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1. Tube🌞Time (tubetime@mastodon.social)'s status on Friday, 15-Sep-2023 21:38:32 JST Tube🌞Time

   this is an aircraft avionics mystery! it's made by Bendix, but i have no part number because the cover is missing (bought it this way from our local electronics flea market). as this video shows, i got it to work, and this thread explains how...

   • Tube🌞Time (tubetime@mastodon.social)'s status on Friday, 15-Sep-2023 21:38:28 JST Tube🌞Time

     in reply to

     in fact, the magnetic amplifiers it uses are exactly the same. Ken wrote a very nice article about magnetic amplifiers for the IEEE Spectrum, so i won't explain it again: https://spectrum.ieee.org/the-vacuum-tubes-forgotten-rival

     Freax likes this.
   • Tube🌞Time (tubetime@mastodon.social)'s status on Friday, 15-Sep-2023 21:38:29 JST Tube🌞Time

     in reply to

     this is step 2 after i tidied things up a lot.

   • Tube🌞Time (tubetime@mastodon.social)'s status on Friday, 15-Sep-2023 21:38:29 JST Tube🌞Time

     in reply to

     • Ken Shirriff

     i compared notes with @kenshirriff who has been reverse engineering a Bendix Air Data Computer: https://oldbytes.space/@kenshirriff/110578423219847109

   • Tube🌞Time (tubetime@mastodon.social)'s status on Friday, 15-Sep-2023 21:38:29 JST Tube🌞Time

     in reply to

     many of the components are identical between the two units, which is why i think mine is also made by Bendix.

   • Tube🌞Time (tubetime@mastodon.social)'s status on Friday, 15-Sep-2023 21:38:30 JST Tube🌞Time

     in reply to

     the electronics module has a number of transistors, resistors, capacitors, and other components.

   • Tube🌞Time (tubetime@mastodon.social)'s status on Friday, 15-Sep-2023 21:38:30 JST Tube🌞Time

     in reply to

     the electronics module is connected to the rest of the unit with a 15-pin D-sub connector, so it comes apart easily. on the other side, you can see a transformer on the far left, and next to it are two magnetic amplifiers!

   • Tube🌞Time (tubetime@mastodon.social)'s status on Friday, 15-Sep-2023 21:38:30 JST Tube🌞Time

     in reply to

     i spend a few hours puzzling over the electronics module and reverse engineered a schematic. this is step 1, which matches closely with the physical layout.

   • Tube🌞Time (tubetime@mastodon.social)'s status on Friday, 15-Sep-2023 21:38:31 JST Tube🌞Time

     in reply to

     closeup of the Digital Analog Converter. based on the patent numbers, it appears to use a system of brushes to convert the shaft position to a set of parallel bits.

   • Tube🌞Time (tubetime@mastodon.social)'s status on Friday, 15-Sep-2023 21:38:31 JST Tube🌞Time

     in reply to

     on the other side of the unit you can see two more synchros as well as a "motor and rate generator" which is basically just a motor with an extra winding that generates a voltage proportional to the motor speed.

   • Tube🌞Time (tubetime@mastodon.social)'s status on Friday, 15-Sep-2023 21:38:32 JST Tube🌞Time

     in reply to

     there are 3 26-pin connectors. there are four synchros inside, a motor, a "digital analog converter", and two large potentiometers. there's also a gear train and an electronics module on top.