Arduino and LEDs circuit schematics review needed

Using Arduino General Electronics
1

Hi!

I'm pretty new to electronics and I'm trying to create a LED display with some simple blinking lights. I just need some help to look over my circuit and if it will work as intended before i try building it.

The idea is for the outermost 8 LEDs to be continuously turned on. The other rows will blink inwards starting with the top one and repeating when getting to the bottom one. This will be controlled by the MOSFETs using the arduino. 220R resistors between Gate and arduino to limit current and protect and then 10kR resistors between gate and ground to keep the MOSFETs off when the arduino isn't driving them.

The power source is 12V, the LEDs have appropriate resistors, i just didn't put them in for space. The transistors are N-channel MOSFET logic gates (probably irl540n). The potentiometer at the arduino is there to control the blinking speed.

circuit (5)
circuit (5)1020×1080 16 KB

2
  • Wire LEDs so each LED has it’s own series resistor.
  • Use logic level MOSFETs.
  • Wire the MOSEFTs as seen here.

IMG_3466
IMG_3466843×1090 57.9 KB

1 Like
3

If you have a 12V or so power supply, it is far more efficient to have 4 leds in series.

2 Likes
4

That, of course, will depend on the Vf of the LEDs - White, probably only 3 per, whereas Red, 5 per.
This may help:
Quora on LEDs

5

Thanks for the reply!
So basically move the pull down resistor to before the resistor going from the gate? Why is this preferable?

For the LEDs I have appropriate resistors before each LED, I just didn't draw them in the diagram to save some space.

6

Regarding LEDs in series, sure, i know i could have better efficiency doing series of LEDs in parallel but the way this setup is going to be used I'd rather do everything in parallel.

7
  • Doing it your way creates a voltage divider.
8

If a bank of LEDs shares a resistor the current to each is not controlled - only the total current. As the intensity is proportional to the current you may find some are brighter than others.
You can only do this if they are all the same type - and color.
A much better way would be for the leds to be in series, that way the current through each is the same.

You havent said if you intend to use different colors - it matters. best if you share a link to the types you intend to use.