from ROTC.  He was then assigned to the Air Corps at Wright Field to look into problems they were having with the new electronically controlled superchargers on B-17’s.  Honeywell had designed the controlling electronics which used vacuum tubes.  He chuckled when he told me it must have been designed by mechanical engineers who did not know about operation of amplifier vacuum tubes.  There was no bias resistor to the amplifier grid.  They had been “cherry picking” tubes till they got one to work, but after a while it’s natural bias would change.  Once properly biased the amplifier worked fine.  Doing 19th BG history I was read of how they were having supercharger problems on B-17s sent to haul MacArthur out of Mindanao. The pilot Harl Pease, later awarded the medal of honor, had no way of knowing why his supercharger was not working properly.

Emil Kohler helping with our digital control, taught me how to think about commanding transistors on or off.  You “sourced” current to the Base to turn them full ON and would “sink” current from the base to turn them full OFF.  Bipolar Transistors are “flow controlled” valves.

Emil also emphasized that Transistors operating in the analog mode heat,  while those operating in a digital mode they do not heat.  When a power transistor it is working like a variable resistor it is throttling energy and heats.  When full off there is no current flow, when full on there is no resistance, thus no heating.  I later used this knowledge to make a servo valve driver using a small RCA 4016 transmission gate chip.

Heat Transformer:  Before leaving the test lab I designed a system using connected hydraulic cylinders and the principle of an electric transformer to isolate the hot inside and oven environment from the cool outside environment.  The push-pull cycled hot actuator delivered AC hydraulic power, which with check valves was rectified to DC hydraulic power, with a cool outside accumulator as a “capacitor” and pressure drop valve “resistor” filtered the pulsed DC hydraulics to smooth flow.  I built such a system and it worked.  The intent of this was to eliminate the need for hydraulic heat exchanger systems for B-70 supersonic bomber testing.  The US cancelled the B-70 program and replaced that with Minuteman solid propellant missiles launched from silos.  Mixing of electrical and mechanical concepts proved helpful in many ways.

Two B-70’s were built, the first crashed and second is at Dayton Ohio.

Operational Amplifiers:  I was asked by Art Greer to look into the idea of designing an electronically controlled load simulator for testing Minuteman hydraulic servos, as we had no idea what kind of loads we might encounter.  I had been studying Servo Controls textbooks, mostly to be able to communicate with those who ran computer simulation studies.   I knew that loads can be expressed as a function of:  position, velocity and acceleration; where the total load is the summation of some coefficient time each of these kinds of loads.  When I started to design such a system I was told they were going to have to move me from the test lab to other work, and that I should buy and not try to build such a system

I knew we could use position feedback from the actuator under test, then electronically convert position to velocity and velocity to acceleration, where velocity is the rate of change in position and acceleration is the rate of change in velocity.  The total load would be the sum of these terms, and associated coefficients applied to them. I knew the computer simulation labs did such things so I wrote a specification of what we needed, gave it Purchasing and they had a very capable fellow come see me.  The fellow left me a booklet on Philbrick brand  Operational Amplifiers etc. The test console was designed and built but never used.  Art Greer was moved to Project Office & I was assigned as lead engineer on Minuteman I Flight control hydraulics.

            Missing ground connection: Prior to the above I had been move from the test lab to be lead engineer for flight control hydraulic components.  One day Dan Hoskinson, an electronics design engineer friend of mine came by suggesting it was time for a cup of coffee, expressing exasperation with what he was doing.  I asked what’s wrong. Dan said we have two electronics cards, that work fine alone but not when connected, as they are supposed to be.  Walking back with cups of coffee I asked if he had a diagram?  He said sure, got it and showed it to me, I looked over how the two connected together and said Dan, you’ve connected the signal wires, but these do not have a common ground connection.  I’ll bet if you connect the two grounds they will work.  I can still see the expression on his face and how his jaw worked as if to speak.  Then he said, Damn how could we have missed that, it’s so obvious.    

            I would encounter this problem in a big, but different way, during Minuteman III. 

Minuteman I Flight Control used a digital computer, primarily due to the insistence of Elliott Buxton. This electronics consisted of individual transistors and associated resistors and capacitors to be mounted on a removable card, accessible by removing missile skin. This was similar to technology then used by IBM, discrete logic parts on a removable card.

 

Right: Nozzle Control loop closure down stage

 Minuteman I hydraulic pumps were driven by electric motors.  They ran at about 30,000 rpm, and their armatures could not be cooled, they were in danger of burning out and required long lengths of heavy cooper cable for ground check out.

Warm gas solid propellant power:  I later experimented with the idea of driving the pumps with a hydraulic motor driven by solid propellant “warm gas” (2000 F). Vickers was using this concept on Douglas Sky Bolt missile program where they powered pumps using a warm gas driven hydraulic pump.  I arranged for building a gas generator and ordering a gas driven pump from Vickers who were building our Minuteman hydraulic pumps.  The hardware arrived after I was assigned to a new task.

 

Vickers MM I, Stage I pump left, Stage III cut away right.

            Although the motors were equipped with electrical noise filters, the box on top, they still radiated a lot of high frequency noise. The pumps were a very clever design where the pump was inside a stainless steel bellows oil reservoir. Purpura and Greer working with Vickers came up with this design.

