How create a “parallel” overlay switching system …

Hello users. Newbie here.

Several years ago I installed a drip system in my large back yard using 8 valves and a different brand of timer and app. It basically worked, but I didn’t like the interface and eventually ignored/forgot the system because I’m always out there anyway and I started just setting a hose with a mechanical timer on each faucet (I have several of these around the yard now.) But it won’t accommodate my leaving on vacation, so now I want to “modernize” my system without losing the benefits of my “manual” system. I just purchased an OpenSprinkler timer (haven’t installed it yet, Order #79182), but I’m pretty handy and want to simultaneously add a “parallel” system for casual walk-up use. I say “parallel” because it would exist independently of my OpenSprinkler controller, but in the same outdoor case and using the same 24Vac always-plugged-in power source and same zone valves. Let me explain.

First I want simple on-off switches for each zone, so I could walk up, after noticing a zone that needs more water, flip a switch, putter around in another part of the garden for five or ten minutes, and then come flip it off. This seems easy – just a toggle switch (for each zone) between the main power and each valve. I’m not a hardware hacker, but I can do that.

The part I *don’t* know how to do is add a similar *mini timer* (either dial or push-button-to-increment) for each zone to start and run immediately and for only that long. My problem is choosing a not-too-expensive timer switch for this purpose (again, separate from my OpenSprinkler timer, “overlaid” onto the same valve hardware).

Ideally, there exists a mini pcb that can switch 24Vac for a varying amount of time, perhaps by dialing a trimpot or just pressing a mini button that would add increments (of perhaps five minutes each press). I wanted to see if any of you people had an idea for this. I’m willing to spend a bit to get this “overlay” parallel system, but am looking for a clever, easily wire-able solution (doesn’t involve programming, allows walk-up minimal-interaction use). Thanks for even reading this. Any ideas?

-Craig in Fairfield CA
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