# I have limited understanding of circuit design and am thinking I need a constant current circuit to power 4x specialised LEDs in series/parallel

I have 2 strings of 4 LEDs connected in series and am thinking a constant current circuit due to the voltage drop and forward current requirements. Each LED has $$\V_f\$$ of 6.1v and requires $$\I_f\$$ of 350mA.

My thinking is to run each string in series and connect the 2 strings in parallel but am really unsure as to design. Can anyone assist with correct design or thinking on this please?

• There are off the shelf led drivers that can be got at low cost. No electronics skills needed. Problem solved. Commented Nov 9, 2022 at 5:25
• With what do you expect to power it? 24.4V 700mA? Commented Nov 9, 2022 at 5:26
• Please edit the question to limit it to a specific problem with enough detail to identify an adequate answer.
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Commented Nov 9, 2022 at 8:53

## 2 Answers

Series is probably better because you'll be able to keep the power more consistent. But you'll need a voltage rail of at least 4X the LED drop, which would be a little more than 24 volts for the constant current driver.

So if you have an (at least) 12.2 volt supply (plus the drop of the constant current driver) you could use two constant current drivers and sets of LEDs in series.

• Thanks. I am hoping to use a single power supply of 12V 5A. Commented Nov 10, 2022 at 23:35

As I understand it, you have a set of 4 LEDs in series and you want to connect another set of 4 LEDs in parallel. Let's assume that you are using a 12v source, in this case you will need to find a resistor that lowers the voltage to the 6.1v value required by the leds, which in this case will be 4.3 ohms 9w, because a current of 4 times the individual value of 350mA, ie 1400mA, to turn on the set of 4 leds in series. For the second set, third and as many as you want, connected in parallel, just repeat the configuration of the first and so on. Until it reaches the amperage limit of the battery itself or source. Anything you can take a look at this site: https://ledcalculator.net/ which is very good.

• Thanks for the answer and link to the ledcalculator, however i need the LEDs to be in series and the calculator only seems to offer a parallel option. Is there a series circuit available on the calculator. Also i am planning to use a 12V/5A power supply Commented Nov 10, 2022 at 23:37