Arduinos and Relays

Forum 2005-2010 (read only) Hardware Interfacing
1

Hello All,
Ive recently been posting alot and my lil project is coming along well i finally got my lcd screen working
properly with the arduino. So now this is what i need. I'm tryin to drive some about 5 relays with the arduino
so they act like switches i found one page diagram about how Arduino Playground - HomePage
but its not working properly. We have a 12V relay. I was wonderin are there any other ways to do this.to drive the relays
and controll them.also is there a way to program the arduino to name the Relays in code like relay1(on) or if anyone has any ideas
just let me know any suggestions or better ideas.

Also the arduino should be able to accept a load right but the load or one of the compnents could be to much for the arduino as well couldnt it.
In inturn that leads me to my next question so does the arduino have a protective mechanism like a fuse inside that will cut all output?

2

arduino have a protective mechanism like a fuse inside that will cut all output?

No any overload will permanently damage the Arduino. There is an absolute maximum of 40mA per pin but I would stick to only 30mA. The chip as a whole can only give out a total of 200mA.

That schematic is about as simple as you can get to drive a relay. If it is not working properly then you are doing something wrong.

Does it work with just one relay?

is there a way to program the arduino to name the Relays in code

Yes there is an almost infinite number of ways to name relays. If you want to use a command like realy(number, state); to turn on a relay all you have to do is to write a function:-
void relay(int number, byte state){
digitalWrite(number, state);
}

Ive recently been posting alot

So you you have a new account? Your total number of posts only shows up as 3.

3

could you show how you hooked the relay up exactly ?
And maybe also your arduino code.

You are using an external power supply for the realy right ?
This is a must!!

And also a transistor that can handle the current / voltage you ar dealing with.

To do the "Relay1(on)" stuff you could create your own functions in your Arduino code.

Or you could cretae one function that took the relay number as a parametre, like

relayOn(relayNumber)

4

Grumpy beat me to the finishing line - again :slight_smile: