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555 timer help!!!

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edisonboy

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I am trying to make a 4 second delay on a 555 timer circuit, so that when I put power on it, it will start out dead, wait 4 seconds then turn on forever. All help is appreciated.
 

edisonboy

New Member
could you tell me more... I just tarted this 2 days ago

could you tell me in a bit more depth (like pin numbers)?... I just started 2 days ago... :oops: I'm working on reading scimatics (any tips on that will also be appreciated! :D ) but they still look alitle confusing...

thanks

Ed
 

Russlk

New Member
This is what I had in mind: The 4 second time is set by R1 and C2, the trigger is caused by C2 which holds pin 2 low at the time power is applied. C2 charges thru R2 in less than 4 seconds so the timer does not re-trigger. C3 is just the recommended bypass cap. The output of the 555 does not go all the way to the power supply voltage, so the yellow LED is used to drop 2 volts and insure that the 2N2907 is off when the 555 output is high. Any questions, you can email me or post here.
 

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