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I'm using Arduino Uno to operate a latching solenoid irrigation valve by using an H-Bridge to set the polarity of the 12V DC going to the valve. A 500 ms + pulse on a digital output pin turns the valve on and then the polarity is reversed and a 500 ms - pulse turns the valve off.

Now I want to operate multiple valves and rather than using a separate H-bridge for each want to know if I can connect the valves in parallel to the 12V circuit and switch them individually with output from different pins.

It seems this could be done with transistors or a chip. A project I built to switch a non-latching solenoid used a TIP120 Darlington NPN Transistor but that will send current from the emitter to the collector, correct? and I need to be able to have current go in either direction. Is there a way of doing this? Thanks.

Edit to add project description: My current design phase is to irrigate 6 almond trees planted in barrels, with control from soil moisture. The next phase would be to control irrigation, with multiple sensor types, to 270 plots. The "aspirational goal" is to irrigate each tree in an orchard individually so ~ 1,000-10,000 locations so cost and power efficiency are important.

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  • \$\begingroup\$ Since you need to provide current in both directions, you really need something like an H-bridge. What is the problem with using multiple H-bridges, one for each solenoid? Is it a cost problem? I don't see any way of doing it much cheaper. \$\endgroup\$
    – Gerben
    Oct 31, 2019 at 10:08
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    \$\begingroup\$ If you really want to use only one H-bridge you could use relays which are able switch alternating current by default. But wouldn't it be cheaper and smaller to use more H-Bridges. or to use OpAmps for 12 Volts and drive the noninverting input or the inverting input. You probably better ask on the electric engineering channel. \$\endgroup\$
    – Peter Paul Kiefer
    Oct 31, 2019 at 10:10
  • \$\begingroup\$ Cost is a consideration, but the question is at least in part so that I can understand what is possible. Currently, I am using a Digilent Inc HB3 bridge which wasn't super cheap but I didn't have to muck around. I don't think a mechanical relay is a good option for this setup - would a solid state relay work? \$\endgroup\$
    – haresfur
    Oct 31, 2019 at 10:29

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