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.
This circuit was obtained from a Hands-On Electronics, an American magazine from January 1987. The...
This receiver for listening to the TR-23 phone was manufactured in Japan in the 1960s. The circuit is...
This astable multivibrator with an operational one at the time was found in the National...