Andy:
Maybe you could make up some type of mechanism for your application through the use of the mini-latching solenoid pictured here. It has an integral spring that holds the plunger in the extended position but will stay pulled in if manually pressed. It is possible to unlatch the magnetic catch by applying an electrical pulse to the coil in the proper polarity. It would be interesting to experiment and see if it is possible to detect if the plunger is pulled in or extended through some simple detection of what happens in terms of the coil response to a low level signal. Use of the device may be as simple as mounting it in a panel that is at right angles to the operator surface and exposing the end of the plunger through a small diameter round hole. The product is about $2.50 USD each in OEM quantities.



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Michael Karas