Thanks, This helps "Charles R. Patton" wrote: > > > This approach sounds fine. One variation that might be interesting is > to mount the radiating panel on the boom, but make that panel out of > double sided PC board. Drive it with a center-tapped RF transformer. > That way your 180 degree phase is on opposite sides of that panel and > you can resonate the capacitance of the panel easily, which makes > driving it easy. Now the pick-up plates will be stationary and close to > the detector circuit and easily shielded with short lead lengths and you > can null their output with simple summing which is then fed to a > synchronous detector (an RF mixer) in order to recover the direction of > displacement. A quick question at this point. I had thought about driving the two stationary plates using the centre tapped transformer and have the receiving plate move as there would only be a single detector instead of two that would need to stable and matched with respect to each other. But perhaps this isn't a problem if the two receiving plates feed the two opposite ends of another centre tapped transformer. This transformer would have two identical coils wound in opposite directions and the centre tap connected to the receiver/detector. With the radiator centred the two receiver plates would have identical voltage and opposite phase and the two oppositely wound coils on the detector would cancel each other. Through in a couple of variable resistors, or whatever to balance the detector circuit initially and it should stay balanced. Comments? Ron __________________________________________________________ Public Seismic Network Mailing List (PSN-L)
Larry Cochrane <cochrane@..............>