            The servo actuators were also a clever design where the Servo Valve was a round module, believed to be more reliable than face seals.  The position transducer fit inside the piston as compared to strap on models used before. These transducers had been designed by Gary Collins former employee who play cards with the fellows who complained their conventional variable resistor designs could not survive the severe vibration environment.  Gary, a Radar Engineer, had an idea on how to build a better device obtained hydraulic tubing from the fellows and wound a coil about an inner tube, covered it with an outer tube and placed a moving slug inside.  The output of the specially wound transformer would deliver plus or minus voltage based on the position of the slug.

Typical Ling Temco Vaught  Minuteman I Servo Actuator

 

Photo of Collins position transducer left, with square wave excitation and output

Collins had developed these using sine wave for the Navaho program, and was the only contractor who could produce a linear output when using chopped battery DC for excitation.  At one time he was the only producer for the devices for the entire aircraft industry who immediately change to them as more reliable.  He built them in a home near the plant, setting up manufacturing in the living room and using the kitchen as an experimental lab – Sub Contracts almost didn’t approve him as a sub contractor on the important Minuteman program because he didn’t fit the conventional business mode. These were called LVDT = Linear Voltage Differential Transformers, now standard throughout the aerospace industry.

Prior Navaho missiles used a similar rotary device & one of my first assignments was to use a Vacuum Tube Voltmeter to set NULL on a unit in the factory. A conventional voltmeter becomes a part of the vehicle circuit which invalidates the reading.  A vacuum tube voltmeter applies the signal to be measure to the vacuum tube grid, thus isolating it from the vehicle circuit.  The transducer output goes from a high plus to near zero (null) then high minus, as if the signal span was a  V .  The lowest point is called the Null, representing the center of the actuator stroke. 

 

Conventional diode rectifier left      Standard Summing junction loop closure right.

It was necessary to use Demodulators to convert AC to DC.  This confused me at first until I found that diodes in full wave rectifiers, as shown above, have a voltage drop, which is not acceptable for low voltage “instrument” readings.  In a Demodulator, diodes are replaced by transistor switches, commanded by the excitation frequency, the commanded on transistors result in voltage drop, when rectifying the signal.

Servo Actuator controls terms are: Feedback, Summing Junction, Error Signal & Fwd Loop Gain initially new to me.  A servo actuator, like the one shown above, includes an electronically controlled servo valve that ports hydraulic fluid to extend or retract the actuator piston and a negative feedback transducer, that measures the position of the actuator.  The Guidance and Control system issues a position command telling the attitude control servo actuator where it’s to go.  The analog summing junction is where two resistors come together producing an error at the summing junction node. The error being the command minus the feedback.   The error is amplified, by an amount called the forward loop gain; with the output going to the servo valve coil.   When the feedback cancels the command, the actuator has reached the intended position, there is no error, thus no commanded motion.  If the error signal is amplified too much, hi fwd loop gain, the actuator will over respond which can lead to instability, conversely under gain can lead to sluggishness.  The amount of the commanded error controls the rate of the response.   I would later perform these functions with digital devices. 

Analog controls electronic was inside the center section – the unit is covered with ablative rubber material for thermal protection.

 Image Deleted, text retained 

An Igniter at the front end blasted burning solid propellant down the center core to ignite the main propellant.  The pattern provided burn surfaces on pie shaped pieces for rapid burning.  The “throat” at the entrance into the exhaust nozzle chokes flow to sonic velocity.  The hot gassed expands down to the exit plane of the nozzle imparting a forward thrust victor against the sided of the nozzle.  Ideal expansion is to atmospheric pressure at the exit plane; such was not achieved at high altitudes.

Minuteman II had a new larger Stage II engine which used secondary injection for attitude control, where Freon was squirted into the solid propellant nozzle about 1/3 down from the throat, creating a side force.  This program is described in a separate MM II chapter.

 

The photo at right is of analog amplifier integrated circuit used in Freon Dump system.

Thrust vector control was achieved by squirting Freon into the exhaust nozzle, which turned to steam and imparted a side thrust relative to the missiles center of gravity – thus performing attitude control.  A maximum specific impulse of about 130 lbs/lb was achieved.

 

The Autonetics Control unit also included Transistor switches used to command the Warm Gas Roll Valves.

Excess Freon Dump System, I gave paper on this at symposium in Philadelphia.

            We were having problems communicating requirements from Aerojet Propulsion to TRW Propulsion to TRW Guidance & Control to Autonetics and back.  It was discovered that Ron Frazinii of Autonetics and the Aerojet Roll Valve supplier happened to be in a night class together.  They arranged to bring valves and transistor drivers together, work out what was needed, prove it worked, and then sent an interface agreement they worked out back through channels. 

            Kick Back Diodes: The technology at that time did not include power transistors with kick back diodes so it was necessary to build in our won protective diode and resistor.  When a valve has been turned on, a flux field is built up by the coil.  When the transistor is cut off, the coil field collapses and tries to push current through the closed path. Voltage builds up beyond what the transistor can handle, which wipes out the transistor.  By adding the diode, and current limiting resistor the Inductive force shoves current back to the battery, serving like a relief valve.  Mechanical switches on electrical go carts are often zapped because voltage arches through, a protective diode can save the switch.

            Fluidic Logic with Doffle Men  were the product of MIT’s Diamond Ordnance Lab, where they came up with a method of doing “fluidic logic”.   This looked very promising as a means of performing logic following a nuclear event that wiped out electronics.  Corning Glass etched these circuits into logic and it received quite a bit of interest for a while.

