12v relay and motor grounding

Using Arduino General Electronics
1

I'm having a silly problem trying to control a 12v motor with a relay. The positive side of the motor is wired to the Normally open terminal of the relay. The relay turns off and on with the code below. I have connected the other side of the motor to each of the ground pins on my arduino, to the dc- pin of my board, as well as anywhere else I thought might complete the circuit, but the motor never turns on. It does work when wired directly, without the relay.

There must be an obvious solution that is just too obvious for me. What is it?

I am using this relay http://www.amazon.com/dp/B00VNDFEIG/ref=sr_ph?ie=UTF8&qid=1465230897&sr=1&keywords=relay.

I am using the following code from Yourduino:

#define RELAY_ON 0
#define RELAY_OFF 1
/-----( Declare objects )-----/
/-----( Declare Variables )-----/
#define Relay_1 2 // Arduino Digital I/O pin number

void setup() /****** SETUP: RUNS ONCE ******/
{
//-------( Initialize Pins so relays are inactive at reset)----
digitalWrite(Relay_1, RELAY_OFF);

//---( THEN set pins as outputs )----
pinMode(Relay_1, OUTPUT);

delay(4000); //Check that all relays are inactive at Reset

}//--(end setup )---

void loop() /****** LOOP: RUNS CONSTANTLY ******/
{

digitalWrite(Relay_1, RELAY_ON);// set the Relay ON
delay(1000); // wait for a second

digitalWrite(Relay_1, RELAY_OFF);// set the Relay OFF
delay(1000); // wait for a second

}//--(end main loop )---

2

Does your program control the relay board correctly. Your sketch looks ok, but does it fit the relay board.

Have you any means of measuring voltage? You could measure voltage on motor terminals.

Then you could measure resistance between relay contacts. (Without 12V or you break your Digital multimeter.)

Edit: Of course you could take photo of your system. Then it could be obvious

3

The positive side of the motor is wired to the Normally open terminal of the relay. The relay turns off and on with the code below. I have connected the other side of the motor to each of the ground pins on my arduino, to the dc- pin of my board, as well as anywhere else I thought might complete the circuit, but the motor never turns on. It does work when wired directly, without the relay.

The relay board takes 12V across the DC+ and DC-
The arduino GND connects to DC - terminal
Each relay can be individually configured as ACTIVE HIGH or ACTIVE LOW (with the jumpers)
What is NOT clear from your post is if you are using the SAME 12V P.S. for both the relay board AND the motor ?

If so the POSITIVE side of the motor should NOT go to the N.O. contact.
It should go to the POSITIVE terminal of the 12V supply.
[EDIT]
The NEGATIVE terminal of the motor should go to the N.O. terminal of the relay.
The COM terminal of the relay should go to the NEGATIVE terminal of the 12V P.S.

When the relay energizes, the motor is grounded by the relay contacts.
That is the standard method of controlling a motor with a relay. Most people (these days) DO NOT use relays to control 12V motors. They use mosfets.

We DO NOT KNOW ANYTHING ABOUT YOUR MOTOR .

4

Please post a drawing of your connection, hand drawing is enough.

This is the way I normally connect the relay to Arduino.

1024×401 172 KB

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