I have a circuit where I am trying to replace a tactile switch with relay.
Instead of a reed relay, I thought I might be able to do this with a pair of parallel npn and pnp transistors.
The two terminals of the switch I want to replace have the interesting behavior that the polarity can flip; one terminal can be high while the other is low, and also the opposite. For this reason, one transistor by itself won't work as a switch replacement.
I tried doing this with a 2N3904 and 2N3906 tied together (emitter to emitter, collector to collector, and base to base), but it did not work as expected. With a 150 ohm resistor in series with the collectors and a 5v supply, tying the base to 5v allowed a current significantly greater than (5/150) A to flow.
Any suggestions?
Instead of a reed relay, I thought I might be able to do this with a pair of parallel npn and pnp transistors.
The two terminals of the switch I want to replace have the interesting behavior that the polarity can flip; one terminal can be high while the other is low, and also the opposite. For this reason, one transistor by itself won't work as a switch replacement.
I tried doing this with a 2N3904 and 2N3906 tied together (emitter to emitter, collector to collector, and base to base), but it did not work as expected. With a 150 ohm resistor in series with the collectors and a 5v supply, tying the base to 5v allowed a current significantly greater than (5/150) A to flow.
Any suggestions?
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