Latching Momentary Switch for breadboard

I found simple and cheap  “Latching Momentary Switch” circuit

Original article

When the circuit is powered up, all of the transistors are off and stay off. C1 gets pulled up to Vp.  When the switch is pushed, Q3 and Q2 turn on, since their base is pulled up. Q1 and Q4 are in turned on as well.  Q1 keeps Q2 turned on and Q2 keeps Q3 turned on and Q3 keeps Q4 turned on.  Q4 supplies current to the load. When Q2 is asserted it keeps pin 1 of SW1 at ground. 

When the switch is pulled low again, the base of Q3 is tied to ground, because Q2 is on, and the chain is broken an all of the transistors turn off. 

C1 and R1 and R5 form the time constant for the debounce circuit.  Adjust these values for an appropriate debounce time.

In my version came out the following scheme.



I made a board by my own technology

Released the next device. Current consumption in off 1µA!!

IMG_1456 IMG_1458

Video of work process

Progect of button in Eagle




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