Re: DABAR mystery circuit
It should act as a filter giving a peak whose frequency can be varied with a foot pedal on the resistor in the T network. The resistor in the emitter controls the height and sharpness of the peak by setting the transistor's gain.
A bridge-T network acts as a notch filter. this bridge-T is in a feedback circuit around a transistor amplifier. Outside of the notch, feedback reduces the amplifier gain. inside the notch the gain is not reduced. so an active circuit transforms a bandstop function into a bandpass.
David
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Can't afford the volcanic island yet, but the plans for my monorail and the goons' uniforms are done
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