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simple Time delay relay circuit

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Fletcher

New Member
I need help, want i want is a very small circuit to detect 5v and then to turn on a 5v relay about 5-7 seconds later.

Does anyone have any links or ideas?
 

Sebi

Active Member
I've not calculate the condenser, the value about 10uF. For exact timing You can experiment also with the charge resistor (68k).
 

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mozikluv

New Member
time delay computation

:D hi,

here's the formula you can use to compute the time you would want:
T = 1.0986(RxC) time is in seconds

using the 10uf cap
w/R = 68K - 7.4s, 62K - 6.8s, 56K - 6.1s, 51K - 5.6s, 47K - 5.1s


to sebi, i also had made a circuit somewhat similar to that, i used an SCR to drive the relay. :)
 

nettron1000

New Member
I see the point with the time delay circuit but Fletcher also wanted the circuit to first detect 5 volts and then delay the turn on time of the relay. I think a comparator voltage level detector would come in handy here. It appears the delay circuit would also require some means of initializing the delay when the 5 volt level is detected.
 
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