Robert Tyabji, Shah Alam, December 2011

When we moved into our house in Shah Alam, at the end of 2004, only wild lalangi grasses and a few young trees grew on the northern and eastern slopes of the garden.

Since then, we have planted hundreds of shrubs and other plants, and some trees, which have turned the slope into a veritable forest. Initially, I had to instal drip irrigation throughout the garden, but once the plants took, I turned the irrigation off and the usual bi-yearly rainfall has been sufficient to keep our plants healthy.

It is, however, still necessary to occasionally water the succulents we have planted under the driveway.

To accomplish this, I installed (in December 2011) a Rainbird irrigation valve. This valve, connected to the house water supply, opens when a 24-volt current is supplied to its coil, allowing water to flow. I determined that 2 minutes of water every couple of days would be sufficient to keep the succulents healthy. I decided to build a delay circuit so that all I had to do was press a button every other day to get the water flowing for a couple of minutes each time.

The unit is housed in a waterproof box and utilizes a 555 timer IC. The circuit is shown below.

And so the succulents have flourished!