SparkFun Forums 

Where electronics enthusiasts find answers.

By webmastadj
#190345
I am looking to string LEDs in a series. I was wondering what type of power would be needed for this? Assuming each LED is 3.3V, does that mean for 4 LEDs I would need 13.2v? I have googled this just can't seem to find a straight answer.

update: I did some tests with the 5v output on the Arduino and I could do two LEDs without an issue which is expected based on the 5v output. When adding more, no light. How would one use say a 5v power source and power more than 2 LEDs or a 12v power source with more than 4 LEDs?

update 2: I was able to get the all to light up in parallel...I have 5 running in parallel right now. I am assuming this would work without issue.

Thanks.
By skimask
#190359
If there is ANYTHING in this world that is Google'able these days, it's how to hook up LEDs.
Series, parallel, serial/parallel, stacked, unstacked, different colors, blah blah blah.
It's all there in literally hundreds of thousands of millions of billions of trillions of tutorials, DIY pages, how-to-pdf's, etc.
By webmastadj
#190363
I skipped googling and just tried it. I wasn't getting a concrete answer on google. I will be running them in parallel (for now). Just swore I read somewhere that parallel was a bad thing. I did notice I still need to use a resistor with each LED instead of just one in series with the GND/- terminal. The lights are dimming as I add more when only using a single resistor not sure why that is.
By webmastadj
#190447
Thanks for the link, that helped a great deal to understand it!
By stellajohn
#191577
LED connection with power depends upon your requirements if you want to light up for some more time and you have current then use in series but if your have limited voltage then use parallel method also you need precise value of resistors for any type of connection.