This circuit was found in a 1980s documentation. The diodes may be general purpose diodes such as 1N34 or 1N60 and the indicator may be the lowest current range of a multimeter.
This is a dimmer version for incandescent lamps (do not use any other type) from an old...
This circuit is from a factory manual from the 80s. The circuit can be implemented with modern...
We find this circuit in an English 80's documentation. The circuit can be made with more modern...