The $3.00 sprinkler timer


 Projects 3Bucktimer Timer2
John writes –

A few years ago we built a large cover over our back deck, and shortly thereafter put up a few hanging baskets for flowers. Here (in Arizona) the summers are hot enough that you have to water the baskets at least twice a day to keep the flowers alive. The problem: I forget. Miss watering for one day and there are three hanging baskets of dead and dried flowers. Trust me, I’ve got three years of dead daiseys under my belt here, and Lisa doesn’t let me forget it. Obviously we need an automatic sprinkler system.

Hacker’s Bench : The $3.00 Sprinkler Timer – Link.

4 thoughts on “The $3.00 sprinkler timer

  1. saimhe says:

    I always believed that in order to use a LED with AC, a regular diode should be connected in parallel (and backwards, of course) to minimize the reverse voltage. The author does just that in a 24 V circuit, but connects the protection diode serially in a 110 V circuit. Why?

  2. jschuch says:

    Hi Saimhe,

    I’ve always thought the same thing, then I came across this . I didn’t quite get it, but I wired it up and my test circuit ran fine for weeks, and nothing got hot. I like this configuration better because it’s easier to wire it together and stuff the whole thing in a piece of heat-shrink tubing.

    Thanks for the note … Since you made me go look the original schematic up I noticed that I forgot to note that the resistors are 1W. I’ve changed the schematic on the page. Thanks!


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