# SparkFun Forums

### NEW GUY here! I need help and just wanted to say Hi!#198783

#198783
Hello my name is Jonathan and I have a question for anyone here that is all the wiser than me.

I need help on powering X5 LEDS from an AC-DC power adapter. The IR LEDS are rated for 940nm and are 1.2-1.5V and they each use 20-30ma current amps.

Would a 6V AC-DC power adapter with 100ma work and be safe? I do not want to add resistors. I am trying to get the LEDS to match the voltage and current based on the total amount of LEDS I am using which is X5. IR LEDS 940nm type. Here is the link. Do you sell one like this I can buy in bulk?

https://www.amazon.com/gp/product/B01BV ... UTF8&psc=1

IR LED - 940nm Infared LED Diodes
(1.2V - 1.5V) Rated voltage

1.2v X 5 IR LEDS = 6V TOTAL
1.5v X 4 IR LEDS = 6V TOTAL

(20-25ma)

20 X 5 IN SERIES = 100ma TOTAL ALL LEDS / PERFECT MATCH TO AC-DC
25 X 4 IN SERIES = 100ma TOTAL ALL LEDS / PERFECT MATCG TO AC-DC
30 X 5 IN SERIES = 150ma OVERCURRENT OF 50ma, 50ma more amps than 100ma
30 X 4 IN SERIES = 120ma OVERCURRENT OF 20ma, 20ma more amps than 100ma

I assume I could use either X4 IRLEDS total or X5 IR LEDS total correct? That would be safe on a 6V 100ma AC-DC Power adapter?
I do NOT want to add a resistor, I am trying to get the amps and volts to safe levels without adding the heat consumption of a resistor too.

### Re: NEW GUY here! I need help and just wanted to say Hi!#198792

By darrellg
#198792
That's not how LEDs work. You can't think of them like light bulbs. You have to think of them like diodes, which is what they are. They have no way to self-limit their current. You have to either use a current-limited power supply, or put a resistor in series to limit the current.

https://learn.sparkfun.com/tutorials/li ... iodes-leds

### Re: NEW GUY here! I need help and just wanted to say Hi!#198796

By deenlee
#198796
Hi, I am new here, too

### Re: NEW GUY here! I need help and just wanted to say Hi!#198863

By davidjames9001
#198863
Hi radioboy86. I am also new here.