Arduino Kit Decision


Would someone please help me select the correct Arduino system?

I am trying to pulse 12v dc to 7 solenoids. I have a controller that outputs 12v dc when humidity and temperature are at a certain level and it stops outputting when the humidity and temperature are not at that level. Whenever the controller changes state from on to off and back on again I need to send a 12v dc pulse to 7 solenoids.

Here is the link to the solenoid

Thanks again for the help.


Hi Jim,

I believe that you would be able to use any Arduino to accomplish this.
An easy board to start with would be the Arduino Uno, part 1050-1041-ND

In order to handle the 12 VDC, you will have to run that voltage through relays that are controlled by the arduino. Based off of the specs for the solenoid, I believe any of these relays are capable of handling them.

Depending on the relay you choose, you may be able to control more than one solenoid with the relay. If my calculations are correct, the solenoid will draw 5.83 Amps when operated, so I narrowed down to relays that are capable of 6 amps or higher current rating.

Are you planning on using all the relays at the same time?

If you plan to use mechanical relays, such as those linked to above, the Arduino will not be capable of driving the relay coils directly. An Arduino I/O pin can only sink or source about 20mA. Most mechanical relays will require much more current than that to energize their coil. For instance, the relays in the link given above require anywhere from 40mA to 178mA to turn them on. Therefore, you will need an intermediate component to take the low current signal from the Arduino and provide the necessary current for the relays.

Here are a few parts capable of taking an Arduino output and converting those into something capable of driving relay coils:


The other thing I would suggest is to make sure you use a relay that is rated somewhat above your assumed load rating. Your solenoid is spec’d for about 6A at 12Vdc. I would make sure the relay you pick is rated for 10A or more for INDUCTIVE loads. This spec is often buried in the datasheet. For instance, the G2R-1A-T DC5 can handle a 10A inductive load as long as the DC voltage does not exceed 20V. So in your case this would be a reasonable choice. However, had it been a 30V solenoid, this relay could only handle a 5A load.

David, manufacturers make relay shields for the Arduino that work on the I/O pins. Also, most models can sink/source 40mA to my knowledge. See my post on compatibility Development Kit Limitations - How to Determine Compatibility .