In iNet I only see drawings with one LED strip and an electrolytic capacitor. I’m looking for an example how to integrate/cabeling an electrolytic capacitor, for example - when we are using 5 long LED strips.
Thanks!
Similar theme: wled.discourse.group/t/does-this-capacitor-really-required/2964 | forum.arduino.cc/t/multiple-led-strips-and-external-power-supply/906283/10 | forum.arduino.cc/t/verify-electrical-schematic-for-led-strip-project/1159874
#wled #elco #capacitor #scheme #drawing #wiring #led #project
this answers it, its optional. if you have 5 strips, put one at the beginning of each strip
1 Like
You don’t need the capacitor, it won’t hurt but probably it won’t do anything because electrolytic capacitors (especially the cheap ones you get on Amazon) are way too slow to respond to the switching speed of addressable LEDs. What’s needed are ceramic capacitors, which are much faster, and that is why most strips include those already.
It’s like the Arduino optocoupler disease where the Internet is full of random Arduino optocoupler circuits where the optocoupler doesn’t actually do anything because people copied some random Arduino circuit.
Case in point from the link:
Add 500-1000uF (6-10v) capacitors to the strips 5v pins. The resistor is for strip input protection, suggest you use two resistors, one for each strip.
1000uF capacitor and add two resistors to the same data line, double the protection 
not entirely true. the capacitor can help to stabilize power fluctuations on cheap powersupplies. Not PWM speed but animation speed, think: strobe effect.
If the goal is to stabilize a power supply (which is questionable, capacitance on an unknown control loop can also degrade its stability rather than improve it), then you want to put the capacitors close to the power supply’s controller. Putting them on the strip would reduce their effectiveness because the capacitance would be isolated from the loop by the wire impedance.
Putting it on the strip makes sense if the goal is to filter out the strip switching noise, but at least on the ws2812b I probed it and found it made negligible difference (few millivolts RMS), mostly because the switching noise is pretty high frequency and electrolytics aren’t good at high frequencies. Conversely 100 parallel 100nF capacitors might only be 10uF (or 100uF if they actually used the recommended 1uF size), but their parallel impedance is on the order of a million times less than a cheap electrolytic, so their parallel combination is much more effective. They also don’t really strobe all at once due to the pixel transmission delay, they switch sequentially, so you get a lot of fast, small changes in current that small capacitors absorb very effectively.
1 Like
what you write is mostly correct. that is why its optional. it helps sometimes (there are users reporting the cap fixing issues in their setups).
that is incorrect, all leds switch more or less at once on color change.