How to wire LEDs

[heyok]

Originally Posted by rdl77

Im planning to run 2 white led and 2 red led, and i have a bunch of 1/4w 1k resistor, is 1k to high for a 6v power source? Or can i use 1 resistor to run my 2 headlight in parallel?

You can use 1K but the LED will barely glow.
No to the second question.

[Olle P]

You can use several resistors mounted in parallel to reduce the resistance and thus get the right current to the LEDs. Seven 1k resistors in parallel should be fine for a 3V 20mA LED. Add three more for 30mA.

[nitro_star]

Just used your tut to do my own leds Heyok, couldn't have been easier. Thanks for the write up and knowledge. Anyone thinking of doing it should, its easy. Thanks again Heyok

[heyok]

You're welcome! Glad it could help some of you.

[KJ10]

Originally Posted by heyok

You're welcome! Glad it could help some of you.

Some of us don't say it when we use your info but, THANKS AL!

BTW, hope you have more no-brainer bec's ready. Gonna be ordering one for my SCX soon! Love the one I installed on my son's 1/18th and the custom dual-channel CC 20A on my super! Great work! Oh, the dual channel light controller works awesome, too!

[heyok]

Originally Posted by KJ10

Some of us don't say it when we use your info but, THANKS AL!

BTW, hope you have more no-brainer bec's ready. Gonna be ordering one for my SCX soon! Love the one I installed on my son's 1/18th and the custom dual-channel CC 20A on my super! Great work! Oh, the dual channel light controller works awesome, too!

Appreciate all the kind words! Glad I can give back.
Al

[craddock35]

Thanks for the help heyok you have already covered everything I was going to post in the thread I started plus some.

Maybe this can be made into a sticky so it will be easy to find for everybody.

[craddock35]

Ok I am having a little issue with some new leds I am trying and I am thinking resistors are the issue but the guy I am helping swears it isn't. We are using 8mm 0.5W High-power White LED Lamp Light 100MA running off a 3s battery. What resistors should we be using? I am thinking about a 470k ohm 1/2 watt and he says a 330k ohm 1/4watt resistor. I have never used this size led and from what I read I figure a 1/2 watt led needs a 1/2 watt resistor I could be wrong I guess. Thanks for any help.

He also wants to know if there is a way to make these work to their full potential using a axial simple led light controller that the rtr axial stuff comes with?

[heyok]

I'm afraid that your resistor values are too high.
Let's try this...
There is a handy tool called the LED calculator.
LED calculator for single LEDs

The source voltage = 12 volts (a 3S Lipo is about 12 volts)
The diode forward voltage = 3 volts (this is an assumption - most white LEDs have a forward voltage of 3 volts)
The forward current = 100 mA

The result of the calculation is to use a 100 ohm 2 watt resistor.

Hope that gets you some results!

[craddock35]

Originally Posted by heyok

I'm afraid that your resistor values are too high.
Let's try this...
There is a handy tool called the LED calculator.
LED calculator for single LEDs

The source voltage = 12 volts (a 3S Lipo is about 12 volts)
The diode forward voltage = 3 volts (this is an assumption - most white LEDs have a forward voltage of 3 volts)
The forward current = 100 mA

The result of the calculation is to use a 100 ohm 2 watt resistor.

Hope that gets you some results!

Yep that does it and I had just figured out where I went nuts on it. I was putting the wrong forward current looking at the specs for the wrong led for some stupid reason. One of those duhhhhh moments. Thanks
At least he was figuring wrong also. Now we just gotta find resistors.

[Tommy R]

Hey Al,

I've got a question for you and hoping you can help out. So as you know, I ordered one of your lighting control units and I decided to go to Radio Shack to pick up the necessary LEDs. Basically, I'm just getting a variety of 3mm and 5mm LEDs in white, amber, and red. A grand total of 10 that will run off my receiver output (6v).

Well, Radio Shack had no selection so I decided to try Digikey. But wow, it was quite overwhelming! The listings are huge and I couldn't narrow it down to the items I'm looking for. Is Digikey still the same place you order from? I did a search for Discrete LED Indication and there are over 16000 items listed and I'm not sure how to narrow down my search.

Can you give me some basic criteria that would help me narrow down my search to something more manageable?

Thanks a lot and happy holidays!
Tommy

[heyok]

I know what you mean, you really have to drill into it to find what you want.

