This microcontroller-based control circuit adjusts the speed of a small permanent-magnet DC motor to one of four speeds as selected by a pair of photosensors. Firas Mohammed Ali Al-Raie.

[fahadshihab], a young tinkerer, shared his circuit design for a simple remote control using 555 timers. Using a 555 calculator, he designed a clock circuit that would run at 11.99 Hz. Two transis… ...