Led and resistors
 

Can you wire multiple 5mm LEDs to one 150ohm resistor? Or do you need multiple or a bigger resistor?

Re: Led and resistors
 

if you are wireing multiple lights to the same circit you dont need a resister if you run off a 6v bec just wire them in sieries they efectivly act as resistors all by them selfs just have extra bulbs on hand just incase you blow a few

Re: Led and resistors
 

Use something like ledcalc.com to figure out all your resistor needs for LEDs.

Re: Led and resistors
 

There's too much info missing to give you a good answer as is. As was already mentioned there's led resistance calculators you can use that will help you figure this out.

If you don't have the specific info for your LED's and you cant find it online, you can roughly assume that clear LED's want 4V and draw 20mA, red LED's want about 3.5V and draw about 20mA.

Single LED's:
http://led.linear1.org/1led.wiz

Multiple LED's:
http://led.linear1.org/led.wiz

Re: Led and resistors
 

I can do the math, have done the math, don't want to do the math...

This is why I buy Common Sense LEDs, they have a very wide voltage range and come prewired with resistors.

Re: Led and resistors
 

Don't be lazy ;-) Use one LED per resistor.

This will walk you through it all.
http://www.rccrawler.com/forum/elect...wire-leds.html

Re: Led and resistors
 

One led per resistor only works if they are wired in parralel. If you wire in series you want to limit the current with a single resistor for the string.
The resistor in either case depends on the voltage supply, the voltage drop of the led and the led current rating.
If you have a 12 volt supply and a led that drops 4 volts, you have a 8 volt difference. If the led was to be limited to 80 ma. You would need a (v=ir) 8/.08 = 100 ohm resistor. To limit to 20 ma you would need a 400 ohm resistor.
If you have multiple LEDs then add their voltage drops together and make sure your supply is higher. Then just pick a resistor that gives you the current you need.
If you go with high current LEDs then a constant current led driver would be better.

Re: Led and resistors
 

Alka I was thinking that about only needing one resistor when running in series. Thanks for the knowledge. I'm using a prewired light kit and adding light to it. So hope fully the 8
extra lights won't hurt.

Re: Led and resistors
 

But, from an electronics engineering standpoint you shouldn't wire in series because of the voltage drop across the circuit. Each bulb in the chain gets a little bit less voltage than the last one did. The difference is small, but across led's you can often see the difference in brightness.

Re: Led and resistors
 

You also wouldn't be using resistors from an engineering stand point.

From a practical stand point, we have limited space for power and even less for a rats nest of wires. Personally I'll use series as much possible too not only relieve those issues above but also, the entire circuits point is to create light, not heat.

Re: Led and resistors
 

Awesome thanks. I'm planning on NOT adding the lights to the existing set and stringing another set for rock lights and fog lights. That way it will eliminate the dimmer lights.