Found in an Elektor from the 90s, this circuit can be powered directly by the power grid. The circuit uses a rectifying bridge that can be replaced by 4 common diodes.
Originally this circuit is from an English magazine, but I found it in Argentina's Radio Chassis...
Found in a Philips' 1968 documentation, this circuit is slightly different from the previous one. The...
This two-transistor amplifier was obtained from a 1977 Radio Handbook. The configuration is valid...