Problem with relay

Other Hardware General Electronics
22

Not yet, but are you sure this is the correct place to add it? Shouldn’t it be added between + and - wires going to the pump?

23

You stated that the problem does not occur when you set the pin low and the motor is running. So it must have something to do with the relay contacts opening and closing when connected to the motor. The diode will prevent excessive arcing (sparks) across the relay contacts when they open or bounce. The arcing may be causing interference with the Arduino causing it to reset.

24

I have only 1N4148, will it be enough?

25

That should be OK for a small motor.
Make sure you get the polarity right. The cathode (end with the band) connects to the contact that goes to the battery

26

It still doesn't work, it turns off immediately
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27

Well let's eliminate the breadboard. Sometimes they have bad and intermittent connections.
Connect the RED wire from the battery directly to the relay screw terminal.
Connect the BLACK wire from the battery directly to the pump.

28

The diode should be connected across the pump terminals with cathode (end with black band) connected to + and other end to - (negative).

29

I have tried it like few minutes ago and it is not working perfectly, but works better (like 5 out of 10 times instead of 0).

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image1904×1162 353 KB

30

How is the Arduino powered?

31

USB from computer

32

Is the relay opto isolated?

33

Did you eliminate the breadboard?
With the diode across the relay.

34

It is not

35

I eliminated the breadboard with both diodes and it is also like 50% success rate

36

Could be problem but if diode is installed and working correctly, should not.

37

Do you have another relay or an NPN transistor? Maybe the diode on the relay module is bad.

38

I don't have other relay but I will buy one with opto isolation tomorrow. I have an NPN transistor. What do you think about adding another diode in the circuit which powers the relay?

39

Well let' see if the Arduino is actually resetting
Try this code
Set the serial monitor to 9600

#define pompa 5

void setup() {
  pinMode (LED_BUILTIN, OUTPUT);
  pinMode(pompa, OUTPUT);
  digitalWrite(pompa, HIGH);
  Serial.begin(9600);
  Serial.println("**RESET**");
}

void loop() {
  digitalWrite(LED_BUILTIN, HIGH);
  digitalWrite(pompa, HIGH);
  delay(2000);           
  digitalWrite(LED_BUILTIN, LOW);
  digitalWrite(pompa, LOW);
  delay(2000);
}
40

it is
image

41

So it's EMI from the relay/motor
Move the pump and relay as far away from the Arduino as the wires will reach an put something metal between them
See what happens