I don’t really know if I need it to do this modification on my car… the 5w lamp was ok, but my 5 led circuit its more than ok, so don’t start this project unless you really need it or like it because your ceiling lamp is just fine as it is. Here is the schematic of the circuit, I’m not going to attach the board to because it’s a pretty simple circuit diagram so I didn’t design it with eagle; I did it by hand.

5 LED’s for car battery 12v schematic

click on pic to enlarge

As you can see its composed of 5 white led’s, 5 resistor’s for current limiting a capacitor for a nice smooth turning off effect and a diode that doesn’t allow current to flow back to the car from the capacitor. The capacitor can be removed if you don’t like the smooth turning off effect or you can adjust its value to obtain the desired effect. I used 6900 uF and I have about 3 seconds of light after I switch off.

From the next picture you can see that I used 3 x 5mm LED’s and 2 x 10mm LED’s, that’s only because of what I had available.

5 LED’s for car battery 12v

click on pic to enlarge

You can use whatever dimension and color you like. From the picture you will also notice that I attached the capacitor with wires so that I can place it in a space behind the circuit (because the capacitor is large I don’t have room for it on the board). About the resistor’s I used they are 680 ohms and were calculated to fit my LED’s. It will probably work well for any LED I suggest not to use smaller then 680 ohms resistor, because you will burn your LED’s. If you would like to recalculate your resistor value based on your LED’s and voltage you can use this application http://led.linear1.org/1led.wiz . You will have to take in consideration that your car’s voltage may vary from 12 v to 14,4 v so make sure you cover this variation.

On the next picture you can see the 5W lamp socket. I’m going to connect my circuit to the lamp’s socket connector. In my car you can see that the casing its all plastic so it wont be a problem of isolation. But if in your car you place the circuit near metal parts you have to make sure that none of the board is actually touching the metal.

daewoo matiz ceiling lamp

After doing that you can place de cap back over the new circuit with LED’s and its ready to go.