This circuit can be used to obtain a zener voltage from a common zener of another value, adjusting in a multimeter. The circuit is from an American documentation of the 1970s.
The critical component of this circuit is the transformer. T1 and T2 can be BD135 and T3 / T4 can...
Found in Popular Electronics from the 90s, this circuit can employ other low power audio...
This circuit is from a 1967 publication. It is possible to power a fluorescent lamp from a 12 V...