We have some plants outside that can't be reached by our current sprinkler system, and we hand- water them with the hose. What do you do when you go out of town for a couple of days? You first go to Home Depot and buy gadgets. This time its a Melnor "Automatic [Digital] 1 Outlet Water Timer" (SKU 558-026) ($30) and an inexpensive Oscillating Sprinkler (SKU 619-344) ($7). (I already have the hose.)
The timer unit is encased in a sturdy little plastic box, runs off two AA batteries (not supplied) and has an input port that fastens to the faucet and an output port to which the hose fastens. Before installing the unit, however, one programs it - which is a snap, with some simple written instructions. The unit has an LED screen to assist in the programing that is easy to read.
When I first installed the unit, which I had programmed to be "off" but to turn on 15 minutes later for 30 minutes, the water poured through it when I turned on the faucet. The instructions had a "trouble-shooting" chart, and the first thing on it was that problem. The valves, the chart advised, may have come "open" during shipping. Take out the battery holder, wait 30 seconds, and re-install. I did that and then needed to slightly touch up the programming. Back on the faucet it went, and no water ran through. I installed the hose, fastened the sprinkler to the other end, and waited the 15 minutes. Bingo. Problem solved.
The timer is an elegant little work of applied technology. The timer I bought was Melnor's basic digital timer product. It makes more involved ones in its "Aqua-Timer" line.