This circuit is from an article about operations in a Radio Electronics magazine from around 1968. The transistors are types of the time and the power is not the greatest.
This circuit, from the 90's, is intended for operation with vinyl record players of the time, as...
Using a zener diode it is possible to change the linearity of the scale of an analog instrument by...
Found in American documentation from the 1980s, this circuit prolongs the ringing of a doorbell or chime...