Found in a Philips publication from the 1970s, this circuit uses a DO040, which is difficult to obtain today. The circuit is powered by 12 V on pins indicated in the diagram.
This circuit was obtained from an English magazine from 1985. The N414 is a complete, not easy to...
Found on Popular Electronics from 1969, this circuit can be implemented with components that are...
This circuit is from a book of transistors from 1954. The transistors are from the time and the...