This circuit was found in a 1970 US publication. Transistors are still common and the circuit can be used as a PWM shield or pulse transmission modulator.
The circuit shown here is a CCO. The frequency here depends on the current through the...
This circuit is from an Electronics World of 1967. The described calculations can be applied to...
This driver for audio signals using the TAA435 integrated circuit was found in Philips 1968...