Even today, for some applications it is hard to beat the ubiquitous 555 timer IC. It is cheap ... one or two transistors, a flip flop and an inverter. The idea is you use a capacitor to charge ...

Instead of going with a microcontroller he built the circuit around a 555 timer. What he really needed in this case is a flip-flop but lacking a chip for that he went with the 555 because it has ...

Figure 4 and 5 represent the transistor level schematic that show how a typical asynchronous RESET type flip-flop can be converted into the proposed circuit which can function as either RESET or SET ...