Howdy! I took apart a multicolor smart light that had a bad power connector. One of the salvaged parts is the 35V LED panel with R, G, B and 2 white components (5 colors total). Thru trial and error, I can see that has dim light at 12v and gets brighter up til what it's rated for. Here are my questions:
Given its high voltage rating, is this something I can control with an Arduino at all? I saw an ESP8266 in the smart bulb, and after poking around I was clueless on how it actually controlled the colors. Obviously the pins can't output that, nor handle it coming back to ground. I have step up and step down voltage converters, but it seems like a bad idea to do one on either side of it.
If so, should I control the color component brightness through PWM? Of course, I can control each color individually with 5 relays (total), but that seems excessive, and PWM doesn't seem practical (or quiet) with PWM. I imagine I could use transistors, but I have no experience with those and don't know where to start.
LEDs are normally "current controlled". This is because LEDs are non-linear (like all diodes). Their resistance drops drastically as voltage increases and current can run out-of-control.
So you supply a known-fixed current and the voltage "falls int place". This is the opposite of how most things work... Usually we supply a fixed-known voltage and the current "falls into place".
With regular little LEDs we control/limit current with a series resistor, but with high-power LEDs that's not practical because the resistor wastes about as much energy as the LED (and if you're going to do it, you need a high-power resistor).
High power LEDs normally use a switch-mode constant-current supply. (Or controlled-current for dimming.) That's not an easy thing to build yourself.
There are PWM-controlled constant-current LED power supplies but normally the PWM is just a control for the power supply and it doesn't go-through to the LED. The slightly-unfortunate thing is, the industry standard is 10V PWM (or 0-10VDC).
All switchmode power supplies (both constant voltage and constant current) use a kind of PWM internally but the actual output is normally constant DC.)
If it contains an ESP8266, you are on a roll! This means that you can (re-)program it yourself. It is always the case, that the most useful approach is to use the circuit as-is.
It controls the colours by PWM. There will be FETs for each colour to switch the 35 V. How do you know it is 35 V?
Your mission - should you choose to accept it - is to fully trace out the circuit and understand how it works. Anything else is just a waste of time and materials.
@jremington Thanks, I appreciate it. The link seems to be broken, unless I'm not understanding what you're sending.
@DVDdoug This is great information for me, thank you! I'll look into this.
@Paul_B I unfortunately am a fool and disassembled the board and all the components all together lol. I kept the little ESP8266 chip thought haha! I found out that the LEDs were 35V was because I found something that said "35V" under a coil near the LEDs, and so I just guessed haha. Plus, it doesn't light for anything under 12V. I'll try doing my best with the info here cuz I'd love to learn.
