LED's

[MetalMaxima 10+ year member]

Stupid question time, but don't you have to use resistors when using LEDs?

 

[req 5,000+ posts]

yes and no.

if the LED's add up to the voltage you are using (in this case 12-14.4), then no. our leds are 3.2v each, 14.4\3.2=4.5

so id be comfertable with eaither 4 or 5 leds per chain. but if you wanted individual lights, you would need a resistor of the proper ohm-age (lol) to cut that 14.4 to 3.2v - and dont forget, the car is at 12ish volts when off, and 14.4 when on, so the LEDs wont be as bright (if you wire them together-or individually) when the car is off.

 

[MetalMaxima 10+ year member]

Wow, thanks REQ, that's really informative! How about circumstances where one would be running multiple LEDs on a breadboard, say 20...you would not need resistors? (fingers crossed, this would make things wayyy easier! //content.invisioncic.com/y282845/emoticons/tongue.gif.6130eb82179565f6db8d26d6001dcd24.gif )

 

[req 5,000+ posts]

get a breadbord with a 12awg wire (fused) going to the fuse box on the switched line.

hook up several leads (depending on how many lights you need) on each lead, wire 4 LED's in series (as seen in the pic on the previous page) and mount them wherever you want. and put a switch in series on the ground wire - mount at your disgression.

no resistors needed.

//content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

 

[MetalMaxima 10+ year member]

Aren't they kind of big? I am going to be trying something where I cut a plain-jane breadboard and cut it o a semi-circular shape and mount it behind my insturments cluster gauge...would I be able to do that with the kind of board you are referring to? //content.invisioncic.com/y282845/emoticons/confused.gif.e820e0216602db4765798ac39d28caa9.gif

 

[req 5,000+ posts]

yea, you can use 3mm LED's... heres a pic.

a pictures worth 1000 words.

oh yea. this would be bright as ****.

you can extend the blue lines as far as you like.

 

[ANeonRider 10+ year member]

Find some prototyping board, with the pads on it. You can find it at radio shack.

 

[Buckshot 10+ year member]

LED Experiment uno.

I then ran stripped wire to all the posy's and all the neg's. Added a resistor, and BAM! Blue LED's for my Xbox.

 

[Buckshot 10+ year member]

BTW, I bought my LED's From LSdiodes, AND they sent me a free robot sticker. //content.invisioncic.com/y282845/emoticons/yumyum.gif.0556df42231b304b9c995aefd13928a8.gif Oh oh oh! I got the resistor at radioshack, and yeah, I think thats it, I can take a pic of the wire and shit if you want...

 

[jrz126 10+ year member]

It's good practice to wire in a resistor though.

And you dont install the resistor to cut the voltage down necessarily, you use it to regulate current. Most LED's are designed to handle a constant 20mA. You use ohms law,

R=V(at resistor)/I. The voltage at the resistor is Battery voltage-forward voltage of LED.

So if you have a LED with a forward voltage of 3.2V, it would be (14.4-3.2)/.020A =560 ohms. or if you had 2 leds, 14.4-3.2-3.2/.020 = 400 ohms.

and while we are showing off LED projects...

The backside...

one of 2 circuit boards to handle the high current

and the pic in my sig shows the final product...with an added effect from a fog machine...