Many swiftlet farmers use the type of digital timers as depicted in the photo. They use them to control when to switch on various equipments such as hygrostats, humidifiers, amplifiers, lights outside the entrance hole to deter owls and so on. It had been my experiences to find that at least the model of digital timer as depicted in the photo is somewhat unreliable as I had came across several such digital timers that I used to control different functions malfunctioned.
It is not a big problem if a farmer has frequent access to the sites of the farms as he or she can replace the faulty items but what if the farmer is far away from the farm and can only visit it periodically due to distance and work commitment? This problem is especially crucial to stand alone farms in plantations or a farm in town hundreds of miles away from where the owners live and work. Imagine if a timer failed to switch on a crucial equipment like the humidifiers for not just a day or two but for weeks or even months especially when the weather is hot and there is no rain during the period?
For the smooth functioning of a system, critical components must be absolutely reliable. Remember the American space shuttle that exploded back in 1987 due to the faulty O-ring? Many of us think of essential electrical equipments in a swiftlet farm in terms of the amplifiers, tweeters, humidifiers or other big or obvious items; perhaps we should also pay attention to smaller items such as digital timers; for as the saying goes, the devil is often in the details.