Electronics question (didn't know which forum!)

Docaroo · 4 Apr 2006 at 13:14

Hi guys,

I have here 10 red 5v LEDs and an old phone charger socket that was broken... I want to use the phone charger to power these LEDs and make a light out of them!

The problem (i think) lies in the mA rating of the plug. It has a 5v (4.9v) output and the LEDs are 5v so kno problem there, I can connect them in parallel and have a pretty lamp.. however the plug says on it 450mA whereas I only want between 10-30mA going to the LEDs.

Is this a problem? Or does the mA amount not matter in this case? This is the one part of electronics I never bothered to check up on lol... Thanks guys!

paradigm · 4 Apr 2006 at 13:16

The value on the plug will only be that which it "can" supply. If the LED's are only trying to draw 30mA, they will only draw 30mA.

Red and White · 4 Apr 2006 at 13:16

OMG GOD

your gonna kill yourself, throw them all away this minute

Docaroo · 4 Apr 2006 at 13:18

lol thanks dudes

both a useful and comical reply! best of both worlds...

well... here goeOSHE&G%B"N!&YT)%&YV"!EISAGT OBUAGRRRRGGGGHHH OIH MY GOD IT BURNSNRNFPSAIJSNFB N!H B(!"&%V!!&!!!1111111................................................

Jotun · 4 Apr 2006 at 13:22

I would have thought you'd need current limiting resistors...

Also they may not work well in parallel unless they all turn on at exactly the same voltage, otherwise the one with the lowest threshold will turn on first and all the current will go through that. Look at the specification of the LED though to find the maximum current, typically the ones I use are rated at 500mA, but they only need around 2v.

clv101 · 4 Apr 2006 at 13:23

Do we get a photo of the finished project?

Docaroo · 4 Apr 2006 at 13:23

they are all the same LED type... specially designed for 5v power supplies - should be fine! will let you chaps know if not lol

Docaroo · 4 Apr 2006 at 13:24

clv101 said:
Do we get a photo of the finished project?

yep

Red and White · 4 Apr 2006 at 13:24

clv101 said:
Do we get a photo of the finished project?

how can he take a photo when he electrocutes himself and his arms fall off?

Docaroo · 4 Apr 2006 at 13:25

press the button with my nose !

Jeff Crawly · 4 Apr 2006 at 13:45

paradigm said:
The value on the plug will only be that which it "can" supply. If the LED's are only trying to draw 30mA, they will only draw 30mA.

Exactly!

Unlike voltage a PSU will only supply the current it is asked for!!

Mickey_D · 4 Apr 2006 at 14:09

<----- electronics technician

I've done almost exactly what you're describing MANY times. As said before, the wall wart rating is the MAXIMUM it can supply, the LED's will only take what they need.

It's like in your car. The battery has the capabillity of supplying 1000Amps at any one time (granted for only a VERY short time), but your car stereo only needs 15 Amps to run at full volume. If you turn on the stereo, does it explode due to 1000 Amps being put through it? Nope, because it only takes what it needs.....

Red and White · 4 Apr 2006 at 14:12

he hasnt posted in a while

should have listened to me tbh

Docaroo · 4 Apr 2006 at 14:33

lol i tried it with one LED and it works ! - i'm building the light now!

I don't really have anything to build it in haha so I'm trying to find something to make it out of!!

Right now - I'm toying with an old tennis ball tube and a small headphone's holder tthing - not great tbh haa