555 Timer Not Working Correct

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

aha!!!

how silly of me ...im soo ashamed

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 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