Good points.
Yesterday evening, while watching that improbable(!) UCONN comeback and victory over Duke, I pulled apart one each of the 3-panel 3000 lumens versions and one of the 4-panel 4000 lumens folding “cheapo” LED lights from Menards. The 4-panel unit has a short base which precludes it from fitting into some light sockets. Otherwise, the 3-panel units appear to have no real advantage except for lower power consumption and the panels running at a slightly lower voltage because the manufacturers cheaped out on the capacitor in the main housing. They may thusly run slightly cooler than they otherwise would. They all run quite hot, and reliability can’t be very good.
In all models, the panels each are rated at ~1000 lumens of 5000k light. Heat sinking is non-existent: The fake heat sinks are plastic, and serve only to help retain the LED circuit board. The LED boards as usual have a thin aluminum layer on their backside. There is enough wire to be able to cut wires and make new connections and insulate them readily. No need to solder to the “fragile” circuit board.
The internal details vary slightly, and not very significantly. Since I am after small cheap LED panels to “scavenge”, the 4-panel light looks like the best bet, as it is on sale for the lowest price. Maybe they cook themselves the fastest and Menards is trying to dump them?
At any rate, the base of the 4-panel light contains a small PCB (printed circuit board) with only 3 components: A full wave bridge rectifier, a small electrolytic 200v capacitor, and a small resistor that serves to slowly discharge the capacitor when the light is turned off. The 4x board outputs to the panels are in parallel and run at ~160 volts DC, with over 10 volts of AC ripple. The entire light is rated at 40 watts, so, each panel should draw 10 watts — easily believable considering how hot they get. Each panel has 2 IC + resistor circuits each running 7 LEDs.
Theoretically then, each panel is drawing ~0.0625 Amps (62.5 mA).
As I want to “create”, essentially, sets of independently switched LED panels as simply as possible - that is, not needing a wall wart supply, these should work out great:
A simple single diode & capacitor, plus a “bleed resistor” in a 60 cent switch (or outlet) box will suffice to provide the DC for a panel. Add a switch, cover plate, and wire - even decent quality 18 ga. lamp cord will do. A heat sink for the back of the LED module is a given. :-)
Since this operates at high voltage, over 150 volts DC, I will use the same precautions I would for a 120v AC circuit, or a bit more. (It’s really no more dangerous than a 120v AC light, hand tool, kitchen gadget, etc.)
I can adjust how hot the LED panel runs by adjusting the capacitor value:
but I also have to check the ripple voltage rating of the capacitor. An inline resistor can also do the trick.
Fun stuff!