A goodly while ago I wrote about the 555 timer.
Just the other day I built my own!
Starting from there… moving through the various stages of assembly…
And it works!
The yellow trace is the output, pink is the charge and threshold (tied together in this case) and the blue is the discharge. The pink is tracing the charge of a capacitor that’s part of the RC timing circuit for this timer.
This is tied to a 9V power supply so as the pink trace discharges to 1/3 of the supply, 3V, the timer is triggered, as it gets up to 2/3 of the supply, 6V, it completes the cycle and the discharge pin in pulled low and discharges the capacitor through a resistor.
The output is a bit noisy, but what the hell… it’s neat to get something, however simple, working away!