# How do I make a 6 LEDs Parallel circuit

I did a simple 6 LEDs parallel circuit but I am a bit confused. I must remark that I am a total NOOB but I made some research on LEDs, Voltage and Resitor calculations before weld the circuit.

The circuit is already welded and works, but I would like to know if I did it well, or if it is an other or better solution.

Here are the mockups I did before welding, finaly, I decided to do the Option A.

Wich option would you consider to be the optimal?

Components I used:

• 4 batteries of 1.5 volts
• 6 Leds of 3.7v at 20mA
• 6 Resistors of 120 ohms

For the last example:

• Resistor of 33 ohms

EXAMPLES

• A and B are practically the same. C doesn't guarantee that the current will be evenly distributed through the LEDs. It might work for a while if the LEDs are similar enough. If they aren't, they'll probably start burning out one by one. Commented May 27, 2017 at 2:26
• Also, note that weld != solder. Commented May 27, 2017 at 2:27

A & B are electronically the same. Position does not matter.

C is not always recommended. The diode with the lowest Vf will set the voltage across the parallel leds. If you badly mismatch them, you will get one diode that conducts more current than the others and can lead to one burning out then the rest following. This is really overblown (pun totally intended) fud. Parallel leds with a single resistor is common. Just match the leds for brightness by eyeballing them, then confirm that the voltage across them are fairly identical. For one off projects this is enough. All it requires is careful selection of parts.

A/B is ""safer"" but C requires less parts. You are fine as is.

• Thank you so much, you took a load off of me. In the future I will like to add a switch and sound, It would be cool. Commented May 27, 2017 at 2:44
• No, even in unmatched LEDs (of the same type) you can't ever burn one out because one hogs the current, there is simply too much internal series resistance. The internal resistance acts just like a series resistor and providing the LEDs are the same Vf category you will be fine. There are simply millions of LED torches that that use an Option C type circuit for up to 24 LEDs in parallel. Commented May 27, 2017 at 3:01
• @jack I did say it was FUD, and as long as you do some matching they will be fine. Commented May 27, 2017 at 3:02

Option A and B are electrically same. As long as you limit current per LED it should be fine.

Option C is not optimal as it may not provide (electrically) even brightness to all LEDs in the circuit.

Option A and option B are providing optimal current to EACH LED.

In case you are using a micro controller to drive LEDs, you may think about limiting drive current using PWM if your micro controller supports it. If your micro controller supports it, you can eliminate resistors.

• Sorry for my ignorance, but what is a PWM?, and a micro controller could be and Arduino or similar? I'm just asking, that way I can do a research on the topic and learn more :D Commented May 27, 2017 at 3:11
• @AbielMuren PWM is Pulse Width Modulation. It can be achieved using microcontrollers to limit current to output devices. Read more here - arduino.cc/en/Tutorial/PWM From Wikipedia - en.wikipedia.org/wiki/Pulse-width_modulation Commented May 27, 2017 at 3:14
• Ohh, I see, thank you, I think I must go to the store and grab some tools and an arduino board to learn some good stuffs Commented May 27, 2017 at 3:21