How to wire LEDs

[PileDriver]

Yes this is true the nominal volts is 7.4 while charged up is 8.4, I am pretty sure when you set your bec to 7.4 that's what the receiver will put out and not the 8.4 volts.

Thanks for the help and sorry for asking questions that were already answered here. I was reading this on the fly at work. Thanks again!


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[heyok]

Welcome!

[PileDriver]

One other question is why does each led need a resistor? instead can't u just wire up the leds in parallel with one resistor? Thanks.


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[HahnsB2]

Originally Posted by PileDriver

One other question is why does each led need a resistor? instead can't u just wire up the leds in parallel with one resistor? Thanks.


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You will need a higher wattage resistor depending on the amount of LEDs, not quite as readily available. Also if you happen to have LEDs of different forward voltages (such as using a blue LED in a rear U4 style light bar) I believe that would also cause a problem.

[heyok]

Right.
Different colour LEDs have a different forward voltage. For example, some red ones are 1.7 volts. Put that in parallel with a blue or white (which are often about 3 volts), and the blue or white won't light up. The red will have clamped the voltage to 1.7 volts.

[PileDriver]

How about if I wire up 10 whites do I NEED 10 resistors?


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[heyok]

Yes

[PSH72]

Heyok can you tell me if I need to waterproof the leds?

And how can I waterproof the resistors could I use silicon on leds and resistors?

[heyok]

Yes, you can use silicone. I don't bother with it... actually, I guess I do. Usually I coat the connection with Plasti Dip. Probably just covering with heat shrink is enough, but if you like to turn your rig into a submarine, then doing more to waterproof the connections really can't hurt.

Clean water won't hurt anything though. It might lead to corrosion, but the lights will still light up if the connection is wet because we are dealing with such a low voltage.

[PSH72]

Originally Posted by heyok

Yes, you can use silicone. I don't bother with it... actually, I guess I do. Usually I coat the connection with Plasti Dip. Probably just covering with heat shrink is enough, but if you like to turn your rig into a submarine, then doing more to waterproof the connections really can't hurt.

Clean water won't hurt anything though. It might lead to corrosion, but the lights will still light up if the connection is wet because we are dealing with such a low voltage.

no , no submarine here, its a crawler just to have some fun, and since I will drive in winter thats arrived here in Portugal, there will be some pudles of water and I just didnt want to burn any led or resistir, but if there is no problem I will live it as it is, becauses mayby the silicon in the summer could harm the resistor on hot days...

Thanks for always been here for the help

[PileDriver]

Here are four red leds I wired up in a light bar as a brake light for the back of my wraith.


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[heyok]

Just a note that I have fixed the images in the tutorial that Photobucket had chosen to hide.
Hope this is still a helpful guide.

Al

[StomperCrawler]

Originally Posted by heyok

Just a note that I have fixed the images in the tutorial that Photobucket had chosen to hide.
Hope this is still a helpful guide.

Al

Thanks for that!

[heyok]

Originally Posted by StomperCrawler

Thanks for that!

You're welcome.

[GrimmTheTourist]

I ordered leds and resistors yesterday because I want to do it myself and I prefer warm white for head lights.
And now I found this.

Thanks a lot. Great tutorial!

[heyok]

Originally Posted by GrimmTheTourist

I ordered leds and resistors yesterday because I want to do it myself and I prefer warm white for head lights.
And now I found this.

Thanks a lot. Great tutorial!

Thank you for the kind words!
Please post up a picture of your lights to help show others what you are able to make.

[flyingwil]

Thanks for fixing the pictures Al!

[GrimmTheTourist]

Originally Posted by heyok

Thank you for the kind words!
Please post up a picture of your lights to help show others what you are able to make.

I finally had time to do some soldering. 4x 3mm warm white in the front, 5x 5mm cold white on the roof and 2x 3 mm red in the back. All soldered to one connector. I have a switch for the roof lights and hide it in a box.

The rear lights are a bit too bright for my taste. Looks like I am on the breaks the whole time. Can I just add one more resistor to reduce the brightness?
I use 150 ohm resistors in the front and 470 in the back. 6 V from reciever and the leds run with 3.2 V @ 20 mA. (8'000 to 18'000 mcd, 20°)

[heyok]

Nice looking rig! Congrats on your wiring.

The rear lights are a bit too bright for my taste. Looks like I am on the breaks the whole time. Can I just add one more resistor to reduce the brightness?

I find that about 1K ohm to the rear LEDs seems bright enough.

[Hydrocarbon92]

Yes, the resistor will drop voltage. You'll have to play with values since our eyes don't perceive light decrease linearly. 1/2 the light output only seems 20% dimmer.