Multi Valve Liquid Filling Station

[mcasey]

I would like to build a liquid filling station that operates like this:

Master switch should open all valves when tuned on.
Momentary switches should turn only open one valve when pressed.

Idea is to fill 6 jugs with liquid to almost full level. Then use the momentary switches to "top off" individual jugs to precise level.

Can this be accomplished using simple switches? How would I wire this up?

 

[dave9]

Yes, wire the grounds of all solenoid valves together and to the PSU ground.

Next run PSU positive to the master switch then through a wire and a diode in series to each of the valves positive contact, a separate wire and series diode for each solenoid. The diode anode facing the PSU side and the diode cathode facing the solenoid side. The diodes will keep the power from back feeding when the momentary switches are used instead.

You will need to make sure the resultant voltage drop after a diode is still enough to operate the solenoid, but odds are high it is and you could pick a schottky diode for a lower forward voltage drop instead of silicone diode if the voltage is low enough that a schottky is available/affordable in the needed capacity. Depending on how much current the solenoids use, you might also need to heatsink the diodes.

Next run PSU positive to each momentary switch and then from the momentary switch to its individual solenoid.

 

[mcasey]

Perfect! Thank you!

 

[mcasey]

Solenoid spec:
12V320 mA

 

[dave9]

Yes schottky diodes are readily available at a fair margin above those specs, and no heatsinking needed for 320mA... I'd get something rated for at least 1A current or a little more, probably won't cost but a few pennies more than something rated for 0.5A, mostly swamped by postage.

Example: https://www.ebay.com/itm/1N5822-Dio...ottky-Diode-US-Seller-US-Shipper/182816892166