Charles Linburgh deadmans button

ecopure said:

Hi everyone, just joined and love the place.

I've been trying to figure out how to make a timing circuit that will stay "latched" as long as someone pushes a button every 10 minutes. If the button isn't pushed the timing cycle stops and an alarm goes off.

When Linburgh flew across the atlantic he had alarm clocks to do this. I would like to make one out of a 555.

Any help would be appreciated

Thanks
Steve

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MikeMl said:

Here you go. Output goes high on the first trigger, and stays high only if the button is pushed before the 555 times out. It is set for about ~600sec. R2 is there to limit the discharge current through the switch.

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haris_216 said:

I think that one kind of warning (visual or audio) that 555 is about to time out (giving 20 seconds for example) would be helpful

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