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Super Modulator
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22,493 Posts
Are you talking about the transistor to invert the "sense" of the chuff circuit? I think it was an NPN like a 2n3904, but I have not seen the circuit, and would be loath to recommend how to do it. I think you want the circuit that Stan used. As I understand it, he did not use a resistor to the base, nor a resistor on the emitter. Somewhat sketchy.

Regards, Greg
 

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Super Modulator
Joined
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22,493 Posts
Bob, 2n2222 or equivalent... connect base to bachmann chuff pin, emitter to ground, and use collector to go to your sound board. If you sound board does not have a pullup resistor, add one to the sound board input, 22k to plus voltage should be fine. Be sure to connect the ground on the bachmann board to the ground on your sound board.

Regards, Greg
 
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