[Milsurplus] powering selsyns

[J. Forster]

There are also quite a few commercial versions around. I got a nice NOS
Abbott one from Steve Hiltz about a year ago, but I think he has sold out.

Peter, your're right that a static inverter is the way to go. Were the
ones you built square wave, modified square wave, or sine wave?

Best,

-John

==============


>     There are app notes out there from several chip manufacturers which
> have simple and inexpensive 400 Hz inverters.  I built one which ran
> from 24 volts and drives a 12-120 filament transformer and have used
> it for tons of servo projects.  The parts cost less than minimum order
> size from Digikey and worked at first try.  I even built a 26 volt 3
> phase unit from an app note for little rate gyros.  That one had to
> run from a +- 40 volt supply I salvaged from a stereo a neighbor threw
> out.
>
>
> Nov 4, 2010 01:38:58 PM, jfor at quik.com wrote:
> You can run a 400 Hz Synchro or Selsyn (or motors or transformer) from 60
> Hz, but at reduced voltage  = 60/400  0r 15% of it's rated 400 Hz voltage
> indefinitely. You just won't get much torque or output voltage.
>
> If it uses a phasing capacitor, the value should be increased by a factor
> of 400/60 or roughly 6.6 times.
>
> Motors will run about 60/400 times as fast....  a concern if they are
> driving fans.
>
> Best,
>
> -John
>
> =============
>
>
>> It seemed to be pretty common  with hams in the 50's to stick an ac
>> capacitor is series with the selsyn motor windings and run it off
>> 110VAC. Calculate the reactance required to limit the current to arrive
>> at the value. It worked intermittently at 60 Hz. with no problem.
>>
>> Ralph
>> VE3BBM
> \
>
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