This circuit was found in a 80s American documentation. The zener diodes determine the points of action of each stage and the transistors can be general purpose types.
This version of the previous circuit uses a common transistor Hartley oscillator for modulation. We found...
This simple power supply is not regulated and the output current depends on the transformer. It...
This circuit was found in a 1992 documentation. It activates a relay when light falls on a...