When I was upgrading all the lighting in my house to LED lights (My adventures in LED home lighting) my favorite Ebay LED bulb seller often had some other LED type items on sale. I occasionally put in some lowball bids and wound up with some items for stupid cheap prices (anybody need any LED street lights?).
One of the items that I bid on and won was an LED desk light… 5 bucks or so and shipping costs were combined with some other stuff I bought that day. It was advertised as a 10 watt light, but was actually a 4.8 watt light. It used a Chinese 4x3 5000K LED array driven by an unregulated wall wart supply. The light quality was OK, but the CRI was probably around 70. It put out around 250 lumens.
Then Old Lumens got me hooked on those damn Nichia 219 4500K, 92CRI LEDs from Illumination Supply. So what’s a boy to do? Out with the old:
And in with the new (triple LED 20 mm star):
Add a tiny little driver:
And prestakazoo!:
I changed the wall wart to a 12V one. The driver puts out around 8 watts (9.5V, 0.8A). The fixture now puts out around 550 lumens. Without the reflector it only does around 350 lumens… this is the only light that I have that actually puts out more light with a reflector (due to the black head of the lamp soaking up light like a sponge). I left out the old lens. The LEDs were pretty close to the edge of the lens, plus with it open it gets better airflow. The head runs around 55C.
The driver that I used can do 1.2 amps. I could mod the sense resistor and get more light. The driver also supports dimming via PWM, a variable voltage, or a variable resistor (aka a pot). I am going to replace the power switch with a pot, but need to fab a bushing. The hole for the switch is too big for the shaft of the pot and it can’t be secured in the existing hole.