Has anyone seen a tiny 24VAC inverter?

[fastline]

To clarify my needs, we have an irrigation controller that needs 24VAC. All the internal electrics in it are DC, they normally run on a 24VAC walwart and that power is what is switched and sent into the field to run solenoids and they are not rated for DC operation. I would like to have this controller as a stand alone without grid power, so I am trying to decide how I want to approach it. If I can provide 24VAC to the controller, I can just hard wire it and it's done, but I would have to install a small battery to run the inverter at night, or I guess I could rely on the DC back up battery (9V) for that, but holding constant 24VAC might be simple and reliable.

Other option is I could use a 120VAC inverter and then use the walwart on it.

The way these work is the internal clock and circuit works as normal with just the 9V battery, but without a 24VAC source, it just has no power to a switch to send to the field to power valves.

 

[sunshine_eggo]

24VAC DC/AC power inverter with 12VDC input, how to convert 12 volts dc to 24 volts ac, 40 watts

low voltage 40 watt inverter, 12VDC to 24VAC inverter for CCTV, security, irrigation and other low voltage applications, 40VA

www.powerstream.com

 

[fastline]

I did spot that one, but literally about the only decent one I could find. I wasn't sure if this was a highly special market area?

 

[v_green57]

How many stations?

If you can afford it, replace the AC clock with a DC "solar" one. These use highly efficient latching DC solenoids that need only a "pulse" to trigger them from OFF to ON and back. The rest of the time that the valve is ON it draws no current.

Traditional 24VAC solenoids need 700mA for the duration of the valve being in the ON state.

Google will find them.

BTW: Plain vanilla 24VAC solenoids run fine off of 12VDC if you feel like hacking the clock and replacing the AC TRIACS with FETs.

 

[pollenface]

I have a "24vac power supply" to run my irrigation latching soldenoids. It runs from the same inverter as everything else.

Lookup 24vac power supply on ebay or Amazon. I do plan to upgrade to a proper multi-station irrigation controller one day.

Some 24vac solenoids will run from 12vdc, some won't. Just have to experiment.

 

[fastline]

How many stations?

If you can afford it, replace the AC clock with a DC "solar" one. These use highly efficient latching DC solenoids that need only a "pulse" to trigger them from OFF to ON and back. The rest of the time that the valve is ON it draws no current.

Traditional 24VAC solenoids need 700mA for the duration of the valve being in the ON state.

Google will find them.

BTW: Plain vanilla 24VAC solenoids run fine off of 12VDC if you feel like hacking the clock and replacing the AC TRIACS with FETs.

We will probably have to make do for the moment but I am curious about the latching DC solenoids? Been around irrigation for decades but can't say I've seen this. Our current AC solenoids are 200mA, 4.8W after inrush.

 

[v_green57]

Found these right away:

DC Irrigation Valves & Systems - DIG Corporation

DIG's heavy duty Irrigation Valves are use 6-12 VDC two-way magnetic latching solenoid to activate and operates a ¾” to 2” valves for a wide range of irrigation applications.

www.digcorp.com

but I seem to remember others from the big boys like Hunter, etc. Will keep looking.

The 700mA AC figure I quoted was for the old school Richdel valves, which are most of what I see.

Somebody was also making a current-efficient AC solenoid that used a series capacitor and the inductance of the solenoid itself to create a resonant L-C ckt. that needed very little power. I hate those because you can't use a DVM to check for valve continuity at the clock. Troubleshooting becomes a bitch.

 

[v_green57]

Hunter latching solenoids:

Solenoids

For maximum protection against water intrusion, the 24 V Hunter AC Solenoid features an encapsulated design that completely seals the electronic components in heavy-duty plastic. The captured plunger simplifies servicing by reducing the risk of lost internal parts.

www.hunterindustries.com

(scroll down a bit)

RainBird has 'em too, but they are gawdafully expensive.

Hadn't seen these before:

https://www.amazon.com/dp/B00ES8NSLI

No-name cheap DC valve.