# Noob tryin to get his head aroung combination circuits and powering them

Joined Jun 28, 2017
1
I am building a luminary out of Samsung rigid LED strips. (Bridgelux EB series BXEB-L0560Z-40E2000-C-A3)
Problems I am facing:

1. Constant Voltage power supplies are cheaper than Constant Current, budget is important
2. I would like to put a dimmer on this but dont know the best way to do it.
3. If I go with CV, I need to connect the strips in parallel
http://imgur.com/JlLaXfa
So my selection here is pretty straight forward, 24 volts, 1400mA = 33.6 watts per strip. Since the voltage is constant adding the current results in 5600mA , I can select a simple 24 volt CV supply rated for 6+ amps or 134+ watts, (I think)

4. However if I lay my circuit out like so, with two sets of 4 strips, the 4 strips in parallel, but the two sets in series...
http://imgur.com/MTJdWbD

What does that do to my power requirements? I could do two separate power supplies, but thought this more economical. I was thinking a 48 volt 300 watt supply, across the series would present the required 24 volts at the top of each parallel set of 4 strips. The strips still get their required voltage (series divides voltage across the loads) but I am unsure how this would affect the current.
Beyond that, could I dim each array separately or would I be stuck with one dimmer or is dimming impossible?

I could just cough up the $150 for a Mean Well HLG 320 constant current with built in dimming, but it is killing my budget. Trying to keep this under$200 and the strips cost $120 so I have a$60 driver budget and \$20 for misc.

I am super rusty on all this, its been like 20 years since I took analog/digital electronics.

#### wayneh

Joined Sep 9, 2010
17,493
You can't drive those with a constant voltage, and you can't put them in parallel without protecting each strip individually. They are not internally current-limited. Your current limiting could be as simple as a series resistor, but that will require a resistor with an adequate power rating and the resistor will burn off excess power as heat. A constant-current drive would likely be more efficient, but of course does have a cost.