switching 12v fan

Forum 2005-2010 (read only) Hardware Interfacing
1

Hi there,

I need to switch a 12vdc fan/ light, ect. I got myself a ULN2803A ic, it contains eight darlington transistors, ive been told that i need a buffer chip if arduino doesnt have one build in. Does anybody know more on this? Will this be sufficient to switch the fan or light ?

How does this work with an external powers supply ?

Charl.

2

ive been told that i need a buffer chip

That is your buffer chip.

Assuming the fans take 120mA then you will only be able to use about 4 of the transistors due to power dissipation.

http://www.thebox.myzen.co.uk/Tutorial/Power.html

http://www.thebox.myzen.co.uk/Workshop/Motors_1.html