This circuit is from a 1968 Electronic Design. The characteristics of the output transformer are not given and the transistors are of the time. The circuit provides a power of a few watts.
This useful benchtop power supply uses a single LM350 integrated circuit as a regulator. The...
If the input voltage falls below 12 V the LED glows up. Other voltages can be monitored by...
The circuit shown is only for analog telephone lines. I found it in Popular Electronics (1991). It...