Hey Dave,

I'm trying to recreate your circuit design. I had a few questions though. In the circuit diagram you present in your 3rd post, what is the purpose of the pair of 4.7M resistors, and the 100K resistor, and the TP1 input? What does TP1 stand for?

Also, instead of winding the coils around your rectangular configurations, I am trying to use a solenoid exciter coil, and a spiral receiver coil. Problem is, I am not sure how to interpret the 'optimal' Q values for each part: transmitter and receiver. You use approximate values of 40, and 5, respectively. Could you give me some pointers on how I should approximate these Q values myself?

Thanks,

Mark