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555 Timer Circuit

wheelbrace

Nov 12, 2017
3
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Nov 12, 2017
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3
Hi,

Just wondering if I could get some help with my problem.

I have a simple 555 time circuit that powers a flashing LED.

This is for the inside of a car.

When I connect the circuit to the battery with a short power lead it all works fine.

However, when I put the circuit on a longer cable to be able to place the circuit inside the car the LED flashes once and then the circuit then stops working leaving the LED with a very faint glimmer.

I have no idea why this happens.

Thanks

Dave
 

Harald Kapp

Moderator
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Nov 17, 2011
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There are a few possibilities:
  • Do you have the stabilizing capacitor from pin 5 (CTRL) to ground in place?
  • Do you have a bypass capacitor from Vcc to ground in place?.
  • What kind of wire are you using? A long thin wire may have excessive resistance.
 

Bluejets

Oct 5, 2014
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What is the LED you are using?

When you say "connect to THE battery" ....which battery? The one in the diagram or the car battery?

Length of the cable you are using should make no difference as the circuit only draws a few milliamps.

Have you checked all your connections when you move to the car supply?

Show a pic of your final arrangement in the car with as much detail as possible.
 

wheelbrace

Nov 12, 2017
3
Joined
Nov 12, 2017
Messages
3
Ok,

Thanks to both for your replies.

The only battery I used is the car battery. I was messing around for ages checking for loose connections with no luck as I only have this assembled on a breadboard at the moment.

However, I just connected a 10nf capacitor between pin 5 and ground and it now works!

Thanks to both for your help and advice.

Cheers

Dave
 
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