Sensor Design

[bengaltiger14]

I am trying to come up with a design that would track the position of a wire. The wire will have a permanent magnet attached to its tip. I will use a electromagnet to move the wire in only 1 dimension.

Here is what I was thinking.... I would put a stationary aluminum plate some distance from the electromagnet. The wire with the permanent magnet will be placed in the middle. The wire will be moved according to capacitance. What kind of circuitry would be need to "measure" the value of capacitance? The capacitance value will tell me the position of the wire.

[Bob S]

People have used "capacitive" electrodes to very accurately measure the transverse position of a taut wire carrying a RF frequency electrical current. The accuracy is ~0.1% of the aperture between pickup electrodes, or better. Is there any way you could put a current in the wire?

Bob S

[Mike_In_Plano]

You might try this circuit. It's very common and fairly easy to use in the sub pF range.

Mike