# Leds and arduino

Hello people , can anyone help. I connected 200 led diodes in parallel ( led spec: 3.2v , 20mA) and I use 12v power supply. On power supply I conected dc-dc converter and lowered voltage to 2.9v. I checked every diode and each works at 2.9v. The diodes are turned on and off by an arduino uno and mosfet.
My question is : will the diodes work as if i connected to 12v via a resistor. The diodes are high quality, I know it shouldn't be connected that way. But I'm just wondering if it will blow out after a while or it will work like with resistor. Thanks in advance to everyone.

200 x .02A = 4A Lot of current. Each one has it's own current limit resistor, yes?

Since all are being turned on at once, being connected in parallel, I would have suggested connecting as strings of 3 in series with a current limit resistor.
(12V - 3.2V - 3.2V - 3.2V)/.02A = 120 ohm resistor P=IIR, .02*.02*120 = 48mW, so common 1/4 W resistors will do. Small 1/8W will do also.

200/3 = 67 strings (one with just 2 LEDs, do the same math as above).

Cuts current down to 1.34A, makes life easier for the MOSFET as well.

Running at lower voltage may work long term, what you have set up tho is a bit of a science experiment.

none, the led diode has no resistor , they are all conected in parallel and conected to 2.9v dc-dc . 200 led draw 2.85A current