I recently traded in my big pickup for a blazer. the big truck had a full size light bar on the roof but the blazer has a sunroof so I cant go that way again. I looked at different hideaway strobes and I even have an old twin tube strobe dashboard plow light but where's the fun in using something off the shelf.
I was at a yard sale and saw these "hi Intensity" fog lights for $5. Hmm it didn't say halogen and the lenses are plastic but on the bright side :( the housing is metal as are the mounts so why not grab em.
These will work great on my blazer and I even may make a single LED set for my snow-blower. Hopefully this will be a mild winter but I'll be prepared....
Step 1: Disassembly Time
First thing was to disassemble them. The lenses are just clipped on. I removed the lamps and the contact and spring too. The socket itself was riveted to the bottom of the housing but a step drill quickly released that....
Step 2: Led's and Heatsinks
I had some 10 Watt LED chips. They work fine in a car with just a 2.7 ohm series resistor. You can go with a constant current driver but in this instance they don't stay on 100% so I don't worry. its usually a 50-50 duty cycle when they are in use. I decided on 3 Leds per light. I cut a piece of 1/8 aluminum plate to match the contour of the housing. I used a delta band saw but even a hacksaw will work.
I laid out the three leds centered across the middle of the plate. I tried to get them centered behind the different sections of flutes across the middle of the lens. A little heat sink grease under each one helps to keep them cool. Some 6-32 hardware keeps them in place.
Step 3: Wires and Grommets
I used some 16Ga wire since each chip draws about 1amp and that's 3 amps per light fixture. I put a grommet in the hole in the bottom since the original wire didn't have one.
To feed the power wire to the resistors I drilled a 1/4 inch hole in the heat sink plate and put a small grommet in that hole to protect the power lead.
Step 4: Wiring and Epoxy
After wiring the leds in parallel I grounded the negative side to the heat sink and used some epoxy to hold the resistors to the heat sink. This keeps them cool and help to reduce the chance of stress cracks in the leads. I attached the black lead to the back of the plate using the same screw that grounded the from side.
The hardware I had was 1 inch long. I got a great deal on the hardware at 10 lbs for $4 I sometimes take a Dremel and chop them flush when I'm done. I didn't do that this time since its hidden in the reflector. I used two more screws, one at each side, to pin the plate to the reflector.
Step 5: Putting It All Back Together
I put the rubber gaskets back where they belong and snapped the lenses back into place.
After a quick test and I put them back into the box until it stops raining outside.
The movie shows them hooked to one of my other instructables... the generic light controller. it doesn't seem to play right unless I download it to my desktop. Maybe its just me. I programed 4 flash patterns and it shows each one for a couple of seconds
I'll add some pictures of the truck when I finally get them mounted. Thanks for looking!