How to make many 12V or 5v LEDs light up from car power supply?

I want to build  some LEDs into my cars rear stop lights. They are round and they have holes where something like 20 LEDs could easily fit into one fixture. If I where to run something like 40+ LEDs off of my cars number plate light wiring how will I do it and what will I need ? I want to make this project as soon as possible and I promise to post pictures. I just need a simple and cheap way to do this.

gracedan3 years ago
I used the led strip lights (12V DC), and here's the step-by-step image for your reference.
There exist LED module replacements for brake light and tail light (and probably turn signal lights too).  For these, neither wiring, nor soldering, nor resistors,  nor electrical engineering, is required.  You just buy the replacement module for your car, and (if you got the right one) it comes with the exact same bulb-base shape, so you can just plug it into where the old one went.

This Google(r) image search,
returns a bunch of pictures of what these modules look like.

If you really want to roll your own, that will probably take more time and too much effort, but I dunno, maybe it would be worthwhile if you could make it spell your name, or some other cutesy, unsolicited, message for the drivers behind you.  I think at least one of these pictures,
had an example of that.

BTW, in the former US,  where I am from, these are called "brake lights",  I mean referring to the red lights on the back of a car which turn on when the car's brake pedal is depressed.

In contrast, "stop lights", same thing as "traffic lights", are those great big lights, red, yellow, and green, bolted on towers to the edges of the streets, big enough to be seen from blocks away,  the ones that signal to all the cars when to stop and when to go.

Uh... that being said, you'll get  more relevant search results using the phrase "brake light", rather than "stop light"
Google for an LED Calc. There you will be asked to give the source voltage, the LED's forward voltage and current, and it will ask for how many LEDS you want to use. It will then generate a schematic for you and tell you what resistors you will need for the circuit to work.