Circuit diagrams often show transistors in switching circuits. For an ideal NPN transistor, the switch-on voltage at the base is typically 0.6V (acceptable range is 0.6V to 0.8V).

By comparison, the couple of transistors and a handful of passive components it will take to build out one of these latching circuits will only cost you a couple of cents.

If you’ve ever wanted to dive in and take a look at how memory hardware is implemented here is a good example of how to implement some latching circuits with ether BJT or CMOS transistors. BJ… ...