            Aerodynamic Bump Control: I had been reading a book on Boundary Layer flow by Schlicting  a German Aeronautics Engineer who wrote of work done during WW II on boundary layer phenomenon. I experimented with the idea of using Dofflemen to cause or eliminate boundary layer flow over an “aerodynamic bump”  The equations in the book were written in European notation where a dot between two numbers was the decimal point and did not mean multiply.  It was an interesting mental exercise but I dropped it, I couldn’t find a suitable application.

I also experimented with the idea of a ‘stepping” servo actuator, base on the above design.  It was based on the thought that you only need three teeth in a gear: to hold, advance or retract. At the time I drew the concept I believed it would work – but did not like it’s vulnerability to contamination.  I didn’t have trouble letting go of the idea.

            When the Minuteman II work slowed I worked on a Nose Control Concept, where attitude control would be done by use of attitude control engines at the front end, where they could be used for all three booster stages.  Paul Stiglic read my paper on the concept & discussed it with Buxton, who arranged for Paul & I to present this to Aerospace.  Paul had previously worked for Aerospace, and presented the idea.  Aerospace was trying to beat out TRW as advisors to the AF. They were selected for some other work but the AF kept TRW as advisors on MM III. The nose control idea was being given very serious consideration by Aerospace, when I was abruptly assigned to a new classified endeavor.

The Nose Control Idea was revived by others after our work on MM III post boost came to an end.  I had previously proven to myself that what looked good at first would not work in practice because the lever arm advantage, obvious when controlling stage I from the nose, was not sufficient for control of stage III.

 

Left: MM II Equipment by Autonetics

MM III Post Boost Control System, began as a secret project where multiple H-Bombs replaced a single A-Bomb on top of a minuteman missile. I was later made supervisor of systems requirements and integration on that program which is described in a separate MM III chapter.

 

Left: Looking forward into the PBPS, axial engine center, fuel and oxidizer tanks on each side. There are 4 pitch, 4 yaw and 4 roll bipropellant attitude control engines mounted on the sides, in flight this area is covered by a “tent”.  Both are at Smithsonian.

Right: looking aft into the Guidance and Control section. Round object is the inertial platform which protrudes into the PBPS section. Three box items are Inertial Platform electronics, guidance computer, and flight control electronics; battery in center..

   

This system is on display in the Smithsonian Museum

   

 

 

MM III model in Smithsonian plus 3 H-Bomb mockup.

 

Silicon Controlled Rectifier Power Supply                 Conventional transistor regulated power supply

As an escape from work tasks I continued to dabble at home in my electronics lab set up.  New devices called Silicon Controlled Rectifiers had come out, as well as devices for controlling them.  Using these I built my own semi conductor variable DC power supply from AC input.  This was to replace my Variac Transformer, to provide various low voltages typical of transistor experimental needs. I built the system as described in the following diagram and it worked very well.  This is in Oberlin Museum

We were not permitted to use SCR’s for Minuteman as if was believed they would be too vulnerable to nuclear effects and trigger when unintended. 

Layoff Time: The very intense Minuteman III Post Boost Control System work eventually came to an end, combine with heavy layoffs, the dreaded phase for every aerospace engineer.  Of 75 on that program 6 of us remained.  Though I had been rewarded with increase in classification and pay during the effort, I found myself out of a job and in search of what could be our next endeavor.  I knew I too would be laid off if new work could not be found. 

            MX (Missile X) During idea brainstorming it was assumed there would eventually be a follow on to the Minuteman series; we had completed I, II & III and referred to a possible next as MX.  The term used by Lou Purpura and I caught on and become the formal R&D name of a new missile system.

New MSI TTL family of logic devices called (medium scale integration) (transistor to transistor logic) had just come out.  I found full page advertisements, from multiple semi-conductor firms for new  TTL chips in dual inline packages. Transistors first come out at the time of MM I, and Elliott Buxton had pushed for the idea of building a Digital Flight Control computer while all other electronics such as Inertial Navigation and Thrust Control Units electronics was Analog transistor electronics; replacing vacuum tubes on the prior Navaho mach 3.5 Intercontinental missile.

During MM II, then MM III semiconductors were integrated into flat pack logic elements, among the first being analog amplifiers and digital Flip Flops.  Flat packs were preferred for military use as they could be soldered in place and better survive severe shock & vibrations loads.  The first TTL devices came in sets of 4 logic items per device.  The dual inline package permitted quick experimental “bread board” layouts by poking through a punched card then “wire wrapped” for connections.  Logic, packaged in sets of four, was a big step at the time, two in series provided 8 bits, where 7  bits needed to define a complete alphanumeric  ASCII  (American Standard Code II), the standard created for telegraph systems and now used for all keyboard communication.  

  

Dual in line packaging swept the commercial market place                               7 bits needed for ASCII alphanumeric code

Harden electronics against nuclear event: When we left off on the MM III Post Boost Propulsion Design there had been concern about the vulnerability of our missiles to Nuclear Events, where a nuclear explosions above our launch sites would destroy our retaliatory counter strike.  If our electronics could not survive the effects of nuclear radiation, the systems would be lost though mechanically still functional.  I knew that digital logic could survive a nuclear effect much better than our analog devices.  With the new TTL devices coming out it should be possible to convert our down stage Nozzle Control Unit electronics from analog to digital. 

Go ahead, see what you do:  I paid a visit to my long time friend Lou Purpura, in his Mahogany Row office, on staff to Chief Engineer Tom Shuler and Program Manager Bob Kazeebee.  I expressed my idea to Lou, who agreed with my reasoning when I said they ought to start someone working on how to digitalize our down stage flight control electronics.  As I started out the door Lou called out, why don’t you see what you can do about that?  I poked my head back in saying, you know I’m a mechanical, I don’t know anything about electronics.  He called back, “since when did that stop you – go ahead and see what you can come up with”.  I found myself  saying OK I’ll look into what might be done.

