555 timer circuit

I'm trying to build a 555 or 556 timer circuit that creates a 5 second pulse to activate a small reed relay every 5 or 6 minutes. Can anyone help me with that. Thank You. John

In message , John Winstead writes

You'll have trouble getting a 555 to run that slowly. You'd have to use a very low charging current for the capacitor, and it may be less than the capacitor's leakage current.

I'd use a 4060 (

) to produce a pulse every 5 or 6 minutes then use that to trigger a 5 second monostable. I seem to recollect that the 555 can be used as a monostable and 5 seconds would be do-able.

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Graham

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If you can live with the nominal 5 seconds VS 5 minutes ratio being fixed you don't even need the 555:

Q(N) ---/\\/\\/-----+------------- Reset ! V --- ! Q(N+A) -------------+-------------- Pulse

Q(N) needs to be such that it has a period of 10 seconds so that it will be low for 5 seconds after Q(N+A) goes high.

From the reset, it will be 10 seconds times 2^A until Q(N+A) goes high. It will then remian high for 5 seconds. If you make A 5, the full cycle will take 325 seconds.

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kensmith@rahul.net   forging knowledge

So you want it to work in astable mode with Tl = 5min and Th = 5s

It's not that hard, read the datasheets.

See my reply in sci.electronics.basics, pointing you to this solution:

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Terry Pinnell
Hobbyist, West Sussex, UK

[...] A slight change:

You don't need two diodes.

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kensmith@rahul.net   forging knowledge

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Clever. :-)