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how to make an adjustable 5 minutes timer without microcontroller?

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gardenyu

New Member
I was recently assigned this project. Build an adjustable timer to count as long as 5 minutes ( accuracy is not important) then trigger something.

Although programming a micro would have been easier, I rather not do that for now. But normal 555 and RC timers can only count very short time period.

Any suggestion?
 

kpatz

New Member
The 555 can time intervals more than 5 minutes with a big enough capacitor/high enough resistors.
 

gardenyu

New Member
Thanks, but this is for a LED circuit which is supposed to be operating for 50,000, I don't think large electrolytic caps is suitable there.
 

crutschow

Well-Known Member
Most Helpful Member
Use a 555 timer at a higher frequency and use a counter to count the 555 clock pulses. For example an 8-bit counter would give you a 5 minute period with a 256/300 = 0.853Hz frequency from the 555. A 16-bit counter would require a clock frequency of 218Hz.
 

microtexan

New Member
supposed to be operating for 50,000 50,000 what?
 
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