This simple 6 V source stabilized by zener diode was found in a European technical publication from 1972, but it is current for its simplicity and the components it uses.
The coil can be formed by 100 turns of 26 or 28 wire on a ferrite rod in this medium wave radio...
This circuit is from a 1968 Electronic Design. The characteristics of the output transformer are not...
This circuit is from a 1970 publication, having been implemented with germanium PNP transistors. We can...