# smd headlights/tail lights for rc car

#### luna_mick

Joined Aug 27, 2012
6
hi every one new to this so be nice I have a rc car to which I would like to make headlights and tail lights I already have an idea on how to make the fittings I would like to know how to wire smd leds using 6v dc supply and a small push switch if possible im quite handy at audio car installs I just not sure about leds especially smd . these are the type of smd id like to use or something similar any help would be appreciated thank for reading Michael

http://www.ebay.co.uk/itm/1-8-2-3-4...id=100033&rk=1&rkt=4&mehot=pp&sd=311209080438

#### luna_mick

Joined Aug 27, 2012
6
ok so do you know of any that will run to 6v as im not sure what im looking for .

#### Papabravo

Joined Feb 24, 2006
21,225
You should not be looking on eBay for LEDs. You should look at an electronics distributor for just the LED, then you can choose a resistor to match your voltage supply to the correct current. It works like this:
1. You find the LED you want to use and consult the datasheet for the forward voltage drop.
2. You subtract the forward voltage drop from your power supply voltage.
3. You divide the remaining voltage by the current required for the desired brightness. Then choose the closest 1% resistor value to the computed number.
Easy Peasy.

Example:
1. You find a white LED with a forward voltage drop of 3.2V @ 32 mA
2. You subtract 3.2V from the 6V of your power supply to get 2.8V
3. 2.8V/0.032 = 87.5, and 86.6 Ω appears to be the closest 1% value.
Now you take the 2.8 volts and divide it by 86.6 to the actual operating current of 32.33 mA. If you chose 88.7 Ω instead then your operating current would be a bit less, or 31.56 mA

http://www.brannonelectronics.com/images/STANDARD VALUE.pdf

See how easy it is when you know what you are doing?

#### TheButtonThief

Joined Feb 26, 2011
237
Do they have to be SMT LED's?

I made some headlights, rear lights and brake lights for my HPI nitro car. Put a micro switch behind the throttle servo so that when that swings back to kill throttle and pull the brake, it knocks the switch and brake lights come on =)

#### luna_mick

Joined Aug 27, 2012
6
whats the fun in buying kits ill never learn that way for future . and yes its easy when you know how lol . I might just take myself of to maplins and see what they have to offer as I haven't got a clue where to get leds from apart from ebay.

#### Papabravo

Joined Feb 24, 2006
21,225
whats the fun in buying kits ill never learn that way for future . and yes its easy when you know how lol . I might just take myself of to maplins and see what they have to offer as I haven't got a clue where to get leds from apart from ebay.
Where do you think people got components before eBay came along? Yup -- you guessed it, mail order distributors.

#### djsfantasi

Joined Apr 11, 2010
9,160
Where are you located? If in the US, look at Digikey or Mouser. If in the UK, you can also try Farnell or Rapidonline... Found these by Googling for "electronic supplier".