I got this "Relay Optocoupler Module for Arduino 5V":
With this inputs: DC+: positive power supply (VCC)(5V) DC-: negative power supply (GND) IN: The control end, the driving current should be more than 4mA COM: The control of loop of earth wire
So as much as I understand when I apply 5v on DC+: positive power supply (VCC)(5V)
then relay will close interface AC 250
So why I need two other inputs?
IN: The control end, the driving current should be more than 4mA
COM: The control of loop of earth wire
So why I need two other inputs?
IN: The control end, the driving current should be more than 4mA
COM: The control of loop of earth wire
You mean IN and COM ? Well i'm not sure but i think you only need to use IN.. You will leave COM and GND with the Jumber on, as it is..
IN is used to receive a digital input from your arduino..
This board is not just a relay. It contains other important components and functions, an opto-isolator and a driver transistor.
The driver transistor permits you to control it with a current much less than the relay naturally requires. The opto-isolator allows you to electrically separate the control circuit from the power supply that operates the relay. The circuit is essentially identical to this one:
except that the connections which go to the opto-isolator are labelled differently! {"IN4" in the diagram corresponds to "COM" on your board, and "VCC" in the diagram corresponds to "IN" on your board!} There is also a pilot light on the power.
In fact, you can use it in either of two ways.
Ignoring the jumper for a moment, you always connect VCC to the 5V supply for the relay and GND to the ground (negative) of that supply. You can either connect "IN" to an Arduino output pin and "COM" to the Arduino ground in which case the relay switches on when you send the output HIGH, or you can connect "IN" to the Arduino Vcc and "COM" to an Arduino output, in which case the relay will switch on when you send the output LOW.
If the relay ground and the Arduino ground are the same, you can use it with the link in place and have the relay operate with a HIGH output, but you lose any advantage to having an opto-isolator. In fact what you should do at the very least, is to connect "COM" separately to the Arduino board ground, and "GND" directly to the ground at the relay supply.
It is not recommended to power the relay Vcc from Vcc on the Arduino if you are providing the Arduino power through Vin.
Are you here to comment on people who are trying to help others ? On a negative way ? I don't think So !!!!
We are here to help each other as much as we can, that's all !!!!
Also if you see in my initial post i say this : Well i'm not sure but ... , which means obviously i don't know a lot about the relay !!!
Finally according to what you said later , i wasn't wrong ... And yes it seems you know more about the relay... Well done !
In a case of "switch on when you send the output LOW.":
I connected "VCC" and "IN" to the Arduino 5V supply and GND to GND.
and "COM" to an Arduino output pin, in which case the relay will switch on when I send the output LOW.
But the problem that all the board of relay turning off.
Is there any other way to switch on when you send the output LOW but not to turning off all the board?
flash_os:
But the problem that all the board of relay turning off.
I'm not sure what you mean by "all the board of relay turning off". Can you explain that a bit more?
Since the website you obtained the thing from gives absolutely no information (i.e., circuit) on the board itself, it is possible that the connections are somehow different. A couple of good photographs of each side of the board would help to figure things out, taken from vertically above in good light by a camera at maximum zoom from about a metre away, with perfect focus and sized to no more than 800 by 600 resolution.
