Using transistors at the time, this circuit was found in a 1970s documentation. Transistors support modern equivalents for 2A currents at least in the case of the output transistors.
This circuit is from a Popular Electronics from the 90s. The circuit has a tone frequency...
This solar powered circuit was found in a 1991 documentation. The transistor is a general purpose...
This circuit is based on a common cathode 7-segment display. The circuit is based on CMOS...