electronics experts

[pete_clio]

why will both of those not light. one or other but not both, tested bypassing the resistor.

i am however only using a volt tester to light them.

 

[biojo]

cant see where the negative comes in, but cant u just run them parallel, failing that maybe ones faulty?

do them circuit boars run in columns all joined cos if they do yer not actually using the resister, or are they wired on under side

 

[pete_clio]

yea they run in columns. im trying to run them in parrellal.

they both work just not together. im thinking there isnt enough current from the testor to do both?

 

[biojo]

well if they run in colums u would need to break the circuit underneath the resister,

Then the bottom led would need moving to the same column as above,

is it the top or bottom one that isnt working

in theory if there wasnt enough current i would expect niether or both to light dim

 

[sn00p]

yea they run in columns. im trying to run them in parrellal.

they both work just not together. im thinking there isnt enough current from the testor to do both?

That's not parallel how you've got them wired, that's series.

Need to know:

1) The input voltage
2) The LED forward voltage
3) The supply voltage
4) The current consumption of the leds.

 

[pete_clio]

they all just blew there when i put it on a 12v supply. need a higher resister me thinks!

EDIT...just realised i said parrallel...i mean series!

 

[rory182]

lol you dont put 12v onto an led, resistors FTW

 

[biojo]

but even on that setup with the right resister, surely the track under neath just cancels out the resister

 

[JON13S]

but even on that setup with the right resister, surely the track under neath just cancels out the resister

yeah track has to be cut below the resistor

 

[pete_clio]

my god,im thick...ill admit it, i never even twigged!

its working now though! lol
is 82ohms fine for bringing 12v feed in a car down to 3-4?

 

[richy22]

I think I can guess what this is for!

 

[biojo]

blue leds under the arches??

 

[ChrisR]

lol yeah as said the track that's in between the resistor points/nodes/whatever they are called needs to be removed. Else the flow will just go down the track as that's the path of least resistance.

I think anyway :/

 

[Dink]

i'd run them in parallel tbh

just so if you got a bad led/solder joint you will only lose one led that has the prob

 

[KDF]

Not only that but if one of the LED's short circuts then the voltage going to the rest of the LED's will be too high and cause them to blow or at the very least shorten their lifes.

 

[pete_clio]

I think I can guess what this is for!

haha :star:

lol yeah as said the track that's in between the resistor points/nodes/whatever they are called needs to be removed. Else the flow will just go down the track as that's the path of least resistance.

I think anyway :/

from memory of technology in school...thats right!

 

[sn00p]

Personally I'd trump the lot of you and run them from a microcontroller on PWMs so that they can have brightness. (or if I was feeling particularly geeky I'd break out an FPGA)

I (heart) embedded stuff.

 

[ChrisR]

I used to love doing embedded stuf at uni, assembly language ftw

 

[Floridadaz]

Generally components go on the other side of the board- I know the LEDS are surface mount but so this might be a bit difficult. You can bridge between 2 vertical tracks with the resistor so you wouldn't need to cut the track.