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Pulling my hair out!! 555 circuit. please help

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illconductor

New Member
Hi i am trying to make a square wave oscilator, but its just killing me!
R1=10k
R2=100k
R3=1k
C1=10uF
555 mark to the right
6vdc supply

when i hook on the supply the led blinks then stays off. when i discconect and reconect suplly led stays off. when i dischrage the cap manually with the suplly off then reconect the led blinks like before.


This astable 555 circuit is the same diagram anywhere you look on the net so it must be right, just dont get it.

555 and 556 Timer Circuits

Would really appriciate help thanks.
 

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AllVol

New Member
1. Are you sure the 555 is oriented correctly - V+ to pin 8, pin 1 to ground?

2. Try taking the LED to ground rail instead of sinking from positive rail. Make sure LED is oriented correctly (long leg is anode)
 

Boncuk

New Member
You obviously shorted the output pin (3) to pin6 with a resistor. Put the 100Ω? resistor off pin3 sideways away from any other pin of the chip.

I suggest to rip up the entire circuit and start all over.
 
Last edited:

jpanhalt

Well-Known Member
Most Helpful Member
Also, you may need to add a 0.01 uF capacitor from pin5 to ground.

John
 

illconductor

New Member
yeah cheers guys it ended up being too high resistance r1 and r2. should be more like 1k and 10 k for 6 volts not 10k and 100k.
 
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