Selsyn feedback


Thread Starter


I am reworking an DC conveyor that is using selsyn to do synchronization. The selsyn gives me a position error signal (0 to 90V AC proportional to the difference in position between the signal selsyn-master- and the differential selsyn-slave-) It is pretty old technology but it is installed and has been running for years so my customer does not want to change it. I need to use that error signal to regulate my drive speed (trim). My drive analog input use +/-10 VDC signal. How can I convert that 0-90VAc to +/-10 VDC. I know AB use to make a "Reflex demodulator" (12M03-00103-01) but it seems that they do not offer it anymore. Any idea?

Curt Wuollet

How about an active rectifier, an op amp with the diodes in the feedback path so that it approaches an ideal rectifier. Then divide by three and
offset around your operating point. Does selsyn reverse phase on the other side of zero? I think it does, so you would want to invert your signal when the phase reverses. Not very difficult at all.


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Electro Mechanical Systems

For the 12M03-00103 Reflex Demodulator, check with

Gemini Corp. of Wisconsin
PO Box 380
W61 N14280 Taunton Ave
Cedarburg,WI 53012
Phone 262-377-8585
Email: [email protected]

I am not familiar with the function of this board but I know that Gemini is building and selling them.

Mike Adkins
Electro Mechanical Systems, Inc.