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Topic: 4x3 LED array not bright enough (Read 248 times) previous topic - next topic

blind_squid

I've been trying to build a 4 x 3 LED array using the following parts:


The LEDs are mounted on a heat sink and wired in a 4x3 array (3 chains of 4 LEDs wired in parallel).

A schematic of the circuit can be found here: LED circuit schematic

I'm using PWM to control the brightness of the LEDs through pin 11 (not pin 13 as the circuit illustrates).

The circuit works; however, I'm certain the LEDs can be brighter, and for my application, they need to be brighter. Can anyone give me any advice as to how to modify this circuit in order to increase the brightness of the LEDs?

PaulRB

#1
Dec 04, 2015, 12:09 am Last Edit: Dec 04, 2015, 12:17 am by PaulRB
Hi, i supect you need 4 of those "buckpucks", not just one. Right now, the 700mA is split 3 ways because of the 3 sets of leds in parallel. And there's no guarantee that split will be equal. Each set of leds is only receiving a third of its max current. One "buckpuck" per set of leds would give the full 700mA to each set of leds.

Each group of 4 leds in series will require a supply voltage of at least 15V. You are only supplying 12V, so you can only have 3 leds in series. Suggest you make your array as 4 sets of 3, with a buckpuck for each set and use a 3A power supply.

Paul

blind_squid


PaulRB

Would this 4-channel LED shield work in place of four buckpucks?
Looks like it might be suitable... Wierdly, there is one review on the site which says "DO NOT BUY IT" and then gives it 5 stars!

blind_squid

I contacted the seller and got a response in a matter of hours, so I'm confident that any issues that may arise due to lack of documentation will be resolved promptly. As for a power supply, I think I'll upgrade to this one:

http://www.amazon.com/gp/product/B003WJ218U?psc=1&redirect=true&ref_=ox_sc_act_title_1&smid=A325274ZEF9XYZ

assuming four strings of 3 LEDs, which will be controlled by the four channels of the LED shield.

Thanks for your help!

jackie16201

@blind_squid, Did the LED shield and different power supply end up solving your problem? I am facing a similar issue.

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