Analog LED stripe is pulsing with an ESP01 connected to the same power supply

[rkk2025]

Hi, I have an RGB stripe that I want to control via Wifi. To make this useful I wrote an DreamScreen Device emulator (GitHub - rkkoszewski/ESP01DSEmulator: An unofficial DreamScreeen Sidekick Emulator for an ESP01 + Arduino (For testing)) which lets me control and sync it with other DreamScreen devices at home.

The basic setup is: A 12v input, this is connected to a Led Stripe Driver (Previously implemented with an Arduino nano and Mosfets), then a linear regulator that is connected in serie to the same 12v input and feeds 5v into an ESP01 adapter that finally has the ESP01 connected to it. Finally that ESP01 is connected via serial/data connection to the Led Stripe Driver to control the lights.

Everything works fine if it wouldn't be because the lights are constantly pulsing in light intensity. The pulsations are random but frequent, and are not very strong, but within a dark room its quite noticeable and makes everybody feel dizzy and unwell.

I don't have the skills to properly write down the schematics of my setup, but I will attach some pictures of the setup on a Protoboard. (Please note, the thin wires of the protoboard can also make the pulsations stronger, but I have the same setup on a prototype PCB with thick copper lanes and the same issue persists there, so it must be something related to how I wired everything).

Due to the fact that the light controller and the ESP01 work separately, it is possible to test how the light behave when I remove the ESP01 while the lights are on, and with the ESP01 removed, the pulsations are gone. At first I thought it could be a software problem, and its the ESP01 changing the light intensity for some reason, but removing completely the communication lanes from the ESP01 or completely removing any communication from the ESP01 sketch yields the same result. I disconnect the ESP01 and the pulsations stop and the moment put the ESP01 back into the socket, pulsations start again.

The connection of the lights and ESP01 is in paralel, so it should not influence intensity as far as I understand.

Does anybody know or could point me towards the right direction regarding what is wrong in my circuit or what could potentially cause this pulsations? I even tried to add a Capacitor into the mix between the output of the LED lights with the hope of stabilising, but nothing.

Thanks for any future hints.

[Wawa]

Decoupling capacitors on a linear voltage regulator are not optional (see the regulator's datasheet).

And the ESP needs a fair amount of buffer capacitance to bridge the ~400mA transmit spikes.
I would use 220uF or 470uF, close to the ESP.
Leo..

[DrAzzy]

How is the LED strip controlled?

Is that 5v from the regulator also powering the logic on that LED driver board? That would present a plausible route for the noise on the 5v rail to cause changes in brightness of the LED strip.

Wawa:
Decoupling capacitors on a linear voltage regulator are not optional (see the regulator's datasheet).

And the ESP needs a fair amount of buffer capacitance to bridge the ~400mA transmit spikes.
I would use 220uF or 470uF, close to the ESP.
Leo..

220uF is way overkill.

47uF is plenty!

But you absolutely must have decoupling caps on the regulator, per the datasheet. Many regulators are picky about what kind of caps they have (some require ceramic caps, others require non-ceramic caps).

You probably also want a larger cap on the 12v, 100uF ~ 470uF in addition to whatever smaller cap is spec'ed for the regulator.