Strange relay

Using Arduino General Electronics
1

Hello,

I got this relay today, and am trying
to connect it to arduino all afternoon and
no success.

See photo attached.

There is a ton of material about classic relays
and how it works. Mine has additional COM pin on
the control side, and i don't know where to connect it.

I connect INT1 to D4, GND to ground and VCC to 5V
on arduino nano, and COM1 to battery +, to NO1 wire which goes to
resistor and led and then to battery -.

I use this code:

const int relayPin = 4;

void setup() {
Serial.begin(9600);
pinMode(relayPin, OUTPUT);
}

void loop() {

digitalWrite(relayPin,LOW);
Serial.println("change_1");
delay(1000);
digitalWrite(relayPin,HIGH);
Serial.println("change_2");
delay(1000);

}

and LED is not blinking.

Please help!

Regards, Jernej

DSC_0046.JPG
DSC_0046.JPG1185×1513 543 KB

2

You could start by watching my YouTube video #18 all about relays - the picture you show is not identical to the one I use but probably close enough to let you understand more about how they work in general. There are loads more videos all about things you can do with Arduinos there too, which you may find useful.

The video URL is in the signature of this very post. Enjoy. Others will no doubt give you more information about your precise problem.

However, the COM connection stands for COMMON and is the input of the relay (eg +ve) that is then switched from the NC (Normally Closed) relay switch to the NO (Normally Open) relay switch. Think of it as a two way light switch and you may get the idea.

And if that means absolutely nothing to you then you definitely need to watch the video and understand how relays work in general.

3

I managed to make it work:)

Here's how:
connected D4 to int1 and arduino 5v to com, battery+ (12V) to vcc and battery- to GND.
It needs 12V to work.

Regards!

Jernej

4

Here's how:
connected D4 to int1 and arduino 5v to com, battery+ (12V) to vcc and battery- to GND.
It needs 12V to work.

Without a schematic or datasheet, or more information, I don't know. And, it depends on what you're switching/controlling. If it's working, OK.

There is a ton of material about classic relays
and how it works. Mine has additional COM pin on
the control side, and i don't know where to connect it.

It's not just a relay. It's a relay board with a driver circuit on it. That's fine, because most relay coils require more voltage & current than you can get directly from the Arduino.

Do you have a datasheet, or did you just buy a cheap-unknown board with no documentation off ebay?