Bourns Inc. Puts its Best Foot Forward…every step of the way

In celebration of the 50th Anniversary of the Apollo 11 mission, we are posting this article originally written by our founder, Marlan Bourns in 1969 following the completion of the mission.


“Their spacesuits were really balloons inflated with oxygen.”

– Associated Press

Apollo 11 astronauts Neil Armstrong and Buzz Aldrin carried their own earth atmosphere when they stepped on the moon. And it was Bourns’ job to make sure they kept it.

Three Bourns pressure transducers in the helmet and backpack continuously monitored the oxygen supply of each of the astronauts, transmitting information to gauges worn on their wrists and – via telemetry – to observers on earth.

When the astronauts climbed back aboard Eagle, they discarded their backpacks; thus equipment made by the Instrument Division on Magnolia Avenue in Riverside remains on the moon as one of the mementos of man’s first visit.

The transducers were supplied to Hamilton-Standard, prime contractor for Apollo 11 ‘s portable life support systems.


“Tranquillity base here; the Eagle has landed.”

– Neil Armstrong

Real nail-biters in the epic adventure of Apollo 11 were Eagle’s descent to and ascent from the surface of the moon. And here again the Magnolia Avenue group made a significant contribution with the Model 2203 position transducer, one of the vital instruments controlling the thrust of the vehicle during the critical maneuvers of landing and leaving.

Transducers, however, are but one part of the Bourns-Apollo 11 story, a story that slowly pieced itself together after the flight.

Recognition came sporadically. A notice on the bulletin board in Ames, a congratulatory memo from Guy Entrekin to employees of the Instrument Division, a handshake in Precision Controls, a round of congratulations in Romoland. Slowly the magnitude of the contribution unfolded.


“We’d like to give special thanks to all those Americans who built the spacecraft, who constructed, designed it and tested them and put their heart and abilities into these craft.”

– Neil Armstrong

From lift-off to touch-down, a broad range of Bourns products functioned with the precision asked of them.

Potentiometer 3560S-471-502, a docking position indicator, provided the information Eagle had approached Columbia closely enough to be latched into docked position. It was furnished to North
American Rockwell, Downey, by Precision Controls Operations.

Magnetic Operations in Romoland supplied the Model 3960 DC-DC converter power supply used in the oxygen supply, air-lock and re-entry systems.

From Electronic Components Operations came the 224L-500 adjustment potentiometer used in Apollo’s main antenna, built by Dalmo Victor. The Eaqle’s _ ascent _ fuel control, a product of North American Rockwell, utilized the 3250-500 high reliability square potentiometer.

Arma Division of American Bosch Arma Corporation used several Bourns units in three assemblies it produced for Eagle.

The Signal Conditioning-Electronics Assembly employed the extremely tiny relays, Models 3100 and 3101, as well as the 3280 microminiature adjustment potentiometer. The Caution and Warning Electronics Assembly also utilized the 3100 and 3280. And the Control Assemblies – concerned with the generation, logic control, processing and switching of critical command signals in the guidance, attitude, stabilization, ascent and descent engine – employed high performance 3101 ‘s and 3280’s.

Electronic Components also provided Model 224 high temperature adjustment potentiometers for ground support equipment built by A. C. Electronics and Univac, as well as Model 3260 squares for A. C. Electronics. Other 224’s were used in Boeing’s Saturn 5 launch vehicle, and the 3250 was used in McDonnell Douglas’ Saturn IV booster.

Additionally, ECO supplied the 3250W-888-RC employed by McDonnell Douglas for acquisition of telemetry data, and the 3282 cermet microminiature square used by Milliken in a camera (film) system.


“Beautiful, beautiful, beautiful, a magnificent desolation.”

– Buzz Aldrin

Those fabulous television pictures from the moon that held the earth spellbound the evening of Sunday, July 20, were taken by a tiny television camera developed by Westinghouse Aerospace, Baltimore. Here the Ames, Iowa, plant enters the picture with a 3301 carbon element TRIMPOT®, the smallest potentiometer produced at Ames and ideally suited to this miniature, lightweight TV camera application, as Stan Kukawka noted in a bulletin board memo. Incidentally the 3301 weighs but .02 of an ounce and uses the unique RESISTON® element.

Also used in the Westinghouse television system were ECO’s Models 3001 and 3005 miniature wirewound TRIMPOT potentiometers.

Over on Kansas Avenue in Riverside, Bourns Technical Materials personnel also were happy with the pictures from the moon. They had supplied the standard 4200 series microresistors to Minolta Corporation for cameras used in the Apollo flight. These components are among the world’s smallest discrete cermet resistors.


“A 6.5-pound miniaturized marvel of solid-state electronics, a package of two transmitters and three receivers crammed into less space than in a cigar box.”

– New York Times


Model 4220 inductors from Magnetic Operations in Romoland were used in the radio transceivers with which the astronauts carried on their conversation with an admiring President. And the Model 4210 microtransformer was used in the astronauts’ space helmets for sound amplification.

Model 4210 (a 1/4-inch cube) found further use in the Eagle control system and in filter amplifiers and the inertial guidance system. And a tiny Model 4200 microresistor from Technical Materials was used in a light-sensing meter to measure brillance of stars as the spacecraft threaded its way through space back to earth and home.

At approximately 9:50 a.m. (PDT) Thursday, July 24, the following message boomed over the Bourns public address system in Riverside:



As never before in the history of ex­ploration the journey of Apollo 11 and its intrepid astronauts was a marvel of well-coordinated teamwork.

Extending down from NASA, to the prime contractors, to the subcontractors to the suppliers of the most prosaic com­ponents, everything possible was done to assure the success of the mission and the safety of the astronauts – Neil Armstrong, Edwin Aldrin and Michael Collins. Their safe return is witness enough to the spirit of all who participated.


My thanks and congratulations for jobs well done in the design and production of components that helped assure success of the Apollo 11 mission. As you have seen, the scope of our involvement was across a broad range involving many contractors, who showed their faith in you by specifying Bourns.


Marlan E. Bourns


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