Sorry to reply to my own post, but while looking for the mosfet kit I notice that Velleman do a low cost (15 UK pounds, Maplin L85BH ) bipolar 200W (70W RMS) amplifier kit that includes the power supply rectifier and filter. Kit No VM100. http://www.vellemanusa.com/products/view/?id=522101 I've not tried it and am not endorsing it but it looks a good low cost starting point. Robert G8RPI.
________________________________ From: Robert Atkinson <robert8...@yahoo.co.uk> To: Discussion of precise time and frequency measurement <time-nuts@febo.com> Sent: Thursday, 28 March 2013, 12:20 Subject: Re: [time-nuts] OT - DC-10 gyros Hi Bill, The amp I used was similar to this circuit http://www.circuitstoday.com/100w-mosfet-power-amplifier which is a common design. Supply is 45V (unregulated rectified and filtered 30V transformer) so will drive 26V out OK. I've also used modules from ILP in the past, sometimes with a step-up transformer. To be honest even a square wave chopped up 35V DC would probably work OK for these little rate gyros, but they are quieter on a sinewave. Robert G8RPI. ________________________________ From: Bill Ezell <w...@quackers.net> To: time-nuts@febo.com Sent: Thursday, 28 March 2013, 11:18 Subject: Re: [time-nuts] OT - DC-10 gyros It's almost certainly part of the flight stability / autopilot system, as suggested privately by another time-nut. The gyros spin up nicely and run quietly, so sounds like the bearings are fine. I was using an old Yamaha amplifier I had around for the 400Hz drive. I think I'm going to go the audio amp route. The biggest problem I'm having with replacing it is that I haven't found a small amp yet that has enough output voltage. I'm going to breadboard up something tonight - simple phase-shift oscillator driving a pair of FETs in class B configuration with a low-pass filter to clean things up. It actually doesn't have to be all that clean. The gyros are electromechanical devices after all, they're just little split-phase AC motors. As for what I'm going to do with it, why, the same thing we do with our time and frequency related projects - play with it. :) My goal is to get the electronics package fully functional. Fortunately, everything is analog using transistors you can actually see and quad 741 op-amps in real dip packages, and even better, only double-sided pc boards. On 03/27/2013 11:16 PM, time-nuts-requ...@febo.com wrote: > Is this part of an HSI (horizontal situation indicator), ADI (attitude > director indicator), INS (inertial navigation system), or autopilot? Are > the bearings dust? > > Sounds like fun to play with though. What do you plan to do with it? -- Bill Ezell ---- They said 'Windows or better' so I used Linux. _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
