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How to use 555 to start some circut in delay?

JakubPrazmowski

Ok. I got monostable mode. I am pressing my little button and timer starts rolling. I getting HIGH on output 3 and it last some time. I wonder why how to connect it with some other circut to start rolling just after state from pin 3 will go back to LOW? 

I am new in electronic so any help is very welcome. Thank you very much for help.

Jakub

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    it depends on the exact use case - would it be an one-time delay after power-on? or a delay after button press? what would be an default state of output (for example: default low, goes high after defined time from button press and stays high forever/for defined time/until some other action)? There are many such circuits when searching for "555 delay timer" on the Internet with different schematics for different use cases...

  • 0

    You can use a dual 555, which would be a 556. The first monostable triggers the second monostable to start after a delay.

  • 0

    The datasheet for the TI NE555 gives this for a sequential timing circuit.

    image

    Have a look at the datasheet for the output waveforms and more details.

    www.ti.com/.../NE555

    They've used a cap and resistor as a differentiator between the stages. If you've got an oscilloscope, it would be worth slapping it together on a
    breadboard and looking at the waveforms. If not you could try a simulator.

    One question you might ask yourself is, how is it safe to use the differentiator like that, given that it will produce a positive spike on the
    other edge (that would take the TRIG input above the supply)?