relay board GPIO

Dear all,
are there anyone that try to connect a relay board with mini2440 using GPIO
interfaces?

You will not be able to connect a relay to the board directly.

I am not sure how many mA (mill amps) drain one can source from one of the
IO pins on this board but I would assume it would only be a few.

A simple method of switching an external relay would be to use a small NPN
transistor to drive it.

Connect the relay's coil between the collector of the transistor and a
suitable supply voltage's positive rail (i.e. if you're using a relay with
a 5 volt coil, then you need +5v here)

The emitter of the transistor can be tied to a common ground (common to
both the board and the supply voltage for the relay)

The base of the transistor can be connected via a resistor (10kOhm should
work fine) to the IO pin on the board.

This is a rather crude solution to what you're trying to achieve and some
people (including myself) would recommend using this method but instead of
connecting the base of the transistor to the board, rather opto isolate
them from each other.

The latter will protect the board from interference and overvolgage.

Another simpler solution of giving some protection is to also add a diode
between the board and the transistor thereby allowing current to flow from
the board to the transistor but not the other way around.

Thanks yuo for your reply, I found this small board on ebay, do you think
that it can be usable directly?
http://cgi.ebay.it/Relay-Board-1-Relay-module-for-AVR-PIC-Arduino-12V-/2...

I need to send command to linear actuator which work at 12v max 5 A

Thanks again

That will work perfectly.