This circuit was found in General Electric documentation from 1968. The circuit uses triac from the time as well as transistors that can be replaced by modern equivalents.
This voltage regulator for automotive use was found in a Radio Electronics from the 80s. The Q3...
This circuit uses a transistor as noise source and a 741 IC as amplifier, sourcing a high...
This circuit is from an 80's documentation, applying to ordinary comparators. The source does not...