How to use this 8 channel relay

Using Arduino General Electronics
1

I have a 8 channel relay, and i would like to know how to control it with the Arduino Duemilanove.

Here is a link to the product:

1, How do i use this product with the Arduino?
2, Do you recommend to use a external power supply, and why?

2

It just simple

just check datasheet of 8 channel relay driver
provide
vcc 12v-24 (it is mentioned in data sheet varies from9~ 12v)
gnd connected w.r.t 12~ 24 v supply.
just connect any digital pins of arduinoto activate In1 to In8 relay . respective relay will be turned on.

const int buttonPin = 2;
void setup() {
 pinMode(buttonPin, OUTPUT);     
}
void loop(){
digitalWrite(buttonPin , HIGH);
delay(5000);
digitalWrite(buttonPin , low);
delay(6000);
}

you can use multipmeter to check voltage @ NO & NC when pins are high &low

3

I think that you don't need to power this board with an external power supply. You only need 5V for Vcc, so, they can be provided by the 5V rail of the Arduino board. If all the relays are in the on state the board will need +/- 320mA. I believe that the Arduino board can handle this amount of current.

4

luisilva:
You only need 5V for Vcc, so, they can be provided by the 5V rail of the Arduino board. If all the relays are in the on state the board will need +/- 320mA. I believe that the Arduino board can handle this amount of current.

Ill advised in the extreme. Use a separate regulator.

People are forever coming to these forums complaining that their Arduino - or more commonly, an LCD - "crashes" when they switch relays.

This relay board is opto-isolated. It is a really good idea to make use of this facility by removing the link between "COM" and "GND". You feed your relay supply (which need not be connected to the Arduino or its power supply at all) separately to "VCC" and "GND", you connect "COM" to the Arduino GND and the inputs to suitable port pins on the Arduino.

AMPS-N:
just check datasheet of 8 channel relay driver
provide vcc 12v-24 (it is mentioned in data sheet varies from9~ 12v) gnd connected w.r.t 12~ 24 v supply.

You may be sharper than I, but I could not see where it linked to a datasheet. All I could see was under "Overview" where it says 5V supply voltage.

5

I must agree with all that Paul__B said in the last post.