Electronic – arduino – Relay sla-05vdc-sl-c is not working on arduino uno and nano

arduinorelaywiring

At first time, trying to check this relay modules (I got 2 the same) they both worked nice – no problem.

Relay

But now I am going tu build the temperature controller for old fridge (it is working constantly). I got the problem: both LEDs (red indicates relay being ON and green – indicates POWER ON) are working, but there is no connection between NC and COM.

Does not matter HIGH or LOW jumper position.

At first tests I wasn't used any resistors, and everything was fine. Voltage between DC+ and DC- are about 4.7 V. Between DC- and IN – about 4.5V.

At first I was sinking about not enough current form Arduino NANO with miniUSB, but the same result.

So, I have this schematic (have tryied some pins – doesn't affect anything.

schematic

simulate this circuit – Schematic created using CircuitLab

I have tested using this code:

int testpin = 7;

void setup() {                
  pinMode(testpin, OUTPUT);// initialize the pin as an output
}

void loop() {
  digitalWrite(testpin, HIGH);//turn on
  delay(5000);// wait for 5000 milliseconds (five seconds)
  digitalWrite(testpin, LOW);//turn off
  delay(5000);//wait five seconds
}

So, have I burned my relays?
If I use 4 1,5 batteries to check it working – it cannot damage anything?

How exactly wire this relay?

Should I try to use solid-state relay (and how to manage it working)?

Best Answer

Thanks Ignacio Vazquez-Abrams and Spehro Pefhany for your advices!

So, I have reconnected all wires and seems one relay I got is broken now (I suppose I have done short circuit)...

Now, when the signal is ON I have connection between NC and COM.

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