You might expect a microcontroller to show up at this point, but [Matthew] went old school, and created his two alternating 500 Hz square waves with a 555 timer ... having the board in hand ...

Figure 1 The 555 timer test circuit is configured for a low duty cycle. The circuit was built and tested on bread board. It worked well and the customer was pleased, but the academic in me, as well as ...

The 555 timer is a versatile integrated circuit (IC) that can control timing in electronic circuits. It's one of the most widely used ICs due to its reliability and flexibility.

If this important detail is ignored, the timeout period is reduced and inconsistent. This 555 timer circuit resets almost instantly when Vcc drops below +10V. This circuit avoids the use of the 555 ...