Weird LED circuit problem

[Wotan]

Here's the problem- I have made this circuit-




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.

 

[BobK]

You need a resistor in series with the LED.

https://www.electronicspoint.com/got-question-driving-leds-another-work-progress-t228474.html

Bob

 

[DrPinky]

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]

I have put a resistor in the circuit, it's still doing exactly the same thing.

 

[(*steve*)]

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]

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*)]

measure the voltage across the power supply pins (1 and 8) and tell us what is happening.

 

[Wotan]

I'll get back to you on that Steve, I need a decent power supply first.