Generally, I do a search for 3mm LED (or 5mm LED) and then you get a huge result. Scroll over to the right hand most (I think) column where it says Mounting Type and choose Through Hole. Maybe choose your colour from its column too. Search again and I think you will have a reasonable amount of things to look over.

Merry Christmas!
Al

[greenjk]

A quick question for you Al, I hope you can help me out, I just bought one of your controlers (Brake, Reverse and Driving Light Controller
Part No. BKFWRV) and need to now buy some resistors so I can run the lights on my wraith, 3s battery with 5mm leds and an rc bros light bar, can you tell me what resistors I will need.

[heyok]

Originally Posted by greenjk

A quick question for you Al, I hope you can help me out, I just bought one of your controlers (Brake, Reverse and Driving Light Controller
Part No. BKFWRV) and need to now buy some resistors so I can run the lights on my wraith, 3s battery with 5mm leds and an rc bros light bar, can you tell me what resistors I will need.

The BKFWRV sends receiver voltage to the LEDs so that is usually 6 volts.
It depends on the specs of your LEDs, but generally, 150 ohm resistors will do the job. Use 1/8 watt or larger. 220 ohm would be okay too, just not as bright.

For your RC Bros Light Bar, you would need to check with them... I suspect that the resistors would be built in. Send me a link to the part and I will try and find out.

[wingnutcrawler]

hey heyok, i have a question regarding running led's with no resistors. ive done it in the past with good results and ocassionally will have one fail but not too often. the leds i have are 3 volts. what i have been doing is wiring 2 of them in series figuring it could handle 6 volts from my bec. then i just parallel all the sets and it seems to work. what would the benefit of resistors be in my case. thanks in advance for any help u can give. carl

[heyok]

Originally Posted by wingnutcrawler

hey heyok, i have a question regarding running led's with no resistors. ive done it in the past with good results and ocassionally will have one fail but not too often. the leds i have are 3 volts. what i have been doing is wiring 2 of them in series figuring it could handle 6 volts from my bec. then i just parallel all the sets and it seems to work. what would the benefit of resistors be in my case. thanks in advance for any help u can give. carl

I think I covered it earlier, but basically, if you use a resistor you will ensure you are sending a known amount of current through the LEDs and therefore you can count on how bright they will be. Some of the LEDs might have a slightly higher or lower forward voltage so one string might be more or less brightly lit than the others.

[greenjk]

Originally Posted by heyok

The BKFWRV sends receiver voltage to the LEDs so that is usually 6 volts.
It depends on the specs of your LEDs, but generally, 150 ohm resistors will do the job. Use 1/8 watt or larger. 220 ohm would be okay too, just not as bright.

For your RC Bros Light Bar, you would need to check with them... I suspect that the resistors would be built in. Send me a link to the part and I will try and find out.

Thanks mate, big help.

[Brake Weight]

I got a bundle of 50 off of fleabay. They're already resistored for a 12v system, but I'm wanting them independent of my RC. So I'm looking to use a pair of 9v batteries in series along with a few 1/2w 440k resistors. I should be able to mount the 9v batteries under the bed of my crawler and tuck the wiring up against/into the body. This way, when I remove the body the lights go with it.



The online calculators made this a breeze to figure out. Now just to see how long a pair of 9v batteries at 18v will stay charged while dissipating 6v of energy.



By wiring the most of the LEDs in series and a few in parallel, I should be able do away with the 440k resistors...

[Kel]

Thumbs up for Heyok's lighting!

[heyok]

Originally Posted by Brake Weight

I got a bundle of 50 off of fleabay. They're already resistored for a 12v system, but I'm wanting them independent of my RC. So I'm looking to use a pair of 9v batteries in series along with a few 1/2w 440k resistors. I should be able to mount the 9v batteries under the bed of my crawler and tuck the wiring up against/into the body. This way, when I remove the body the lights go with it.



The online calculators made this a breeze to figure out. Now just to see how long a pair of 9v batteries at 18v will stay charged while dissipating 6v of energy.



By wiring the most of the LEDs in series and a few in parallel, I should be able do away with the 440k resistors...

I hear what you are saying about the convenience of not having to unplug something when you pull the body off. My preference would be to use just the one pack to power both the rig and lighting. I'm okay with another plug. Also, I really don't like using 9V batteries for anything because of their low capacity. If it works for you, go for it!

Originally Posted by Kel

Thumbs up for Heyok's lighting!

Thank you!