and created his two alternating 500 Hz square waves with a 555 timer and a 74HC74D dual flip-flop. Unfortunately, he didn’t have the time to get a custom PCB made before Santa’s big night.

And of course, if an ATtiny was used, there should have simply been a 555 timer ... circuits. This comes at a great cost, however. The 555 chips take up an unnecessarily large area on the PCB ...