The initial transistor logic devices were built on the basis of discrete part flip flops as above left and these were interconnected to form counters, shift registers serial adders, etc.

   

CMOS (Complementary Metal Oxide Semiconductor) came out after TTL was already established.  CMOS  is complementary because it’s made of N and P transistors, where a command that turns one on will turn the other off.  A CMOS device is always off except for the instant when it is switching.  CMOS did not heat or leak as did bipolar TTL.  CMOS eventually replace TTL and made the Micro Processor possible, thousands could be packed on a given chip and not overheat.  A transmission gate is where the P and N are operated in parallel, and connected so both are on or off at the same time..

            The TTL transistor has a Collector input, Emitter output and a Base control – current can only flow in one direction. Current through the base enables flow from the collector and out at emitter, a small amount of flow controls a large amount..

            The CMOS has a Source input, Drain output and Gate control.  The term complimentary indicates that if an on signal applied to the Base opens the Source and close the Drain, then the inverse off signal will close the Source and open the drain, they were complementary, each the opposite of the other.  CMOS does not leak current, it is a charge coupled device.  The Motorola term Transmission Gate, indicated that signal current could flow either way.

TTL logic and CMOS logic hot on it’s heals made it simpler to made a broad family of MSI integrated circuits.

 

Rockwell-TRW-Lockheed-Navy meeting:   Lou Purpura called and invited me to be part of a meeting to compare missile control systems concepts.  We had been having such meetings since MM I and found the meetings of mutual benefit.  During this visit we were taken to a Lockheed solid propellant engine test site where they were testing a “Gimbaled Engine Nozzle”. It was a brilliant design, where dog nut washer layers of rubber attached the engine nozzle to the case.  When the case pressurized upon ignition the internal pressure caused the rubber layered segments to behave as a liquid permitting motion of the nozzle.  Form Blocks under a Hydro Press with hard rubber in the head, had long been used to wrap aluminum parts over formed shapes, under pressure rubber flows like a self contained liquid.  This gimbaled nozzle design used the same concept and is now the preferred standard for all solid propellant rocket engines.

No raceway on submarine missiles.  We discovered Lockheed roll requirements were very small, due to the fact they had no protruding raceway to catch side winds at launch.  Upon our return I began work on concepts to use a signal wire data buss between stages.  I made calculations on roll disturbance caused by our raceway and of how we could reduce roll control requirements and via Lou provided the results to TRW advanced planners.

 

Our raceway protruded about 6 inches acting like a fin catching side winds which could cause a launched missile to roll.  The guidance system could not accommodate large roll magnitudes, thus roll had to be controlled.

Data Buss: I began work on a digital data buss to help achieve a “flat raceway”.  I set about making a drawing of missile external wiring – and began work on concepts to use a signal data bus. Rural telephone lines were called “party lines” because multiple families used the same line, each had their own “ring” combination.  I decided to use a serial string of data with a code for the applicable stage.  I worked up a concept of shipping data down and back with address followed by data, were the applicable stage would recognize it’s address, unload commands, and ship back position & status information. I had a concept worked out before I had any idea how to build it.  It was a mistake to call it a “party line” as those who did not grow up in a rural area thought this was a political statement and missed the concept.

Sending for new literature on integrated circuit parts I found a sets of building blocks that should work.  We were moved to building 203 following a people consolidation. Emil Kohler was assigned to help me and after much work I was able to set up an electronics rack with Upstage and Downstage electronics with nothing but data wire between them.

My knowledge of Digital was very limited when I told Lou I’d look into it.  I knew a digital signal only had to be ON vs OFF; so I set about trying to learn something about the world of Digital Logic.  The first MSI TTL devices were sets of four logic elements: AND, OR, Exclusive OR, etc.  I soon learned logic could be performed with either “1” or “0” being the “intelligence” carrier.  Electronically 1 was high (+ 5vdc for TTL) and 0 was low (ground) voltage. 

At this time Boolean Algebra was being taught which was a way of defining input conditions and end up with the desired output conditions with the least number of dedicated logic devices.  The advent of TTL sets of devices and Arithmetic Logic Unit’s that followed negated the need to use Boolean Algebra, useful for hard wired logic. This also applied to Vein Diagrams. A line above a letter indicates a “not”.

While TTL was exploding in the market place, CMOS was being pursued as a pending alternative.  I became fascinated with an RCA CMOS experimental device called the  4016 which was a set of four CMOS “Transmission Gates”, which permitted passing a signal in either direction through the “transmission gate”.  I obtained sample parts and made a servo valve driver out of it.

  

Left 1958 Autonetics (abandon) experimental “Digital Valve”  Mid Moog standard valve, Right Torque motors’

  

Left Mood standard “Flapper Valve” Mid Achelys Ascaini jet valve Right Std Vauum tube servo driver.

            Minuteman servo valves were made by Moog and used a single coil torque motor to drive a flapper.  A main output spool ported high pressure hydraulic fluid to & from the actuator under control.  This control spool was moved by hydraulic pressure on each end.  High pressure went through filter-orifices to each end and dumped back to return though tube nozzles. The flapper, controlled by the torque motor  was placed between these “dump” nozzles.  Under torque motor control one was blocked more than the other moving the spool against centering force springs. This arrangement caused the main control spool to position itself in proportion to the torque motor current. These were called two stage valves, were the flapper part was like a hydraulic pre-amplifier permitting a vacuum tube 8 ma current to control a 3000 psi hydraulic spool. The Minuteman valve design was the same as that originally designed be commanded with vacuum tubes thus readily fit the current switching capability of digital logic elements. 

