Hi,
New to the forum here and in need of some advice
I have a ESP8266 as a controller, running a WS2812b led strip with 135 leds
I used a 5v 100w power supply i had laying around for testing and all works perfect. But this powersypply is a massive overkill and with a power draw ofmax 2.75Amp, im looking for something smaller
Gone and bought a 20w (5v 3A) power brick, the output is 5.5v.. connnecting this cause the lights to have a mind of their own.. sometimes its working, sometime only one light dimly one glowing greenish, and other times none at all.
Connecting back the big power supply, all back to normal
So guess 5.5v is not suitable? How do i drop the brick by 0.5v to have constant 5v? Looking at regulators that can handle 3-4A, its almost cheaper to look for another power supply..
do you have the required capacitor at the head of the LED string? I think the usual recommendation is 300 uF, but I might be off on that. That cap provides extra 'oompf' when the LEDs all turn on (nearly simultaneously). Your big supply probably has enough reserve that it doesn't sag, but the little one will.
you bought a 3A supply for a 2.75 A load. Hmm. Recently, I've noted a significant number of supply comments on Amazon indicating that the purchased supply didn't anywhere come close to meeting it's rated current, so that might be your problem. I'd be looking for something 2x the calculated requirement, but that's just me.
Usually, a series resistor is recommended for the digital line feeding the string, as well. Around 300 ohms, IIRC. Do you have that in place?
As for 5.5 V, I doubt that's the issue, but you could always just put a series diode in place for a test. 1N5401 comes to mind, IIRC that's a 3A diode. A little long in the tooth, but it should do what you want.
@DVDdoug The diode drops the supply voltage, not the signal voltage, as the OP was worried that the 'brick' output voltage was too high. Signal level is a completely separate issue. I don't know if the LEDs will 'like' the ESP signal voltage, never tried it.
I've got a similar setup (ESP-01 to 144 LED strip) and the 3.3V only goes to the first LED and is sufficient for logic (the input voltage threshold is actually quite low). Dout of the first LED is 5V, thanks to Vcc.
Yes i agree, that will be the absolute max the strip can draw, but Im running the Leds at 70% only, and measured the current over a period of time with various effects, highest i got was 2.75A
All works perfect with the big psu, but with the brick its acting random, lightning leds at random some times
I will try the diode, just to rule out its not because of 5.5v instead of 5v
If you have a digital volt meter or multimeter, monitor the 5V power when the flickering is happening.
I'd suggest lighting one pixel at a time, slowly ramping up the number lit, to see if it consistently starts to falter at a particular level. Then you can back-calculate the current at that point.
Should take all of 5 minutes to cobble up a loop that does that.