We found this circuit in a 1965 Electronic Design. Transistors are still common but admit equivalents for some of them. The circuit drains a current of only 4 mA.
With this circuit it is possible to vary the resistance by adjusting the mark/space reaction of...
This circuit is from a 1967 US publication. The configuration can serve as a basis for designs...
This analog TV circuit can be used on a small transmitter. The circuit is from an 80's American...