Modifying 120vac LED string lights to run on 10 volts AC or DC

aussteve

New elf
Joined
Aug 30, 2016
Messages
3
Location
USA
I have some LED light strings (Walmart brand) that have 60 LEDs (3 strings of 20 each) which are controlled by a 16 function MFC. They are designed to run off of household 120vac. I would like to run them off of a 8-20vac input or e a 5v -12v DC input instead of the 120vac the circuit is designed for.
Here are some pictures of the controller circuit board

Frontside http://s86.photobucket.com/user/aussteve/media/IMG_20160829_160159715-a-25-60_zpsmgoc4ehj.png.html?sort=3&o=0

Backside http://s86.photobucket.com/user/aussteve/media/IMG_20160829_160436592-a-25-60_zpsxu55sths.png.html?sort=3&o=1

Schematic http://s86.photobucket.com/user/aussteve/media/IMG_20160829_162409823_zps4ygf0wfo.jpg.html?sort=3&o=2


Any ideas on what I can modify in the circuit to lower the input voltage and still get the circuit to function
as it does on the 120vac source?
 

aussteve

New elf
Joined
Aug 30, 2016
Messages
3
Location
USA
My main focus was to try and make use of that 16 function controller which I assume is on the vertical pcb (that is soldered into the main board). I would like to run 8 - 10 leds off of each output which currently runs 20 leds each. I can supply the 8 - 18 vac or I would prefer to supply a clean regulated 5.0 vdc to the board. I just can't figure out how to get this board to work and use the 16 lighting functions at a lower voltage. I was hoping someone had done this before or could give me some hints at things to try.
 

David_AVD

Grandpa Elf
Community project designer
Generous elf
Joined
Jun 12, 2010
Messages
4,681
Location
Victoria Point (Brisbane)
The board needs to see the AC (currently via the 2.7M resistor) to do the timing for the phase control.

I guess you could try changing R1 to around 2.2K and R2 to 220K and see how that goes.

For 8 LEDs, you'd need about 20VAC while 10 LEDs would require about 24VAC.

Each LED string will also need a current limiting resistor; maybe 470 Ohms at a pure guess?

You could start higher on that and decrease the value for increase the brightness.
 
This thread is very old. An answer might not be needed anymore.
Top