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Topic: 8x8x8 multiplexed LED cube with an Arduino Mega 2560 (Read 41 times) previous topic - next topic

Un4Seen

Quote
Why don't you take a AC voltage reading between your iron tip and an independent path to your power ground when the iron is turned on


In other words take an AC voltage reading with a multimeter between the iron's tip and the grounding in the wall socket?
The iron doesn't need to be turned on the light the LEDs when touching them. I just needs to be plugged in.

I wonder if I can demand changing it in the store because of this... I mean, is this a defect or it's just a poor model?

retrolefty


Quote
Why don't you take a AC voltage reading between your iron tip and an independent path to your power ground when the iron is turned on


In other words take an AC voltage reading with a multimeter between the iron's tip and the grounding in the wall socket?

Yes
The iron doesn't need to be turned on the light the LEDs when touching them. I just needs to be plugged in.

Turn the iron on for the test, but no LEDs required, just measure for AC voltage from tip to ground while powered up. Obviously you can't leave your meter lead on the hot iron for too long.

I wonder if I can demand changing it in the store because of this... I mean, is this a defect or it's just a poor model?

Make the test first. I searched a little for this product description but can't find anywhere where it states it's a grounded iron tip or that it offers ESD protection which is the same thing.
Lefty



Boffin1

#117
Feb 07, 2013, 08:06 am Last Edit: Feb 07, 2013, 08:08 am by Boffin1 Reason: 1
Using the soldering techniques described by some of the guys above (  pretinning the legs, and then just reflowing the solder whie holding the legs still until the solder goes a dull colour again )  I soldered over 8000 joints on my last project without losing one LED.

For my sins, I had to get 2 prototypes out before the PCB manufacturers opened after their Xmas summer holiday break ( everything shuts in South Africa for a month )  so I built them " dead bug " style.

During the days of boredome at the bench, I calculated that I had spent over 10 hours in total just holding the wires steady until the solder set !

Heres a pic of a couple of the 60 dead bug chips and LEDs     -  DONT TRY THIS AT HOME FOLKS !

With my mobile phone I can call people and talk to them -  how smart can you get ?

Un4Seen

Thank your for the replies, guys! I will do that test tonight, I'm curious what I will find.

Un4Seen

Hello again!

I did some more tests and... I'm even more confused :|

First of all, I measured the voltage between the tip of the soldering iron and the wall socket's grounding. I've set the multimeter to 750 V AC and tried it. The result: 90 V! Wow! I know that there's no error in my measurement because I tried measuring the mains voltage with the very same settings and I got 230 V, which is the standard value here in Eastern Europe.
Next I took another old soldering iron, which does not have grounding. With that one I obtained 45 V.

You know that what I initially observed, yesterday, was that if I touch either leg of the LED with the tip of the iron and the other leg with my finger, the LED lit up (although it was dimmer than usual). So I thought to myself, let's try to ground the tip of the iron by connecting it with a wire to the wall socket's grounding. And this is when the real surprise came! The theory was that the current will not go through the LED, it will go through the wire directly to the wall grounding and the LED will not light up. Instead the LED lit up twice as bright! Remember that I was still touching the LED's other leg with my finger.
Next I completely took out the soldering iron from the equation. I just held one LED leg with my fingers and I connected the other LED leg directly to the wall grounding through a wire. The LED still lights up, although not as strongly as through the soldering iron.

So what is going on here? Am I producing electricity and it's flowing through the LED into the wall grounding? And for minutes and minutes, without an end? How can I be producing electricity constantly? OR is the electricity coming from the wall grounding and going into me?
I tried holding the LED and connecting the other leg to some other mass, like the radiator, that way it does not light. But if I connect one leg to myself and the other leg to ANY wall grounding in the apartment, it lights.

What's going on here? The only thing I can think of is that the wall grounding is not done properly and that it's leaking very small amounts of current at 90 V...

I'll try taking the LED into another home in a different part of town, let's see what happens.

What a stupid game of circumstances that lead to the destruction of my 4x4x4 cube!

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