555 timer

  • Thread starter simo
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  • #1
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Can you tell me what is wrong with my timer. I want it to make a relay open and shut periodically. For some reason it's not working.
 

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  • #2
berkeman
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Can you tell me what is wrong with my timer. I want it to make a relay open and shut periodically. For some reason it's not working.
You show your output directly shorted to ground. Is that correct, or a typo?
 
  • #3
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You show your output directly shorted to ground. Is that correct, or a typo?
Nope, that's how I made it.

If I disconnect the output/diode junction from ground, would it sink the current?
 
  • #4
dlgoff
Science Advisor
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If you do the calculation from the numbers you give, the sink current would be about 11ma, so the 555 should be able to sink that.
 

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