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555 chips, powering up

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planty

New Member
When you first power up the 555 chip in a small kit , it works straight away, but can you stop the unit from working every time you power up, but it still will work on it's trigger input?

I thought it would be a small cap on pin 2 or 4 but the unit still works when powerd up,
Thanks, David
 

KMoffett

Well-Known Member
Can you post the schematic?

Ken
 

planty

New Member
8931-totalclosurehelp.jpg


this does work fine at the moment, i just dont want it to work when it gets powered up.
 
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KMoffett

Well-Known Member
Sorry, but I can't read the small fuzzy image. Can you convert it to a larger size in a GIF or PNG format. They give better detail with a smaller file size.

Ken
 

audioguru

Well-Known Member
Most Helpful Member
Please attach the schematic here intead of over at Photo-Bucket.
 

planty

New Member
picture as asked..
I think i have done it;.
also i have put 4700uf cap on the pos and neg just to give me a few extra seconds.
The kit is to close a car roof but i didnt want it closing when you start the car as it can take all the power as start the car then closing the roof.
 

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audioguru

Well-Known Member
Most Helpful Member
The schematic was originally made as a fuzzy JPG file type. Converting it to a different file type does not remove the fuzziness. It should have been made as a very clear GIF or PNG file type in the first place.
 

BrownOut

Banned
I guess you mean you don't need help, since you have "done it." But if you have problems again, you may use the reset pin ( pin 4 ) to prevent the timer from operating on startup. Just use a capacitor and resistor to apply a short reset pulse until the operating voltage settles.

EDIT: On second thought, you probably want to use a short pulse generated from a logic gate or transistor to reset your timer. (Been reading the turtorial)
 
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