This circuit is from old American documentation, using a regulator integrated circuit that is uncommon today. The diodes can be 1N4002 and the transformer has a 500mA secondary.
This is the traditional configuration of a 6 or 12 V source with 7806 or 7812 integrated circuits, for a...
This fader or guitar fading circuit was found in an American documentation from the 1980s. The...
Found in documentation from the 1960s, this power supply employs germanium diodes from the time....