Hey
I've built a metal detector using a colpitts oscillator. I used two 1uF capacitors in series. When I bring metal close to the coil, the amplitude of the oscillations goes down to zero.
Can anyone please explain why this happens? Someone told me that it has the same effect as placing a resistor in parallel to the inductor, and in simulation this works very well..but i still don't understand the reason for this effect!