Originally posted by Entropy 555 timer IC - Wikipedia, the free encyclopedia
555 + 2.5mm to 3.5mm stereo adapter + cannibalized 3.5mm headphone extension cable + a few transistors and capacitors = build your own intervalometer.
Or if you want to get really fancy, use a PIC or an AVR.
Hello, Having built many 555 projects when I was younger I'd say you over simplified a bit. When a 555 is wired as an oscillator it is difficult to have a wide range of frequency adjustment without switching a lot of capacitors. It is difficult to get long (minutes) periods that are stable. It is difficult to get separate on (exposure) and off (interval) times. It is difficult to select delay before starting intervals. All these features are found in the digital timers listed in this thread.
That said, the timer I use does get a fixed 1 second clock from 555s. To get selectable long intervals the oscillator is divided down by a CMOS counter. There are two cross coupled timers, one for on time and one for off. Still, with the many parts needed, I don't have the initial delay feature.
I suspect most people on this forum are not into designing and building electronic projects as I've done for 50 years.