Light fixture upgrade continued :
Now that I've figured out what leds I'll be placing in the fixture, time to remove the old florescent light's wiring.
It's held in place by pop rivets.
Drill out the center of the rivet.
After a few of these, this is what your drill bit looks like.
With the florescent wiring gone I noticed the extra space within the light fixture. It got me to thinking and I decide to use that extra space to add some more leds.
Since I already had white light I thought I'd add some "Das Boot" lights. These will be like the red lights you see in just about every submarine movie that's not in black and white. They are so the crew can go from inside the sub to the outside without having their night vision ruined. Should work the same way for me when camping.
I'll be using a different type of led than the white ones I used before. Here is what they look like. It's a high powered "star type" led.
Since these leds are high power I'll only be using two of the red ones while I used 114 of the white leds.
One of these red leds will use 350 milliamps while a single white led only needs 20 milliamps. 1 amp = 1000 milliamps Along with extra light the led produces extra heat. So much extra heat that a separate heat sink is required. The data sheet reads that they are not to be run longer than 5 seconds without one.
The star board under the led, beside providing pads for soldering on wires, gives an attachment point for a heat sink.
I'll use silicone to mount the star boards onto the metal of the light fixture. It's more than large enough to act as a heat sink and safely dissipate the excess heat.
There's another consideration with high power leds. The voltage supplied by the van can vary by several volts. On the lower powered white leds it's not a problem. You can run them with just a resistor wired in series to limit the current so they don't burn out. For the high powered leds it's another matter. The led you see in the above picture and another one just like it I managed to burn out while doing this upgrade.
To safely power the red leds I'm using a small circuit board called a "constant current regulated led driver". This will keep a constant current flowing to the leds even if the input voltage changes.
Here's what a couple of the led regulator circuit boards look like.
The regulator board arrives with these metal pins used for plugging them into a light fixture.
Use a soldering iron to remove the pins and replace them with wires.
This regulator board will work with both AC and DC. Since it's being used for DC I could increase it's energy efficiency a small amount by bypassing these four diodes.
For size comparison that's a toothpick below them. I 'm not that good with a soldering iron so it will remain unchanged.
I need a way to secure the regulator board to the light fixture. Use a scrap piece of left over acrylic and cut out three small blocks then glue the two small ones onto the larger one.
The regulator board has small tabs on each side.
Use a hacksaw to cut grooves on each side of the acrylic holder to match those tabs.
Add some silicone then slide the board into place.
Clean off the metal surface of the light fixture along with the back of the led stars with alcohol.
Silicone everything into place then let it set up.
Wire the red leds to a small switch and mount through the side of the fixture opposite from the original power switch.
Test it out.
The red leds draw 0.16 amps. The photoresistor gives a read of 4.8 without the diffuser and 6.8 with it. So the red lights aren't as bright as the white leds or the original florescent light but they are still plenty bright and use a little more than a 1/10 as much power.
Next attach the white leds by putting dabs of silicone onto the back of the plastic trays that hold the led boards.
Put the led boards into the trays and secure them to the fixture.
The led boards would slide back in forth in the trays so secure in place with some more silicone. Let it all set overnight.
Wire it all together. The white leds are wired to the original switch for the florescent light. The two sets of leds light independent of each other.
Install back into the van.
My visibly bored supervisor for this project.
List of parts.
DealExtreme
12V 75-LED White Light Strip - $10.28 Used 1 and 1/2 of these.
300~350mA Constant Current Regulated LED Driver (12~16V Input) - $2.25
Mouser
Z Power LED, P4 Series, Red - 2 x $3.88
The small switch I had on hand. The 2 leds I burned out were from DealExtreme so they were cheaper than the Mouser ones.
I have a question. To hold the light fixture on edge I used a couple of these.
It's a rectangular steel "brick" that has "SUP-R-DIE" written on the side. I found them among my Dad's tools. Dad was a Tool and Die Maker. They're kind of handy. Any one know what they were specifically used for?