Hello mark.

10 Jul 04 21:22, you wrote to Herman Trivilino:

 ml> i remember two three pole devices such that when you moved one the
 ml> other followed but it took three poles to do it... dunno how that'd
 ml> be handled electronically if it'd be done that way at all...

self-synchronous servos, AKA selsyns.

 there's a three-pole stator with a two pole rotor. (so, 5 wires)  the
devices are connected in parallel and the rotors also fed with AC.

the ganetic fileds causes in the stators cause the slave to allign with the
master,  (actually the two units are interchangable)

to read one electronically you'd need to read the the stator voltages and
compare their amplitude at peak.

actually two windings could be used instead of three but that'd mean 4
poles... would be needed (and still atleast 3 wires ...

Possibly a resistor array could be used to extract two 90-degree separated
signals that could be fed to a 2-channel DAC like a soundcard.

Jasen

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