DC operating AC solenoid

Discussion in 'Irrigation' started by jcom, Jul 18, 2007.

  1. jcom

    jcom LawnSite Senior Member
    Posts: 791

    I ordered a zone expander I saw on this site. While checking it out, I could not get proper voltage through the units. After visiting with the company, I was advised to check for DC voltage. I have 30 on two zones and 35 on two zones of DC voltage. Can I use this expander on my regular AC valves?

    Thank you,

    John
     
  2. Wet_Boots

    Wet_Boots LawnSite Fanatic
    Posts: 48,027

    What controller do you have?
     
  3. jcom

    jcom LawnSite Senior Member
    Posts: 791

    Hunter Pro-C. controller.

    Company says the DC voltage is "full wave" DC and will operate solenoids with no problems.

    John
     
  4. Wet_Boots

    Wet_Boots LawnSite Fanatic
    Posts: 48,027

    I never saw a Hunter putting out DC voltage, but then again I wasn't looking for it. So far as I know the AC transformer doesn't supply any DC, and the controller uses triacs to apply the AC power to the solenoids, and those triacs cannot switch DC power. Are there any earth ground connections involved here?
     
  5. jcom

    jcom LawnSite Senior Member
    Posts: 791

    Hey WB,

    The controller is sending AC to the zone expander and is being converted to full wave DC . (first post).

    Company says this full wave DC will operate valves.

    I was checking to see if anyone had any experience with these units using DC.

    Pretty handy units for expanding with no additional wires if they work.

    John
     
  6. Wet_Boots

    Wet_Boots LawnSite Fanatic
    Posts: 48,027

    I'll have to fire up the old scope, and have a look. It was my understanding that the controllers create their own DC to run their electronics (hence the ability of a backup battery to keep it running) but that the DC didn't go beyond that. But if the 60 Hz AC was rectified into 60 Hz DC, the solenoids might not know the difference. I repeat, is there an earth ground involved?
     
  7. bicmudpuppy

    bicmudpuppy LawnSite Silver Member
    Posts: 2,781

    No way I will get caught up and read all the posts, but this one caught my attention. I have seen Hunter controllers (ICC and SRC) run from 12v marine batteries instead of a transformer and everything functioned properly. I don't know if this info helps, but it can be done.
     
  8. Wet_Boots

    Wet_Boots LawnSite Fanatic
    Posts: 48,027

    Running on DC? Odd. I wonder if they moved beyond triacs to switch the power. Triacs are the 'classic' way to use low-power logic circuits to switch AC power, but they don't switch properly with steady DC, like what a battery provides. I know of some old controllers that used mini-relays, and they could deal with battery power to the valves.
     
  9. Mjtrole

    Mjtrole LawnSite Member
    Posts: 226


    Not gettin' off that easy, this one has interesting written all over it.
     
  10. jcom

    jcom LawnSite Senior Member
    Posts: 791

    No earth ground here, just whatever the AC outlet provides.

    Again, the controller output is 25V AC. Checked at the zone terminals. And then to the encoder side of the expander. The ouput of the encoder is DC and is sent to the decoder and from there to the zone valve wires. One of the encoder wires goes to the common but I cannot use the output of the encoder for a common for other valves. The entire expander system has to be by itself.

    Units seem to be good stuff and I will be able to utilize them once I am sure about not ruining a mess of stuff.

    Thanks for the inputs.

    John
     

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