Turn Circuit On/Off With Momentary Contact

martianman said:

Hello All,
I want to turn a circuit on and off using a momentary contact switch. I have a 4011 NAND Gate and and CD4027BE flip flop but every circuit diagram I've found doesn't do what I want. I'm using a 5v and 500mA power source. Any help is much appreciated!

P.S. I only want to use 1 switch. I found a circuit that used 2 bits with 2 switches using a 4011 NAND Gate: one set and one reset. This is not what I want.

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martianman said:

Hi Eric,
I tried out your circuit in a few different ways and I couldn't figure out how to work it correctly. Let me give an example to make this easier for me. I want to use a 4027 or 4011 IC with one momentary contact switch to turn on and off an LED with one push.

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Mike2545 said:

This is a nice little chip that will handle up to 8 buttons.



**broken link removed**

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blueroomelectronics said:

It's a preprogrammed PIC Probably a 16F627

I'll have to check out the EDE product line.

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martianman said:

Ok I tried the second diagram you gave me Eric; that one didn't work for me either. Maybe I'm just hooking it up wrong... Could you give me a diagram with the pin names and pin numbers? I'm extremely confused here...

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hdc090360 said:

Using a momentary contact switch in Eric's circuit is always dodgy.

They normally produce a stream of pulses "switch bounce" and your output will be random depending on whether you get an odd or even number of bounces big enough to toggle the flip-flop.

Try putting a cap (1-10µF) across the switch or a debounce circuit using your 4011 chip.

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