How to solve nodemcu will bring interference to the circuit


@Costas I let Nodemcu and RF 433m share a power supply. I used a Led to discover that Nodemcu interferes with the RF 433m module and did not use the RF 433m module to transmit signals to Nodemcu. I now expect to solve this problem.


But GND a Vcc is not enough for the RF receiver to interface with the MCU. What about the data?


@Costas I do not need to transfer data to Nodemcu, I just want to solve the interference problem, this is just part of my circuit, and then I will show you the key part. I found this part of the interference, so I need to solve this problem.


How do you know you have interference if you are not connecting the data lines?


@Costas I use the remote control to transmit the signal to the 433m receiving module,
When the Nodemcu and 433m receiver module shared power, the remote control from the 433m module 0-10cm to receive the signal, and is intermittent, very unstable.
When only 433m receiving module power supply, Nodemcu no power, 433m can be received within 2m remote control signal, and very stable.


You are not making any sense but I will advise accordingly.

As pointed out by others, locate the RF receiver as far away from the MCU as possible. You should be able to locate it several meters from the MCU and still have enough power in the circuit.

You can try powering the receiver from it’s own power supply and up to the maximum voltage. Our transmitters accept 12V, never used the receivers but your maximum might be different. Just provide a common ground to the MCU.

Hope this helps in some way.


@Costas Thank you for your reply, but I really hope to solve such a problem, this problem has been troubled me.
I recorded a video for this purpose. Video can be seen Nodemcu seems to have some interference on 433m


OK I have watched the video and presumably you are saying the LED flashing is the “interference”.

In actual fact we have done some work with RF receivers but most is with RF transmitters.

Some of the interference can normally be “screened out” with software i.e. the sketch you flash to the MCU.

Do you have any details of how the interference is affecting your project e.g.

Expecting 1,1,0,0,1,1,0,0 but picking up 0,1,0,1,0,1,0,1.

Also an extract from your sketch might help.


Yes, this interference can indeed be shielded by software. Your advice is great! I can keep the signal in 2 seconds. But can not solve this interference is also limited the distance, 433m module can only accept 0-40cm within the remote control signal. This is the biggest problem.


@mtrucc Nice video… however are you aware that this is the Blynk (IoT software) forum, not the Blink (flashing LED) forum :stuck_out_tongue:

If you are not going to move those two devices further apart (or perhaps use separate PSU) to reduce the “interference”, then what exactly are you asking of us?


@Gunner Very sorry because i am using blynk. The Then I bought the nodemcu.
The most important thing is, I think you are passionate enough! Haha!
I also considered the use of two power supply, but a work can not always use two power supply, so that is not good. I probably should think of a way to do what a power is isolated.


I’m guessing that the 2.4ghz Wi-Fi transceiver on the NodeMCU is interfering with the 433Mhz receiver. Maybe the 433Mhz receiver is picking-up harmonics from the Wi-Fi transceiver.

You haven’t really said if the problem is solved/reduced by moving the receiver and the NodeMCU a couple of meters apart.

You won’t find me saying this very often, but have you considered trying an Arduino with an Ethernet shield to connect-up your 433Mhz receiver? That way there will be no Wi-Fi signal from the Arduino to interfere with the receiver.



@PeteKnight I thought about that but I don’t like to use the “A” word unless I’m berating them :slight_smile:


I drink coffee while using Blynk… but don’t think I will get too much assistance fixing my coffee maker here though :stuck_out_tongue:

Ah well… Blynk related or not…

Just for kicks, I wired up a 433Mhz transmitter/receiver set that I have had sitting unused for years… and low an behold, although I can still manipulate the pulses well enough to prove that it is sending and receiving a signal, it seems to get a lot of interference that causes my LED to flicker like crazy, with or without ESPs in near vicinity… and even causes issues with the ESP’s connection to my Local Server.

Not sure what I just proved though, except that there is cross RF interference and that yes, I am sometimes too passionate about problem solving, and now I probably won’t let this go until I get it to work without the flickering.

But for now, I think it is time to go finish a movie instead :slight_smile:

Happy RFing (hmmm… that sounded wrong…)


@mtrucc, as i see the problem, your circuit has at least 4 major problems:

  • not using antenna on the rf modules (these modules are useless without a properly soldered antenna. at least solder a 20cm jumper wire on both the transmitter and receiver module)
  • not using any decoupling capacitors in the circuit (the receiver is very sensitive to this, it will not work properly)
  • the breadboard connections are probably not tight enough
  • you do not mentioned what power supply are you using, but as i see in the video: or you have a bad connection somewhere in the circuit, or a fake / faulty psu, which could not provide enough current for the nodemcu board, this is why the led is flashing, not because of the nodemcu generates any interference! you have a huge voltage drop when the nodemcu tries to start, this causes the led to turn off…

take a dmm, and search for voltage drop around the power lines in your circuit. or turn off the power and check the resistance of the voltage lines, between the psu and rf module! you should check even every jumper cable separately for continuity, sometimes they are faulty by factory and this can cause a lots of trouble. what you see in the video, is not interference for sure, its voltage drop!


@Gunner @Costas @PeteKnight
Thank you very much for participating in the discussion in these days and have provided me with a lot of help. I am very grateful to you, and I am sorry for my dedication to worry about you.

In fact, I have some way to solve this problem, but I think I should not casually put this method out, because I can not effectively prove that this method is valid.

I summed up your advice. Finally prepared to use the program + filter circuit to solve this problem.

I used the RC filter circuit to handle (do not know where) the interference. The effect is the LED cycle flicker (using 47uF capacitor and 90R resistor composition filter circuit), according to my calculations, the use of 1000uF capacitor and 200R resistance will be better.
And then use the program to deal with LED, 2 seconds there is a high level signal, then the LED will remain bright.

This is my current method, I really is no way, because I want to Nodemcu and 433m in a sealed box, the use of USB power supply.

If everyone has a better way to keep a message, I am happy to track and work together to solve this problem.

I believe there will be some friends in contact with Blynk when encountered a variety of problems.

Also I have sent an e-mail to me to buy the producer of the Nodemcu module to see if their engineers have no better way to deal with this strange interference.


excellent post.


@wanek Thank you for your help. You’re right I will also see if my 5V power supply can provide enough current and check my circuit.


Yes, very good! Please forgive me too seriously. I just do not expect the wrong way to mislead the friends who come across the same problem


Although marked as “Solved” it’s worth mentioning the characteristics of superregenerative receivers.

As I wrote in my thread RF 433 Mhz on virtual pin doesn’t want to send (with scheduling) but didn’t elaborate, a SRR is by design (or function) very noisy when idle (not receiving). The user metacollin explains it very well on Stackexhange: 433.92 Noise … (last post on the page).

And due to the continuously output of garbage, the function tasked with decoding it will probably get stuck looking for a real signal since it receives all the time. Perhaps it’s my limited programming skills, but using those receivers as more than just stand-alone “print received message and nothing else-program” have been problematic.

My two bits…

Cheap(est) RF 433 Mhz bridge for home automation with both Tx and Rx
RF 433 Mhz on virtual pin doesn't want to send (with scheduling)