An Introduction to Clock Dividers and Psychological Warfare

A while ago, [nsayer] was inspired by a Hackaday post to build one of the most insidious means of psychological warfare. I speak, of course, of the [Lord Vetinari] clock, a clock that ticks at random intervals, but still keeps accurate time. His build, the Crazy Clock, is a small controller board for off-the-shelf clock movements that adds the [Vetinari] feature to any clock by soldering only a few wires.

The Crazy Clock is a pretty simple device consisting of only a 32.768 kHz crystal, a microcontroller, and a few transistors to pulse the movement of a clock mechanism. While psyops is great, it recently occurred to [nsayer] that this device could be used for other build.

Since the output of the Crazy Clock doesn’t necessarily have to be connected to a clock movement, [nsayer] decided to connect a LED, generating a 60Hz flashing light for a phonograph strobe. This is easy with timer prescalers and clock dividers; the original 32.768 kHz signal is divided by 8 to produce a clock that ticks every 4.096 kHz.  Divide that again by 120, and you get 34 2/15. Yes, this is all stuff you learned in fourth grade, and if you’re smarter than a third grader you can eventually whittle a 32.768 kHz clock down to a nice, round, binary number – exactly what you need for computing time.

[nsayer] posted a 240 fps (vertical) video of his Crazy Clock blinking at 60 Hz. You can see that below.

Continue reading “An Introduction to Clock Dividers and Psychological Warfare”