Troubleshooting My Timer: Why Won't My Relay Open and Shut?

AI Thread Summary
The timer is not functioning as intended to open and shut a relay periodically. The output appears to be directly shorted to ground, which may be a critical issue. Disconnecting the output from the ground could allow the timer to sink the current properly. Calculations indicate that the 555 timer should be able to handle a sink current of about 11mA. Proper configuration and connections are essential for the timer to operate correctly.
simo
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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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simo said:
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?
 
berkeman said:
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?
 
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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