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Weird LED circuit problem

Wotan

Oct 8, 2011
37
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Oct 8, 2011
Messages
37
Here's the problem- I have made this circuit-

555_Timer_1 LED blinker.jpg


But as soon as I connect the supply voltage, the LED blinks as it shoud for about 1/2 a second and then stops working altogether. Could this be because the connection from the supply voltage is not very good? I had to replace the battery clip I was using because the wirse on it were too thin and weren't making a proper connection.
 

DrPinky

Nov 7, 2011
22
Joined
Nov 7, 2011
Messages
22
You might have burnt out the LED, I tested the circuit on Yenka and it burnt the LED out. BobK is right you probably need a 390 Ohm resistor.
 

Wotan

Oct 8, 2011
37
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Oct 8, 2011
Messages
37
I have put a resistor in the circuit, it's still doing exactly the same thing.
 

(*steve*)

¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd
Moderator
Jan 21, 2010
25,510
Joined
Jan 21, 2010
Messages
25,510
1) what value is your resistor?

2) what do you mean "altogether"? (until you cycle power, or until you replace it with a new one?)
 

Wotan

Oct 8, 2011
37
Joined
Oct 8, 2011
Messages
37
1)The resistor connected to the LED is 470 ohms.

2) The LED blinks and then fades until it is no longer lit. The LED works ok I have tested on it's own, separately to this circuit.
 

(*steve*)

¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd
Moderator
Jan 21, 2010
25,510
Joined
Jan 21, 2010
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25,510
measure the voltage across the power supply pins (1 and 8) and tell us what is happening.
 

Wotan

Oct 8, 2011
37
Joined
Oct 8, 2011
Messages
37
I'll get back to you on that Steve, I need a decent power supply first.
 
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