  

         Single transmission gate       Four transmission gates                       “H” servo valve coil driver

            The new 4016 device included 4 transmission gates which could be connected as an “H” switch set, with the coil in the cross bar and a switch in each leg.  By commanding diagonally opposite sides on and the others off, current could be cause to flow either direction, to command extend, or retract.  When the “switches” were on or off they did not heat.  Recalling work done in the test lab during MM I,  I knew that if a command was changed faster than the device could respond, it would “integrate” (average) the command.  If I cycled a % on or off time fast enough the hydraulics spool could not respond to the electronic dither, the effective signal would average.  I could send a % on time by using a shift register to pass a string of 1’s and 0’s at the same frequency as used to excite the position transducers.  Thus our Analog Servo valve became a Digital Servo valve.  I took the 4016 chip to several respected engineers and told them of my idea of using it as a digital valve driver.  I was politely told it would not work.  So I went to the test lab and in one day set up a test to show the 4016 chip could indeed drive a servo valve – and not heat. It personally satisfying to see the surprised smiles as my friends observe the test.  From then on it was accepted: an Analog servo valves could work as a Digital servo valve.  This had been a hang up for many people for years; convinced these highly reliable valves were not compatible with a digital system.

            RCA had recently come out with a family of CMOS chips, they had been #1 with vacuum tubes and were on track with their venture into CMOS, but they gave up too soon and dropped out.  RCA, GE and Motorola literature was excellent. GE also eventually dropped out.  Motorola continued in competition with new comer Texas Instruments to be prominent players at that time. 

   

         Jim Anderson            Elliott Buxton                    Bob Nease  Lou Purpura   Frank Lettang

            Digital Data Buss and Digital servo Demonstrator.  I placed up stage electronics at the top of an electronics rack and a down stage electronics at the bottom and connected the two with Five wires, plus 5 volts, ground, clock, data out and data in.  I used two 4 bit shift registers to make an 8 bit word, shipping first a stage identification code, then pitch then yaw command to the down stage servo controller, and returned position feedback. 

Joystick activate signal generator: At the top I needed a signal generator to create a pitch and yaw signal. I discovered a dual channel Multi-Vibrator flip flop chip where the output frequency could be set using a variable resistor.  In my shop at home I mounted a variable resistor (potentiometer) referred to as a “pot” on a piece of aluminum angle for pitch, then made another for yaw.  One angle attached to a plate base, the other to the shaft of the pitch pot, and a joy stick tube to the shaft of the yaw pot. It had taken a while to figure out the arrangement and make the parts, but they worked beautifully.  

  

Down stage gimbaled Nozzle: I needed something down stage to drive.  Jim Anderson was able to provide PBPS axial engine gimbal actuators made by Autonetics for us to use in simulating down stage Pitch and Yaw control of a nozzle.  Again using my work shop at home I built a gimbal by use of a large Square Nut to which I attached split pieces of aluminum tubing as In and Out drive shafts.  One end was fixed to a plate and the other tube extended to represent the thrust nozzle under control.  I cut an attachment piece from a block of aluminum to which we could connect the output shaft of the MMIII gimbal actuators.  In the final demonstration design I had two sets of joysticks at the top and two movable nozzles at the bottom to demonstrate handling multiple devices at the same time.

Clock & Timing logic: I needed something to use as a clock for timing the system.  I had worked out a missile message protocol based on a four stage system, were data would be sent it 8 bit segments. I pondered over how to make a clock plus counters and logic to orchestrate this scenario of events.  The only clocks I knew of were those described in Radio hand books that used crystals and associated circuits.  Then I came across a simple clock design in an RCA hand book.  This was really neat and worked just great. 

  

Digital Clock                                                               4 bit Digital 1 of 16 Decoder                            2 bit digital to dual 1 of 4 select 

The clock was set to run a series of counters, which down counted time in binary segments.  These were then connected to decoders, as above, to convert a 4 bit binary into one of 16 time segments. By use of such devices I could create and implement any time segment I needed. 

Holding registers: I needed “latches” or data registers to hold data pending loading or unloading from the shift register “trains of data” arriving at the shipping docks.  I soon found there were a variety of devices to choose from, and the options were growing as suppliers came up with more and more innovative parts. I soon learned that write and read timing was critical.   Timing pulses were square wave.  The initial devices would store data when the “load” signal was high.  These were sometimes called “strobe”.  The output could be read after the data input was cut off., you wrote when the clock was high and read when the clock was low.  “Tri-state” logic came out later where an output was disabled (off line) until enabled and on line.  Initially a common data line was held high by a “pull up” resistor and remained high unless pulled low by a logic device.  When tri-state logic was used the data line floated and there was no inner-connect unless intended.  Later logic was designed that would write or read on a clock change from low to high or high to low.  This permitted faster logic or more functions performed in a given clock cycle.  I found it helpful to separate write and read times by using four sub clock increments per data clock cycle.  This was “hard wired” logic control.  Literature I was reading harped over and over how it was necessary to maintain proper grounding as TTL was sensitive.  I found the devices to be very rugged, even functioning when one pin rested against another; showing only as a slight blip on the oscilloscope, it still did it’s logic function duty.

