diyAudio (
-   Chipamp (
-   -   noob: blue LED polarity (

Burnincoils 20th October 2012 04:22 PM

noob: blue LED polarity
2 Attachment(s)
Dual Mono 3886 kit ordered recently

alright i think i installed the blue LED backwards.

the long leg against the ">" arrow

from what i understood of the guide:
"arrow ">" this points towards where the long leg is soldered in.

multimeter gives reading(1.960) only when reversing the testing leads and dont light up LED.

when i was soldering the LED lit up briefly lol

is this a problem? is there another way to test it?


counter culture 20th October 2012 04:38 PM

A good way of testing LEDs is to use a lithium coin cell such as a 2016. I have dozens around here as I bought a batch of 50 keyring torches from to use as doglights.

You can connect the LED momentarily directly across the coin cell. They have ~3.6V out which is sufficient to cause any LED to strike, but so little current drive capacity that destruction of the LED is unlikely unless it has a VERY low power rating, I've never blown one up doing this.

Burnincoils 20th October 2012 05:21 PM

1 Attachment(s)
hey counter culture,

nice tricks!(they are avaliable everywhere) :) i will try them for sure, but i'm more inclined to just cancel the led.

can i install a jumper wire instead?

here you can see a picture of the led i removed just now

the long leg supposed to go on the left against the arrow?

Mooly 20th October 2012 05:29 PM

If the LED is just purely cosmetic then you can just omit it with no further action.
You say the LED lit while soldering ? You soldered with it powered up or with the caps fully charged ? If the iron was earthed then you could have a low resistance path via the iron that zapped the LED.

Burnincoils 20th October 2012 05:34 PM

the board is not in a condition to be powered up still

no the boards still not wired to ac.

i just saw briefly a blue flash reflected off the worktable

the iron is 2 wire so maybe its not earth? strangest thing... anyhow yeah i will check if it is cosmetic then i dont need this.

maybe the tip is somehow carrying voltage? (no idea about this making sense or no)

Marra 20th October 2012 05:35 PM

Leave it out and whatever you do do not install a jumper wire unless you mean to connect to an led on the front panel.

AndrewT 20th October 2012 05:39 PM

That little white arrow seems to be non standard.
A LED is a diode. We usually find diode symbols and orientation to be quite unambiguous.

The LED symbol with a part circle with one flat edge is used. That flat edge corresponds to the bar of the diode.

Burnincoils 20th October 2012 05:40 PM

alright thanks guys, i will not install jumper and just cut it off and if the boards not working(after ac on) i'll update so we find a solution.

pdul 20th October 2012 06:08 PM

Looking at the closeup it seems that you just have to turn the led around to get + on the long leg.

pdul 20th October 2012 06:09 PM

It is very clear that you have + on the series resistor

All times are GMT. The time now is 02:58 PM.

Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 18.75%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Copyright ©1999-2018 diyAudio