This is a circuit for a military gyro* that I'm trying to understand. Power input is 28vDC at A & B on the upper left. Output is 3-phase 400Hz AC (28v, I believe) on G, H & K at the bottom. VR1 is a 12v Zener. The emitters of Q6, 7 & 8 are tied to the collector of Q2, which thru a fast diode goes to input ground. Chassis ground is separate from everything, and the circuit ground has no direct connection to anything tied to input ground. Connection N on the bottom, tied to the collector of Q2, is open.
I've figured out that L1 & L2 and associated capacitors are for noise suppression. What is the source of the ground in the main circuit and the power supply (lead 3) of the opamps? What is the purpose of C1 capacitor on the left off of the main circuit board, and does it have any role in establishing the power rails for the main circuit?
(B1 is a warning flag motor & can be ignored; VR2-5 are protection diodes for the lamp circuit, and again irrelevant to the question)
Any thoughts on what's going on here would be greatly appreciated.
Thank you all.
*-BTW I'm trying to fix this thing, and if anyone knows of a source for the U2T101 and U2T151 darlingtons, well that would get you even more positive mojos!
I've figured out that L1 & L2 and associated capacitors are for noise suppression. What is the source of the ground in the main circuit and the power supply (lead 3) of the opamps? What is the purpose of C1 capacitor on the left off of the main circuit board, and does it have any role in establishing the power rails for the main circuit?
(B1 is a warning flag motor & can be ignored; VR2-5 are protection diodes for the lamp circuit, and again irrelevant to the question)
Any thoughts on what's going on here would be greatly appreciated.
Thank you all.
*-BTW I'm trying to fix this thing, and if anyone knows of a source for the U2T101 and U2T151 darlingtons, well that would get you even more positive mojos!