Digital Summing Junction: I had been trying to figure out some way to compare a command with a feed back to find the error difference.  One day driving to work my speedometer-odometer began acting up, in need of lubrication, and all of a sudden it came to me.  A digital up/down counter is like an odometer that can count up miles or reverse miles – a negative feed back signal to a counter could subtract from a digital command.  I could parallel load a command in a counter, then subtract the feedback from it by down counting to arrive at the magnitude error definable as plus or minus error.  Such a counter is the digital equivalent of an analog  summing junction.  

 

Analog Summing Junction                                                     Digital Up/Down Counter Summing Junction

            Digital Feedback:  Converting the feedback signal to digital was the subject of much study, and the subject of a patent disclosure.  I no longer have a diagram of the method used for this first system.  It used the clock to generate a 5 khz excitation for the position transducer primary and used that signal to command a 4016 transmission gate device connected as a demodulator.  The resultant DC fed into a comparative amplifier, a binary resistance ladder  connected somehow with a phase-locked-loop that determined how long the feedback would down count the summing junction counter.  It’s not worth revisiting just how this was done as it was soon discontinued and no longer used.  This method was replace with a Successive Approximation Register method described in the next section.

After this system was built I demonstrated it to others.  Tom Shuler, our Chief Engineer came and had a look at it.  I showed Tom how you could wiggle the top Joy sticks and watch the “nozzles” below track your motions.  We were all pleased to see Tom’s face change from scowl to smile.  This created considerable interest, in house and with TRW.  I had made a study of Minuteman wiring comparing a hard wired and data bus system.  As usual we provided TRW with the results of my study.

Digital Feedback Patent Disclosure:  At a staff meeting George Anderson our Group leader said there was a request to turn in more patent disclosures.  I was pulled out of my day dream realizing everyone was looking at me.  They were in effect supporting my “playing” with new ideas & I realized I had to submit something.  George said how about turning in that digital transducer idea you had?  I said I never proved it would work and have since dropped the idea.  Frank Lettang said it doesn’t have to be proven to work.  I knew I was stuck so spent a good week writing the idea up and submitting it, thinking that would be the end.  I was called later and told the AF decided to patent the idea and had assigned a lawyer to write up the patent.  The patent lawyer called and wanted more information which I sent to him.  Still later I received his document for review, which I did and returned to him.  Some 5 years later I was called to receive a patent reward check of $1000.  I felt embarrassed because I was not sure the idea would really work, but the patent disclosure write up did read convincingly well.

  

Basis for TRW Data Bus study:  I was asked by Carl Boddy, one of the Autonetics Group leaders, to go with him to a meeting at Norton Air Base where TRW presented the results of their Funded Study of a data bus.  As I listened their assumptions seemed to match mine.  I said to Carl, those numbers sound familiar to me, I wonder where they got them?  Carl said, I know, they are using your report as the criteria for their study, that’s why I invited you to come.  While I was hoping to get study money for us, TRW had proposed the study and funded themselves ! 

I believed I knew how that came about.  I had been at a meeting at Norton Air Base and we had to wait for an AF person to come from LAX to Norton.  While waiting I made a comment to one of the AF officers there saying, “sometimes we do dumb things.”  He picked up on my comment and asked, what do you mean.  I turned to the near by black board and drew a sketch, saying we build an airfoil on the side of our missile that catches side winds at launch and produce a roll torque causing us to have to install roll valves large enough to counter that force.  A few of us already knew that, but he seemed like a fellow eager for a cause to push.  He had taken the bait.  I said a data bus to carry signals would be one way to reduce the cable size.  Unknown to me at the time, not long after TRW was funded. 

 

Night classes from the Chief Engineer of Micro Electronics.  Micro Electronics division of Autonetics was on the same building complex we were, and I signed up for after work hours classes taught by people from that division.  Above is a sketch I made at that time.  The class was tremendously helpful in understanding the rapidly changing technology.

I learned that: semi conductor “chips” are made by photo-etching methods on silicon wafers sawed from silicon “ice cycles” grown by chemical companies.  These were initially grown to a 3” diameter, and are now up to 12” diameter.  The long round raw stock of high quality silicon is sliced into thin wafers.  They are coated with “photo resist”, exposed as for a photo, then developed leaving a pattern of exposed and protected silicon surface.  These are then etched and material deposited and the process repeated until circuits are built up.  Silicon Oxide (rust) serves as an insulator and aluminum wiring is deposited on top for circuit connections.  Many chip circuits are made on one wafer, as if postage stamps on a sheet, then the wafer is cut into chips.  The number of good ones is called “yield” for that batch.  The chips are then mounted on a frame and wire bonded to separate leads.  The process has evolved with time to where some chips are “solder bead” bonded in place all at once.  I had heard of a new process recently implemented called SOAP. With a grimace & smile I was told this was the name given to process and method used to get them out of trouble; the Save Our Ass Process.

TRW at Norton AFB Project office begin plan for new “MX” missile.  Upon completion of my experiment we continued brainstorming sessions on what next.  TRW invited a few of us to sit in on a meeting at Norton AFB where they were looking into building a bigger missile they also called MX, one that could carry many more bombs and need a larger missile diameter.  When we returned Ray Ajamian worked with Jim Jewel, Lou Purpura and I making up a new front end design layout.  I had Ajamian put the G&C system inside the large post boost system cavity, rather than as a separate segment of the missile.  Dale McCoud, our Nav system group leader said, “never, our Inertial Guidance System will never be inside the Post Boost Propulsion package.”  I said, Dale, there is plenty of empty space inside, there is no justification for making it a separate section.  And that is the way it was eventually done, a “G&C drawer” in the side of the post boost propulsion system. 

