Found in an Elektor from the 90s, this circuit is based on components that are still common today. Power is supplied with only two batteries.
I got this circuit from an English magazine from 1977. It can still be easily assembled, as the...
Found in documentation from the 1990s, this circuit supports equivalent transistors. The range is on...
We found this circuit in a 1972 RCA technical documentation. The comparator can be any type and C1...