I was about to place a small order from All Electronics, a great miscellaneous parts and surplus electronics shop, when I checked the front page to see if there was anything new to consider. And that’s where I saw a familiar-looking LED worklight lamp head.
I recognized these as from Dewalt DCL040 LED flashlights ($49 via Amazon).
Here’s their product description:
This good looking fixture is a great beginning for a shelf or display lighting project. Bright, white 1 Watt LED enclosed in a rugged black and yellow hard plastic housing with a conical reflector and a clear plastic front lens. Overall dimensions, 2.16″ diameter x 3.45″ long. Two 4″ wire leads. Operates on 3 Vdc @ 300 mA. For higher voltages use a dropping resistor (see image to left).
The price is $2.50 each, or $2.25 each if you buy 10 or more.
Buy Now(via All Electronics)
These are powered off of 3V (I tested one – it works), and you can use a higher voltage source if you choose an appropriate resistor. There’s a handy chart on the All Electronics website if you’re not familiar with powering LEDs and don’t want to head to Google for answers.
If I wanted to use a 5V power supply, I’d need a 6.67 Ohm resistance. I’d have an easier chance looking for a standard-valued 6.8 Ohm resistor. The power dissipated across the resistor will be 2V x 0.3A = 0.6W, so I’d need a 1W resistor. Or 3/4W, but I assume there’s greater selection of 1W resistors.
(I say I and not you because I’m just thinking aloud here. You’re on your own in determining a safe and reliable way to power these LED modules. I have only tested these lights at 3V, and briefly at that. I’ve got more work to do. Use any of this at your own risk.)
If I wanted to use a 6V power supply, I’d need a 10 Ohm resistance or slightly greater. Again, I’d need a 1W resistor. Maybe 12 Ohms?
1W resistors are fairly easy to find. A quick search on Mouser turned up a couple of options. 6.8 Ohm with 1W power rating and 5% tolerance sells for as low as 10 cents each, individually.
This one, from TE, is 3.1 cents each if you buy 100.
Maybe Amazon, Ebay, or a straight-from-China marketplace would be a good place to look for just a couple resistors. There’s also this Joe Knows Electronics 1W resistor kit for $35, but that’s overkill. I ordinarily use 1/4W or 1/2W resistors and would be hesitant to buy a 1W assortment for myself.
I order from Mouser regularly and will likely spend $10 on a few 1W resistors with my next order.
There are higher rated resistors too, obviously at higher cost.
But if using higher voltage supplies, maybe a voltage regulator is the way to go. Maybe I’d try for a 3.3V voltage regulator, perhaps with a small resistor to drop the voltage to 3V? A 0.3V drop at 0.3A would be what, 90 mW, so a 1/4W resistor would be more than enough.
Ben – your thoughts? How would you power these LEDs from a DC battery source?
I might dig up a fully assembled Dewalt LED flashlight and see what they use to drop the voltage from 20V Max (18V) to 3V.
I knew I wanted a couple, so what the heck, I ordered 10.
They’re a little dirty, with flecks of black (plastic?) stuck on, but they seem easy to clean. They feel a little greasy too. One wire has some fixturing epoxy stuck to it.
Anyone know what that white hot-glue-like fixturing stuff is called?
In other words, it seems that these were removed from assembled work lights. Some of the lenses are scratched a little, but aside from the slight amount of dirt, these look new.
So I’m going to assume they were removed from new equipment.
I’m not quite sure what I’ll do with 10 of them. Some will go to an LED worklight light bar project. Maybe I’ll swap the white LEDs in a few for RGB LEDs.
The output is quite center-concentrated. The deep reflector is a good one, but the output is a little harsh.
I definitely got my money’s worth, but I just have to now find a good way to use them.
At $2.50 each, who else is buying a few?
Oh, and if you do order one and take it apart, I’d appreciate any advice! The yellow housing screws together in one place, but I can’t see an easy way to remove the LED emitter, reflector, and lens assembly – the black part.
I wonder how and why these ended up at a surplus electronics parts store. Maybe something was off-spec. The LEDs? The housings? I doubt anyone at Dewalt will tell me, and All Electronics might not know.