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Hmm what's wrong?

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Gene

New Member
The wire coming from pin #7 is wrong - it should connect to 2 resistors instead of one.
 

kinjalgp

Active Member
I think you have wired 555 in monostable mode or you are missing something. The circuit seems ok except that you have not connected a capacitor of 0.01uF between pin 5 and ground which prevents spurious triggering of 555 due to noise.
 

daviddoria

New Member
hahaha i am retarded. i had R2 connected to 8 instead of 7.

sorry for bothering you with this sillyness :)

kinaljp, maybe i'm just lucky, but i've done several things like this without the cap on pin 5 and i've not seen a problem....
 

pebe

Member
bogdanfirst said:
the cap on pin 5 is for frequency compensation....
use it only on highter frequencies
Pin 5 is made available so that you can externally modify (for a variety of reasons) the potential divider used by the two internal comparitors.

In almost all cases you don't need a capacitor there - you can leave it undecoupled.
 

daviddoria

New Member
just for feedback: it seems to work with a 1k resistor. duno if its because of the tolerence that it is close enough to 5, or what the deal is. just letting you know.
 
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