Relay problem.

Hi, first time trying to use relays.

Got this PCB: All components are as the PCB tells me.

When I connect the board to my arduino uno I can only see a very dim blink on the diod and no click sound from the relay.

Code: digitalWrite(7, HIGH); //connected to CTRL pin

Connected GND to arduino GND and 5V to 5V

If I connect the CTRL pin to 5V the relay works

Is the current to low from the arduino pin7 to controll the relay board?!?! I power the Arduino from USB and I tried external 5V aswell (1A)

What should I try or fix, iam stuck.

First you need to check with only a led and a resistor (180/220 Ohm) if the output is turned high. Have you defined the port at output ?!

If the led is litt like it should, you know your sketch is working.

You need to check if the arduino can deliver the current needed for the relay to switch. Be aware of the fact that is the voltage to the relais switches to "low", there can be an enormous voltage spike that can ruin you're arduino. Check on the forum and site how to avoid this by using a decoupling diode with maybe a transistor to switch the relais.

It is always best to deliver the complete code between code block tags!!!


Code: digitalWrite(7, HIGH); //connected to CTRL pin

Have you first done:- pinMode(7,OUTPUT); somewhere in setup()

Yhaa....I missed to define the PIN..

Now I feel stupid!

Thanks alot.