            Internal Design Review:  About this time we had a design review that included Bob Nease our chief Scientist and other key engineers, where they went over the data bus design I’d come up with.  Right away they wanted to know how I was going to do signal conditioning.  I made the foolish statement that with digital we did not need them.  Mal Johnson said you should give that more thought, he believed there would need to do shaping and filtering of the servo loop signals.  Mal was right, a short time later we learned of the Funded Propulsion contractor study where they intended to power the actuators with solid propellant and use gas turbines for servo power control.

            Servo-Actuator Study Contract to Motor Contractors:   TRW Propulsion had convinced the AF to funded a study by the motor contractors to make nozzle control servos for the new kind of single buried nozzle that could be gimbaled using the rubber layer movable joint method.  The contract stated that the study was not to include hydraulics, as it was already known how to do hydraulics. My data bus design concept had assumed the use of simpler proven hydraulic servos.  I grimaced at the idea of clutching the energy of a 100 hp gas generator power source – through a flex cable no less?.  It became obvious such servos would be far different to control.  Working in the McGee Tire Shop back home I had occasion the use a flex shaft driven heavy duty wire brush.  I had found that ¼ hp motor almost tore that tool right out of my grasp when the wire brush bit in.  I KNEW they would have a terrible time holding bearings on such a shaft driven by 100 hp source.  And they did, the bearing gave way in their tests.

Hydraulic Servo nil filtering – Turbine Gas Servo much filtering

Reorganization and location:  We were moved into bldg 231 where Mal Johnson and I were assigned to share a ground floor office.  We were now on staff to Group Leader George Anderson and as a part of Navigation System.  George’s Group made the components used in the inertial platform, like the analog servo controls and test equipment, with many high quality people working for him.  This made it easy for me to discuss with Mal what we would need for these new kinds of servos.

Using my black board I made the above definition in accordance with Mal’s comments. This became the design criteria for a servo control signal processor.  It was agreed that if the signal processor could perform the above functions, we should be able to accommodate whatever the motor contractors came up with.

            Who would be Responsible for Servo Actuator Electronics?  We had meetings with TRW G&C about what would be needed for servo actuator control electronics.  They were asking what would happen if the electronics was given to the Motor Contractors along with the servo actuators.  This was discussed in some length.  I kept saying the responsibility for control and stability should remain with Autonetics.  That from past experience with roll control on stage II etc we knew motor contractors did not have the expertise to do electronics.  At this point all were locked on the idea of having a data bus with servo electronics down stage.  They wanted Autonetics to be the ones responsible for testing the adequacy of any system – but who would design the electronics for the servo actuators was left up in the air.  The designers of the gas driven servo actuators for motor contractor tests were providing their own electronics. 

Abandon Data Bus – Use Direct Wire:  I made layout studies on the idea of doing away with a data bus and moving all electronics up stage.  I found that this would fit just as well as a flat cable, especially if there was no need to carry battery power as well; it was a doable concept.  I went for another visit with Lou, saying I believe we should work on the proposition that we do all the downstage electronics functions up stage – that way we can be assured of keeping that part of the business, and perhaps we could find a way to time share the electronics from one stage to the next.  It only had to handle two stages at a time for a brief period during staging.  Lou agreed – adding we can probably make it a part of the Flight Control Computer. 

            Even after I’d worked the details on how to do this, selling the idea encountered the momentum built up for a data bus.  What had been sold had to be unsold; I felt I was going upstream while others were going downstream. 

            Digital Arithmetic and Shaping Networks:  It had become obvious that the system concept I had would be required to do data processing – I began to call it a signal processor, or a digital P-92, replacement for our current upstage analog P-92 controls electronics box.  This became a totally new challenge for me, I had to determine how to perform digital computations and needed a model of what such a signal processor should do. 

            Digital Computer Design Book:  On a week end visit to south coast plaza I came upon a book on Digital Computer Design; I bought it and poured myself into learning how to do arithmetic computations.  Thankfully the industry had come out with an Arithmetic Logic Unit chip, and later with a Look Ahead Carry chip.  By use of this book I learned that you need to precondition binary numbers to be either in 1’s Compliment or 2’s Compliment before or after doing an arithmetic operation.  I agonized over which way was best.  I also studied architecture previously used and applied it to the new chips available to me that were not covered by the book.  There were no “cookbook” designs to follow but I was able to extrapolate.  One of the things I found useful was a Booths Algorithm, which was the logic used associated with look ahead for multiplications. 

            Multiplication by repeated addition:  You multiply by performing repeated addition.  The Arithmetic Logic Unit could add or subtract but could not do multiply or divide.  I also found I could do division by shifting decimal point, thus multiplying. However our application did not need to divide, but multiplication demands would become tremendous and become a critical factor in the design. 

