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weird led question. please read details. Answered

This is very odd, I was soldering some leds earlier and when the iron touched the positive lead of the diode and i touched the negative lead the led would light up. It was very dim but the light was there, i took a video of it aswell. I want to know why this happened? I find it very weird. After years of working with leds Ive never seen anything like this. any light shed on this topic would great.?


What kind of soldering are you using?

Some heat by a heating element conducting the heat up the tip.

Others run current through the tip to heat the tip and although to you it is a dead short it may be a circuit to the led.

Put up a pic of the soldering iron or the make and model number to be sure.

This is probably caused by a badly earthed soldering iron with a fault or just bad insulating in it. A slight voltage leak from it would of been traveling from the soldering iron though the LED and down to the ground through you.



That sounds very likely! Would you have an explanation ad to why the led would also light up when I held the positive lead and touched the negative lead to a ground on a circuit board? Thank you

For the LED to light electrons must be passing through it. So the electricity is coming from some where.

You may have some kind of electrical fault in your home that provides the small flow required - Depending on the type and colour of the LED around 0.7 volts will do it at 2 or 3 mA.

You should try this in other parts of the house as well.

More than likely your earth system is not low enough resistance and this is earth leakage current.

I meant to reply to your onew comment but instead voted lol I cant reply to that one now for some reason, any way its a 25 watt radioshack brand. I have a weller 30 watt that i also use. wait, the ground on the soldering iron cord is broke off, I just notice this. I didnt break it off, could that be something?


Or you have built up your charged personality over the years :)

I agree with benmurton... your iron has a defect causing voltage to pass into the metal tip. This is bad. Anything you solder might be DAMAGED from the voltage going into the circuit. ALSO it is a SAFETY hazard because you may be shocked! I would destroy this iron if it can not be repaired.... and throw it away. Why destroy it??? so nobody finds it in your trash can and tries to use it, not knowing it is dangerous.

i never realized it could be a safety hazard. Thanks for the heads up! I will look into it more today. Ill replace the tip and see if anything happens if not Ill take it apart and clip all the wires.