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Stable Power Supply for NodeMCU

PostPosted: Sat May 02, 2020 5:31 pm
by Ben39483
Hi all,

Before I completely give up my small project as I'm pretty desperate right now, I would like to give it a try and ask you :-)

I have
Sorry it is in German, the important stuff is:

PowerSupply provides 6 VDC/ max. 0,7 A (4,2 W). Based on different boards it seems to be possible to safely connect the 6V to the Vin of the NodeMCU. If I do so, the NodeMCU boots, but as soon as I connect to its AccessPoint it restarts immediately. So I thought (based on this video https://www.youtube.com/watch?v=wf_msvWv1jk) I can connect Battery+ to a 440µF capacitor (I currently have only this one) and then to Vin of NodeMCU. Then the NodeMCU works much more stable.

But when I connect
    VCC of the relay to NodeMCU 3V3
    IN1 to D7
    Gnd to Gnd
the relay is kind of flickering (the LED is turning off and on quickly and the relay makes a sound) as soon as I connect via WiFi to the NodeMCU.

For me it looks like the power supply is not stable enough, because as soon as I replace the PowerSupply with a simple USB PowerBank or with USB of my PC everything works fine.

So my question is how to improve the overall stability when connected to the 6V PowerSupply (as this one gets charged by solar panels)?
Already tried to use the external power supply method for the relay (in my case the same which is powering the NodeMCU but with 6V reduced to 5V by using a voltage divider see option 3: https://www.kollino.de/arduino/4-8-kana ... anleitung/ but it didn't improve the stability).

Is there e.g. a simple breakout board available which I can use between the PowerSupply and the NodeMCU?


Re: Stable Power Supply for NodeMCU

PostPosted: Mon May 04, 2020 11:43 am
by AcmeUK
This may not be what you are looking for BUT

I am running a ESPdurino 32 from a 6v solar panel using this shield:-
eBay item no 312174929780

The ESPdurino 32 is a ESP32 on a Arduino form factor board.

My solar panel 6v input feeds into the battery shield's microUSB input.

However I am not switching relays.

Re: Stable Power Supply for NodeMCU

PostPosted: Sun Aug 02, 2020 7:14 am
by KapakoProf
I have a similar situation.
1. 12V powersupply is feeding relay board
2. 5V output of relay board is feeding NodeMCU
3. 3V output of NodeMCU is supposed to drive 1 or 2 CJMCU boards

While readings from CJMCU (sensor) are not stable I investigated all kinds of stuff. From coding, to used pins and finally the 3V output. When connected like mentioned output fluctuates in range 2.96V to 3.3V, which is not stable enough for CJMCU. 5V input is stable.

When adding a USB connector to NodeMCU output is stable at 3.3V.

Next steps to investigate:
1. check if all 3V pins on NodeMCU have same issue
2. add 12V to 3V converter to design to drive CJMCU