We found this circuit in an old documentation for radio amateurs. The circuit uses an analog indicator. The characteristics of the coils are given next to the diagram.
This circuit, obtained from a 1965 magazine, can still be assembled using some modern equivalent...
This linear speed control for DC motors up to about 2 A was found in a 1978 publication. The power...
This circuit is from 2001 documentation, serving to multiplex stereo signals for FM transmitters. The...