This configuration similar to many of this site was found in 1965 General Electric documentation. Modern equivalent transistors can be used. LEDs can be used.
This circuit was obtained in a 1975 documentation. The maximum frequency depends on the diodes and the...
Found in a 1990 Hobbyst Handbook this circuit has an output power of a few tens of watts and...
The circuit shown is a constant current source which allows the reading of resistors on a very low...