This circuit was found in a 1970's Radio Electronics. The pulse transformer has a 1: 1 turn ratio. The triac must be in accordance with the controlled load.
This old configuration of an audio amplifier has a push-pull two-transistor output stage. Output...
This is the traditional configuration of na Astable Multivibrator using two NPN ttransistor....
This circuit is from 1987 documentation. The operating system used is not common today, but two...