False trigger in a 555 based on off circuit

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lubnaan90

Joined Jan 13, 2010
198
Have you tried adding a 10nF to 100nF cap from pins 2 & 6 to ground? That might desensitize it to transients.
Hello RON, It worked, I really wish that you had suggested this method earlier. Doesn't matter Now, I would like to Thank you for this Useful Help.
 

Wendy

Joined Mar 24, 2008
23,415
It basically increases the debounce duration. I never thought to ask about your switches. I'm pretty sure it was mentioned in the theory of operation in my article, hind sight being 20/20.
 

Thread Starter

lubnaan90

Joined Jan 13, 2010
198
Problem Solved!!!!!!
I would like to thank all the members for participating in helping me.
I would specially like to thank Ron H & Bill Mardsen for their intense help. Thanks.
 

Ron H

Joined Apr 14, 2005
7,063
It basically increases the debounce duration. I never thought to ask about your switches. I'm pretty sure it was mentioned in the theory of operation in my article, hind sight being 20/20.
My purpose was to lower the impedance of pins 2 and 6 to fast transients from sources other than the switch. That is in effect between button presses.
 
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Hey all, apologies for resurrecting an old thread (really old) but I wanted to say thanks to those who posted advise, it's solved a real headache!

I've got this circuit in use in an automotive setup - 6 copies of it in fact made up into a PCB. Despite bench testing it with a reasonable load, I didn't replicate the length of wires used which I would assume brought this to the surface.

Adding the cap between pins 2 & 6 and ground solved the false triggers but exacerbated the random startup state. That was solved by adding the cap and resistor to pin 4. I've also added the cap to pin 5...just because. I only made the changes to one of the copies of the circuit just so I could prove that the changes really had solved all of the faults, and yes! It had, really pleased.
 
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