Intervalometer

This is a simple but practical circuit that can be built and understood by almost anyone. Timer one is built as an astable oscillator. Timer two is built as a one shot(monostable). Timer one sets the interval time of timer two. When timer one goes low at pin 3, it triggers pin 2 of timer 2. One could use potentiometers on each timer to vary the timing of each allowing a wide range of options. One example in which this circuit could be used is in an irrigation system where timer 1 sets the time to water and timer two sets the duration. Another example would be in time lapse photography. Timer one would set when the exposure is taken and timer 2 would set the duration of the exposure. ***Note*** The timing cycle of timer 2 should be shorter than the duty cycle of timer 1 to avoid missing the pulse from timer 1.

published 5 years ago