Found in old documentation, this circuit makes use of amplifiers of the time, uncommon today. Next to the diagram, the formula for calculating the components.
This is stage is transformer coupled and was found in na old publication of the year 1958. The...
This circuit is from the magazine 73, for radio amateurs, from the 80s. The circuit uses common...
This indicator circuit used and game machines (arcades) to indicate that the machine is being...