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-request@febo.com wrote:

--
Bill Ezell

They said 'Windows or better'
so I used Linux.

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 wje@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-request@febo.com wrote:

-- 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.

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 robert8rpi@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 wje@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-request@febo.com wrote:

-- 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.