This circuit was found I a 1965 Radio Schack documentation. The transistors are from that time, admitting equivalents. The transformer has 500 ohm primary and secondary depending on the speaker.
This circuit was obtained from a 1967 General Electric manual. The circuit uses components of the time,...
This circuit uses an amplifier from National Semiconductor, uncommon nowadays. The numbers in...
This circuit is powered by the source of the equipment under analyze. We found this configuration in a 1974...