Building a VU meter

Question

I am building a VU meter with two 5v neopixel rings, two potentiometers, a headphone jack and an Arduino nano. Will 5 volts 1 amp cut it, or do I need more power? FYI I'll be powering it via a DC jack once I get it working.

• chrisl: How many LEDs are in each of the Neopixel rings?
• dandavis: It should be enough if you avoid white and use single-color zoned metering.
• taran: they each have 24 led's on each ring and what is single-color zoned metering?

Answer 1

Normally the maximum amount of current a typical LED can withstand is 20 mA. This means per color and per LED.

So if you have 60 LEDs, than you get 60 (leds) * 3 (R/G/B colors) * 20 mA = 3,600 mA. To give some headroom I would use a 4A or 5A adapter.

However, note that probably 5 mA or 10 mA per LED would be enough to be very good visible, unless you want it to be as bright as possible.

• taran: 4A or 5A at 5V?
• Michel Keijzers: 4A will give 10% 'headroom', 5A even more. In electronics it is better to be safe, probably 4A will be ok, if you want to be sure/safer, use 5A. You could do some tests when switching all LEDs on, under different temperatures, and find out the worst case. If you don't want to do such testing, use 5A.
• taran: so i would need 5A if i want to power the nano off of the same supply?
• Michel Keijzers: @taran i don't know how much the nano used, but i think it's not much... Add it up to the LEDs per usage and use some headroom.
• taran: total A with per io pin 3,640 so i would need a 5v 4a power supply, correct?