A TAPE RECORDER AND BORED TECHNICIANS


It will be no surprise to anyone that night workers in the Instrument lab sometimes became bored. Monitoring the drift test of SINS gyro is not like doing aerobic exercises; its more like trying to outrun a sloth. The technician assigned to monitor a drift test was required to periodically measure the magnitude of the current flowing through the torquer coils of the test gyro. As part of the ritual performed during the startup of a drift test, this current was caused to flow thru the test gyro’s torquer coils such that the gyro was observed to be stationary with respect to the room. The technician was trying to determine the torque that would be necessary to keep the gyro precession rate as close as possible to the rate at which the room was turning. The accumulated angular difference that resulted from the inevitable small difference in the two rates was recorded using a Bristol strip chart recorder.  It was important that the torquer current magnitude be measured periodically to provide proof it did not vary during the drift test. The current magnitude was measured using equipment that today would be considered as museum pieces. They consisted of a large potentiometer, a galvanometer, a bridge circuit using high precision resistors, and a dust cloth. The dust cloth was necessary to enable the technician to keep the shiny black surfaces of the galvanometer clean. (Dr. Pickrell, the Vice President and General Manager of the Marine System Division, had a habit of writing his initials in the dust and there was hell to pay if they were still there the next time he came by.) The measured value was was entered into a logbook. This left plenty of time for other “projects”.

I had just transferred into the lab from the machine shop. I remember one night being asked if I knew about the tape recorder test. I indicated that I did not. I was taken to an old reel to reel tape recorder that had a set of ancient earphones attached and a microphone. I put on the earphones as I was asked to do. I was handed something to read out loud and the tape recorder was started. I started to read out loud using the microphone and almost instantly found I could not continue. I tried several more times with the same result. During the ensuing discussion with the onlookers, I was informed that they had found nobody who was able to read out loud. I examined the setup and discovered, with the help of the onlookers, that the tape recorder was rigged so that a small time delay was introduced between the microphone input and the output to the earphones. I have never been informed of the reason for this apparent disabling of the brain circuits by this time delay. I still wonder what happened to my brain.

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