400Hz power supply

[djrm]

Here is a sine wave power generator using a XR-2206 feeding a push pull amplifier with multiple power transistors. There are two large transformers inside, one for the +- 50 volt power supply and another as output transformer. voltage control is by variac on the output series/parallel connected by the switch.

I'm using it to supply some vintage aviation instruments and gyros, experimenting to see how they work.
I can't find any information on the supply but it is working ok for now. 

I would like to be able to synchronise the supply to another I have - I have seen a circuit idea driving the fsk input of the 2206 chip for this purpose, i'll give it a try.

Kind regards, David.

   

[peter scott]

Something in the region of 40 to 50 years ago I made myself a 400Hz supply so that I could run a gyro compass in my car. It worked quite well if I remember correctly. I can't remember what I did for the supply. I think I made a three stage phase shift oscillator followed by a little amplification.

   

Peter

[djrm]

I have done something similar myself, Peter. This supply uses a repurposed motor ESC to drive a three phase step-up transformer to drive the gyro motor. I have added a frequency reference output which I shall use to synchronise the other power supply. I have found out that one supply does not have high enough drive capacity for a larger three phase gyro motor and associated indicators.

   

[peter scott]

Probably true in my case too. I thought I'd try to make mine run again only to find that one of my output transistors (2N3772) has gone EC short. I've ordered a replacement just out of curiousity.

Peter

[Ed_Dinning]

Hi Davis, have you been to Teeside airport; I believe they scrap old passenger jets there, so it may be a source of aircraft instruments for which there is no paper trail

Ed

[djrm]

Here is a photo of my latest acquisition an Azimuth gyro.
   

I intend to incorporate it into this compass and display setup:
   

The gyro mounting frame was quite bent when I received it but everything seems to be working ok. I haven't needed to strip it down. it is supposed to be filled with hydrogen, maybe still has some in it from 1968...
The big power unit is only single phase and it can just drive the motor through a phase shift network but the motor startup current together with the other devices is too much and the fuse blows. 

I can use the three phase supply but need it to synchronise with the other instruments.
D

[peter scott]

Something in the region of 40 to 50 years ago I made myself a 400Hz supply so that I could run a gyro compass in my car. It worked quite well if I remember correctly. I can't remember what I did for the supply. I think I made a three stage phase shift oscillator followed by a little amplification.



Peter

After replacing a shorted 2N3772 my little three phase supply is back in business. The compass takes quite a long time to get up to speed. I guess the decades of idleness will not have helped that.

https://youtu.be/8ePK-Y0OXSQ

Peter.

[djrm]

Here is a photo of the two 400Hz power supplies I've been repairing recently. The first had a leaked, but now quite dry, electrolytic capacitor and an open circuit mains switch.  The other had a missing fuse and short circuit bridge rectifier together with a load of missing nuts and bolts where the PO had attempted something. That one has a wide frequency range from 45Hz to 10kHz with digital selection via rotary switch. I found an aviation frequency meter on ebay this week, now I have just the thing to test it with, unfortunately the calibration on the power supply is way off giving an output of 365 Hz when set to 400 and my frequency meter shows crazy values unless the voltage is heavily filtered before measurement although the waveform looks clean.

Both units are extremely heavy, the big one I had to carry upstairs one step at a time to get it into my office. I was surprised to see it had a 'swinging' choke input smoothing system - seems this is the way to go for a good power factor and less stress on the other components. learned something new there.

I've not been able to find any technical information on either unfortunately apart from a sales leaflet for the top one. Any information would be gratefully received, thanks. David.