Saturday, July 13, 2013

Gotta Know When to Fold 'em

For the past few months, I have burned up a lot of hobby time trying to build an interface to control the Orbit 58874 sprinkler control valve.  These simply connect in-line with standard water hose connectors and cost about $20.  However, they turned out to be quite complicated to control.

The valve connects with two wires.  Sending a 24V pulse in one polarity will cause the valve to latch open.  Sending it in the reserse polarity will cause it to latch closed.  At least in theory.  And, as a wise professor once told me:  "In theory, practice and theory are the same.  But in practice, they sure as hell aren't."

I had a 24V power supply, but it was a little too powerful.  If you leave the valve powered for more than a second, you can burn out the solenoid coil.  After melting one of my H-Bridge motor controllers, burning out several valves, and losing a couple of months, this project was officially no longer fun.

Fortunately, someone else has already gotten this working.  If you are interested in this, check out where you can find interfaces to these valves for Raspberry Pi and Arduino.  I may just break down and buy his OpenSprinklerPi interface.

But now it's time to throw in the towel and move on to other projects.

UPDATE:  I was mistaken about the OpenSprinklerPi.  It will only support standard valves.  That's easy - apply voltage and they turn on.  Stop and they turn off.

So I have returned to this and will be building an entirely new interface board for the sprinklers.  It will probably include an H-Bridge to control output polarity and relays for each sprinkler.


  1. I have had no luck controlling a water valve solenoid. See
    I have a 1/2" valve purchased vrom adafruit. In the same order, I got the NPN transistor and diode they recommend. I searched out diagrams (also shown in my blog).
    When nothing worked, I deconstructed the circuit, replacing the 9v solenoid with an LED-resistor at 3.3v. I swapped poles on the transistor: dead.
    Even at 3.3v the transistor gets too hot to touch. Any ideas?

    1. I see you have found the solution. As I said in my post above, typical solenoids are pretty straight-forward to use. I am trying to use a latching solenoid. Hope to find time this week to build the new design. Maybe the third time will be the charm. :)

  2. Ray has since come out with a version that controls this valve, in case you are not done yet.