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555 Timer Not Working Correct

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Kane2oo2

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Hello
I have built a 555 Astable circuit (if anyone has livewire it is the 555 circuit from there)
I built the circuit but not having any potentiometers/var resistors around i used a 20k fixed resistor instead.
Now i have also not got the top led in place but have one connected from the output to negative with a 560 resistor after it (didnt have a 680 around)

And the problem is ...the led comes on ...but it doesnt flash!

Any Ideas?
Also what is the "charging" connection for?

Thanks
Kane
 

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Kane2oo2

New Member
aha!!!

how silly of me ...im soo ashamed :oops:

the power supply i am using (i dont think its a clean source)

it is from an old (very old) train set rated at 12 volts....

so i put a 100uf capacitor over the contact and guess what!!! the circuit works :p lol

now is this becuase of the power supply or was the circuit flashing because of the capacitor? i dont quite understand what i did ! lol

Could someone please explain?

Kane
 
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