Further text at page 179 and 180 suggests how to calibrate the whole circuit without an oscilloscope. At this point I'm not sure if I want to do this because I don't want to take this project any further by enhancing it or even create a project box.
The video of the different stages of experiment 18 can be found on https://www.youtube.com/watch?v=B5Pbp3wZJUg.
|Overview of the finished circuit.|
|Close-up of the three 555 chips in the middle with on the left the 555 timer that provides the delay.|