 

LaPlace, Z Transforms, and Sample Data  shaping methods

            Sample Data Systems:  I was having a terrible time reading many books, becoming bogged down trying to determine how to perform signal conditioning function with a digital processor.  I was becoming as irritated with the books and I was with my own ineptness.  Dr Blair Bona came to my rescue.  Blair would often come in to visit with Mal and observed me struggling with my face in a text book.  We’d become acquainted on such things as how to rig up switches to turn on/off garage door lights from house and garage.  Blair said forget that stuff in those books this is what you need.  He proceeded to my black board and wrote a lines worth of differential equations, which I could follow.  He then expressed the same information in Laplace transforms used for analog systems, which I didn’t understand but could track to a degree.  He also showed Z Transforms then converted those to Sample Data representation.  I didn’t understand right away how it worked, but I could certainly understand the data processing method.  It was as if someone had written translations on a Rosetta Stone – this immediately illuminated the way to do things.  I said don’t erase anything until I can write that down.  Thank goodness he happened to take an interest in that because it lifted me out of a pit, I had been lost.  Using combinations of information I began the design of a Digital Signal Processor.

Digital Processing required for One Gas Turbine Servo Actuator

            With this Sample Data Loop network diagram I knew what I had to do. 

            Arithmetic Logic Units:  The ALU was a godsend to the computing business.  Prior to it’s arrival arithmetic was done by use of shifting “A” numbers and “B” numbers through a two bit adder and accumulate them in a “C” shift register.  The ALU could handle four bits in parallel.  They were also equipped with four function control inputs that defined what function to perform. 

            Look-ahead Carry:  soon there was a companion Look-ahead carry chip that permitted automation of the carry process.

            Logic Notations:  you will notice the use of letters, some with lines above and some without.  A line above means it’s a NOT function.  The output of flip flops are denoted as Q and Not Q.  Q is used for output in lieu of O so as not to confuse it with Zero.  The Q and Not Q indicate that what ever Q is the Not Q is the inverse.  For example if A = 1 then Not A = 0.  if A =0 then Not A =1.  (symbol look up tables on this word processor do not include Boolean Algebra symbols).

            Fortunate for me, the new ALU’s were creating a big stir and trade magazines were including articles such as above right on how to mechanize multiply operations.  My next task was to set up the necessary parts such as latches, shift registers, memory devices, etc plus logic and timing to make it work.  A big hurdle was choosing and handling the 2’s complement numbers.

            Binary, Hexi-decimal, 2s compliment and 1s compliment Numbers:  Hexidecimal numbers permit dense monitor or printer display of memory content; one Hexidecimal column vs two decimal columns.  1s or 2s compliment numbers are require when performing binary arithmetic.

Most significant binary bits at left, sign bit at far left.

Decimal

Hexi-

decimal

Signed

binary

2’s

complement

1’s

complement

15

F

01111

01111

01111

14

E

01110

01110

01110

13

D

01101

01101

01101

12

C

01100

01100

01100

11

B

01011

01011

01011

10

A

01010

01010

01010

9

9

01001

01001

01001

8

8

01000

01000

01000

7

7

00111

00111

00111

6

6

00110

00110

00110

5

5

00101

00101

00101

4

4

00100

00100

00100

3

3

00011

00011

00011

2

2

00010

00010

00010

1

1

00001

00001

00001

0

0

00000

00000

00000

 

 

 

 

11111

 

 

 

 

 

-1

-1

10001

11111

11110

-2

-2

10010

11110

11101

-3

-3

10011

11101

11100

-4

-4

10100

11100

11011

-5

-5

10101

11011

11010

-6

-6

10110

11010

11001

-7

-7

10111

11001

11000

-8

-8

11000

11000

10111

-9

-9

11001

10111

10110

-10

-A

11010

10110

10101

-11

-B

11011

10101

10100

-12

-C

11100

10100

10011

-13

-D

11101

10011

10010

-14

-E

11110

10010

10001

-15

-F

11111

10001

10000

 

            Electronic Calculators:  Came out about this time and Autonetics Micro-Electronics Division began producing calculator chips which they were selling to the Japanese, who were then selling them as part of calculators and as chips back into the US as if made in Japan. 

            I was set up in a flight control electronics test lab and the lead man, had recently worked for the Micro-Electronics division and had some experimental items in the lab.  Our lab did not have digital test equipment, so I improvised by using calculator parts as keyboard and display, under which we built memory registers etc to serve as a signal generator and response reader.  Without this we would have been lost.  We had a dual trace scope which helped test wiring but we needed the equivalent of a computer to issue and read a command scenario.

            This piece of “Test Equipment” is in the Oberlin KS museum.

            I found the above unit for sale at Sears Buena Park, for $60.  I bought it and from then on the slide rule sat unused in my desk drawer.

 

            I was in the habit of carrying this “pocket” slide rule in my shirt pocket along with badge and small address/phone number book, plus 6”steel ruler, with conversion table imprinted. .

\

Layout of Arithmetic Logic Units set up to perform 8 bit computations for servo loop closure using Sample Data mechanization..

            It took some time before I could figure out how to do this for a single multiply process, and much more time to handle a full set of servos and their shaping networks.  I had this arithmetic, poor mans micro-processor unit, working before I’d worked out how to handle the feed back.

            A micro electronics engineer told me he was working on a Successive Approximation Register and explained roughly how it worked.  A short time later I found such a device, with an appropriate application circuit in an AMD sales booklet.  I ordered one and built it into our system.  Yes this is the same AMD now giving Intel a rough time in the CPU market for PC’s.  The SAR compares it’s guess with the unknown signal to home in on the unknown.  On a scale from 0 to 100 it will first guess 50, then if the unknown is lower, next guess 25 and so forth until it has resolved it’s lowest bit.  It was very fast and I was delighted to incorporate it into our system.  .

   

SAR device with associated circuitry                                           Later low cost hand calculator made in Mexico