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 http://rayshobby.net/ 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.

4 comments:

  1. I have had no luck controlling a water valve solenoid. See http://dicks-raspberry-pi.blogspot.com/
    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?

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    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. :)

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  2. Ray has since come out with a version that controls this valve,
    http://rayshobby.net/cart/osbeeshield in case you are not done yet.

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  3. Impressive product. Keep sharing more interesting product like this.

    Thank you!

    dust collector solenoid valve

    ReplyDelete