LED Fog Light

So my brother got these dark taillights for his BMW car. Unfortunately the bulb for the fog light is missing. Actually it isn’t possible to install a bulb as it’s not prepared for it.
Now I needed to solve this somehow. And as I’ve been meaning to look into LED lighting for some time I used this as an excuse to make one.

First here is the schematic:
led-fog-light

So how’s it work? Easy. The current for the LEDs is controlled by Q1. Q2 works as an overcurrent switch and controls Q1.
And the current itself is set by calculating R2 = 0.5V divided by the wanted current.

Here are some photos I made of the circuit. I know it’s a bit primitive, but it gets the job done.

fog_frontfog_backfog_control

Here is the list of items I’ve used:
LED1-LED5 = Red 5mm 17000mcd power LED
R1 = 100K
R2 = 5R (0.5/100mA)
Q1 = IRFZ24NPbF
Q2 = BC547B

I got my LEDs at dioder-online.dk. You will probably be able to find a shop dealing LEDs near you too.
And although I would love to have come up with the circuit on my own, I’ll admit to have found it on the Internet at instructables.com.