Latching circuit using PNP and NPN

189

08:09:59

A simple circuit controlling current to a load using 2 transistors and 2 momentary buttons.
The circuit latches on because the PNP is draining through it's gate, through the NPN and the load. Because it's draining it's also holding the NPN's gate high.
Pressing the bottom button pulls the gate of the NPN low, preventing it from sinking current through the gate of the PNP. Because the PNP is no longer draining it also stops sourcing current to the NPN's gate.
Pressing leftmost button brings the NPN's gate high to sink again latching the circuit back on.

published 8 years ago

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