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I'm no crystal-gazer, said the crystal ball
I slightly soldered one of my fingers tonight in the pursuit of history, but the gyro flux gate compass is going to work. More accurately, it still works, it's just in pieces on the work bench of my father's laboratory and the amplifier will need substituting since even if we trusted its vacuum tubes not to blow out and fry everything else, it doesn't come from quite the same system as the other parts and we're not actually sure if it would work with them. The compass itself is composed of a gyro-stabilized transmitter which is placed out in the wing or the tail of the plane so as to receive as little magnetic interference as possible from the contents of the interior while it interacts with the magnetic meridian, an amplifier which band-pass filters the 400 Hz of alternating current it gets from the plane into the excitation voltages necessary to drive the other two parts of the compass as well as efficiently circulating the unequally induced voltages which serve as the transmitter's direction signals onward, and a master indicator which the navigator reads like a regular compass dial once it has translated the amplified direction signals through its cam mechanism into the placement of its pointer, with the auxiliary option of repeat indicators to be distributed throughout the rest of the plane as needed. We have two transmitters of slightly different vintages, so we checked both of them with an ohmmeter and then with an LCR meter in order to make sure that all the contacts and coils and wires were still resisting and reacting as intended after eight decades and then we hooked each in turn up to a signal generator since we don't have a B-17 and plugged it into an oscilloscope and beheld the asymmetrically green sine wave of the three coils of the flux gate mistaking my rotating a strong magnet near them for cardinal movement through the magnetic field of the earth; it also responded to spatial manipulation, i.e. me turning it back and forth in my hands in a room full of computer equipment. We may have overdriven the transmitters slightly since we were supplying their voltage peak-to-peak rather than root-mean-square. We did have to resort to the manual from 1945 in order to be sure of the survival of the master indicator since the wiring diagram was unexpectedly unhelpful as we tried to check out the magnesyn or the motor, but mostly what it turned out to need was some contact cleaner from my father. We have no repeat indicators to worry about and as mentioned previously the amplifier is attractive but irrelevant. The connectors and cables may or may not be a pain. The point is that I am delighted that this piece of one hundred percent analog instrumentation almost certainly older than my mother works. We could tell the gyro was still functional because it rolls like a magic eight-ball under the transmitter's round plate of a window, but it was much less clear until tonight if the ghost was still in the machine and there it was like some kind of slewing heartbeat on the screen. My soldering skills remain rudimentary, but three of the four wires employed in testing the transmitters were my handiwork and demonstrably did their job and I am taking even small achievements right now. Should we succeed in reconstructing the compass completely, I will be pretty thrilled.
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It makes me so happy. It's made out of magnetism and gears with some wires and glass in between and it is incredibly accurate and, electrically speaking, compact. And durable! There is no practical application in restoring it, but I love that it's possible without too much replacement.
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(My soldering always looks like the murder scene of some sort of silver-blooded fey.)
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tl:dr never stop being you please don't go to Charn though
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The mid-20C pre-chip tech is so beautiful and durable, the absolute pinnacle of design, engineering, and craftsmanship. (Is it waterproof? Could you take it out on a boat for a fun run to watch it work?)
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Though please try not to solder your fingers together, it'll make the typing awkward.
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The point is that I am delighted that this piece of one hundred percent analog instrumentation almost certainly older than my mother works. --I understood that, though, and think it's wonderful.
(Question: which starship would you like to be assigned to?)
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I must confess that when I encountered the gyro flux gate compass my brain went to “Sovay’s new steampunk universe” and I’m delighted that you were able to fix it and make it fly!
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Thank you! I love that it works, both as originally designed and in the present day.
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Thank you! It's such a clever design. The voltage of the direction signal itself drives the motor which moves the pointer to the correct heading on the indicator dial! It feels very physical.
(My soldering always looks like the murder scene of some sort of silver-blooded fey.)
That's a wonderful image. It makes me think of a scene that always stuck with me from Robert Newman's Merlin's Mistake (1970) involving an invisible serpent with mercury for blood.
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*hugs*
I'm not going to Charn. Besides, I have a compass.
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Walter Shawlee, the Sovereign of Slide Rules. “In 50 years, the computer you are using to view this webpage will be landfill,” he wrote, “but your trusty slide rule will just be nicely broken in!” His mother, by the way, played Sweet Sue in Some Like It Hot.
Nine
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Thank you! At the moment it is more like a restoration in waiting, but I am indeed emotionally attached.
The mid-20C pre-chip tech is so beautiful and durable, the absolute pinnacle of design, engineering, and craftsmanship.
It has increased my already substantial bitterness about planned obsolescence, I can tell you. Nothing special was done to preserve this compass. Its components were in use well beyond WWII and they weren't kept in a museum once they were taken out of their last plane; my father found them at an MIT Swapfest in 2015. The amplifier shows signs of previous repair along with its other issues. And all the transmitters needed was 2.5 volts of alternating current at 487.5 cycles per second and they lit right up.
(Is it waterproof? Could you take it out on a boat for a fun run to watch it work?)
I would assume the answer is yes since the Bendix Corporation provided the exact same model of compass to the Navy, but we are more likely to tool around with it in a car and see what happens!
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Thank you!
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Thank you!
Though please try not to solder your fingers together, it'll make the typing awkward.
It was not that much solder, luckily. I was soldering a kind of adapter onto the end of the wire which I had pinned down with a pair of wire-strippers and the wire-strippers rolled off and the wire sprang up and the solder spattered onto my fingertips and I dropped the iron, which fortunately swung off the edge of the table on its cord and did not contact anything flammable, like other parts of me. It didn't even blister, it just hurt in the moment. I hadn't soldered anything in at least twenty-five years.
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Thank you! I fear it would not yet be safe for me to request assignment to the starship I build myself.
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Do you have a favorite piece of analog tech you have repaired?
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Thank you! I can do nothing about the fact that the transmitter looks like a flying saucer but be charmed by it.
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It's true. The oscilloscope helps.
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Thank you!
Synchronistically, I came here from this obit forWalter Shawlee, the Sovereign of Slide Rules. “In 50 years, the computer you are using to view this webpage will be landfill,” he wrote, “but your trusty slide rule will just be nicely broken in!”
I had no idea there had been a slide rule revival! The one in my possession is inherited and some decades older than I am.
His mother, by the way, played Sweet Sue in Some Like It Hot.
A legend!
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The analog future.
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Thank you! It cannot quite fly yet, but it's waiting.