Help with circuit

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Swys
Posts: 3
Joined: Thu May 22, 2008 10:01 am

Help with circuit

Post by Swys » Thu May 22, 2008 12:35 pm

Hi all!

I am in need of help with the attached circuit. this circuit is for a backup for a traffic light. When the mains power is connected, the battery is charged and the light shines continuously. When the mains power is cut, the circuit activates the 555 timer and in turn lets the traffic light blink.

The problem I am having, is that when the mains power is cut, the circuit initially does as it should. After a short while, the time between blinks increase and then the light just suddenly turns off.

Please, can anyone help me with this? I am completely stumped...

Swys
Posts: 3
Joined: Thu May 22, 2008 10:01 am

Re: Help with circuit

Post by Swys » Fri May 23, 2008 8:13 am

:oops: It seems I forgot to attach the circuit, anyway, here it is!
Schematic.JPG
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Swys
Posts: 3
Joined: Thu May 22, 2008 10:01 am

Re: Help with circuit

Post by Swys » Wed May 28, 2008 10:31 am

I've found the problem. For anyone maybe struggling with the same sort of problem...

I noticed that I had too much input current for the 555 IC to handle. I just put a 1k current limiting resistor at its input, and now it works fine :D

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