Hi everyone,
I have some LED Christmas Lights here with those functions boxes that change the way the leds blink/fade. I would like to control the sections through an Arduino. So, I disassembled the function box and measured the voltage with a multimeter to find out how much energy I would have to use to turn them on.
Turns out that the output is about 190V DC (input is 220V AC). How can I get this voltage from another source and be able to control it?
Thanks
The OUTPUT is 190VDC? For a LED string? Wow. Ok, well one choice there would be to use a relay, have the Arduino control the relay turning it on or off. Personally, I can't think of any other way, but someone here is bound to suggest something else.
Yeah, I also think it is very strange. It is a 100 led string (it seems to be divided in 2 sections). The problem is, I can't use the power from the function box as it changes the function from time to time, so I would need to get the power elsewhere (I could also change the function to steady lights each time I turn them on :P).
Ok, so you want a constant, clean power to the LED strings, and not the (programmatically) controlled power from the box. You'll need to build yourself a regulator to take the 220VAC to 190VDC then ... Actually, you should be able to pull power off of the regulator that's in the control box, before it gets manipulated by whatever controller IC that'ss in it. I guess with two strings, 50 LEDs each, 190VDC comes out to 3.8VDC per LED. I guess they're all in series then.
Can you run the lights on 110/120VAC? Normal house current?
@GoForSmoke the problem is that the here we have 220V AC 
And even at 110AC, wouldn't the LEDs just light up when the current is flowing in the right direction?
@KirAsh4 Yes! Thanks for the tip. I figured out where to get the power from the circuit board before it gets controlled by the IC. I guess I'll have to use them to power the LEDs and find a transistor good enough to handle such high voltage (or maybe a relay, but I would prefer a transistor) to control the strings from the Arduino.
My guess is, that IC isn't just controlling the turning on/off of the voltage, but also current through the string. Can you get a part number off of it? Can you see resistors anywhere?
I was looking to see if the brightness fell.
Allelectronics sells, for example, LEDs with built-in resistors for 12V operation. That allows a 12V supply to run many with no worry about if one or more fail and no time spent soldering a whole pile of resistors. But they run about 50 cents US each unless you buy in real quantity.
Given that I can see that mass production would have the resistors built in and that does lead in interesting directions if the suckers can be gotten pre-wired relatively cheap, say on a string of tree lights.