Capacitor size for NeoPixel

[bwarbuck]

I am building a reactive light strip with a full reel of 30 LED per meter Neopixel strip. The diagram shows a 1000 mF capacitor. I have 100, 220 or a whopping 4700 mF capacitors. It is really inconvenient to string together 4-220's and 1-100 mF in parallel. I am using the 10 Amp, 5V power supply from Adafruit... can I just use the 4700 mF? I have read elsewhere that you should use 0.1 mF per LED, so in theory that would be 150 mF so I could just use a 220 mF. I don't want to damage the LED's so any help is appreciated. I could order a 1000 mF capacitor but I am impatient... ;-) Thanks for any input.

[dastels]

Using the 4700 uF should be fine. It's there to absorb any initial surge when power is applied to the pixels... to avoid jolting them. Although parallel capacitors to add up, the small ones are there to filter high frequency noise from the power line. That noise is generated by the PWMing of the LEDs which is why the small caps are next to the pixels. Also, the little caps aren't really in parallel, they are separated by a bit of the power lines. The biggest disadvantage of using the 4700 uF cap is that it's larger than a 1000 uF. That may or may not be a concern.

Dave

[bwarbuck]

Thanks Dave. The 4700 mF will definitely work for protecting the LED's. I am going to have a reactive approach so it will be modulating the LED's quite a bit, depending on the chargeup characteristics of the capacitor, it will be interesting to see if it changes the colors or slows the rate of change in any noticeable fashion... We will find out! Thanks again.

[dastels]

That capacitor will have no effect on the operation of the NeoPixels. It just makes the initial application of power gentler. Once it's charged and the voltage across it is 5v it doesn't play a role.

Dave