Connecting a 12v solenoid valve

Forum 2005-2010 (read only) Hardware Interfacing
1

Hi,
I want to control a 12v water solenoid via an Arduino Uno, I can't remember any of the electronics I did at school over 20 years ago, so please put up with my stupid questions.

As I understand it if I use a 12v power supply for the Uno, I can take 12v out of the VIN pin.
The solenoid I want to use says its 12v DC and uses 4.5 Watts, does this mean the solenoid will be drawing 375mA or is my understanding of volts, watts and amps all fubar? Here is the datasheet for the solenoid I was looking at, model pu22001AR.

Bottom line, can I power this solenoid from my Uno without blowing it up? I was going to trigger the solenoid via a 5v circuit and use a signal thru a Darlington transistor to close the 12v circuit to the solenoid. Does this sound right to you clever people?

I guess I would be better off using a quality regulated psu rather than a cheap unregulated one.

2

Don't forget a snubber diode.

3

It's right you can do it with a darlington configuration, and take the 12v signal of the Vin pin, remember to put a protection diode on parallel to the solenoid for preventing backcurrents to the control circuit when switching states! :slight_smile:

The only limitation on the arduino is that you cant drain more than 1A from the source, it´s limited with a protection diode :smiley:

4

Cheers guys, yeah I have a diode sitting here for just that purpose.
Was I correct in thinking the solenoid will draw about 375mA or have I got my maths totally wrong?

I wish I could remember more of my electronics from school......

5

Yeah! P=VI