selsyns, synchos ... the airdales just had to be different.....then I guess they were selsyns, not synchos.
The diagram by nsaspook pretty much sums it up. In this case I want to use a SS motor controller.
So, any ideas on a circuit that will do it with a FET instead of a triode, and with no transformers? I think mine is close, but I'm not good enough at circuits to solve for the values or to come up with the correct voltage reducer for the "???" location in my schematic.
You almost have to use transformers to isolate the error signal from the synchro to keep your common-mode noise reduction.
see Synchro-to-Digital Conversion:
http://www.evaluationengineering.co...-synchros-resolvers-and-data-acquisition.html
An example of synchronous phase demodulation with a LVDT signal conditioner chip.
http://www.analog.com/static/imported-files/data_sheets/AD698.pdf
http://www.analog.com/library/analogdialogue/archives/42-08/lvdt.html