This circuit was found in a 1968 documentation. It makes use of both NO and NC reed-switches and small magnets attached to a card in the form that results in the drive combination.
This circuit was found in an American 80's documentation. The transistor is of germanium of the...
This circuit produces a signal in the range corresponding the the VHH channels between 2 and 6....
Using a general-purpose transistor this AC amplifier was found in the November 1993 issue of...