I haven’t built any sequential logic circuits since electronics school. Back then, a 555 timer was used as a clock source to drive JK flip-flops connected to the address lines of EEPROMS that contained programs I had written in hexadecimal. In a world of super cheap Arduinos, raspberry pi’s, etc. the days of making projects in that manner are long gone, for me anyway. That was really fun stuff though, and I have a bunch of 555 timers in my parts bin. So, I decided to tinker, and see if maybe I got some inspiration.
I built the astable multi-vibrator circuit straight out of the datasheet.

- r1: 100K ohm
- r2: 1M ohm
- c1: 160nF
According the this awesome calculator, I’m running at about 4.3Hz with about a 50% duty cycle, which looks about right.

