So I was reading about LED strips and came across this on AdaFruit: http://learn.adafruit.com/adafruit-neopixel-uberguide/power
Specifically: Before connecting a NeoPixel strip to ANY source of power, we very strongly recommend adding a large capacitor (1000 µF, 6.3V or higher) across the + and – terminals. This prevents the initial onrush of current from damaging the pixels.
I’m no electronics expert, so I was looking for opinions since I don’t want to burn out my tree project.
Personally, I’d say it’s a good idea in terms of cost/benefit and protecting your investment in hardware. Actually, it’s a generally good idea to do this across every power supply connection, I think: not just to the LEDs, but also probably on your microcontroller, too. Many microcontroller boards have (smaller) capacitors on them for similar reasons.
But I’m a CS guy at heart, not an EE.
The only real claim I have to an EE is the one that in the middle of “GEEK”.
Adding a large cap is always a good idea. But as Mark said, this is also true for any kind of power supply. Look at any regular data sheet, they all recommend (some require it) a cap both on the input and output. Ripple and surges can be devastating.
Is the capacitance to use dependent on the number of pixels or voltage or…?
So, the capacitor is there to absorb some of the ripples that the LED strip will cause. Voltage and current go hand in hand in the sense that, the more current you demand, the less voltage you have. So when you turn on an LED strip at full power, the current surge needed to do that will cause the voltage to drop. In some cases that voltage will drop just enough to where the controller’s Brown Out Detector will trigger and shut off the controller momentarily. This is really important when you are running everything off of the controller as opposed to a separate voltage rail, but it does apply to both cases.
The capacitor is there to act as a buffer so that when you suddenly request a large amount of current, it can help supply that without causing the voltage to sag too much.
Since with LED strips you could potentially be dealing with pulling a few amps, having a 1,000uF/10V capacitor available will be very helpful here. It’s just a very brief surge, in milliseconds … So you just need something large enough to handle that in addition to what the supply itself can provide.
Thanks for the detailed explanation. I’ve added a cap at both ends to protect my investment. I will also add this to the stuff needed for every project.