This commercial radio with 3 earphone listening transistors was manufactured in Japan in the 1960s. The medium-wave circuit uses germanium transistors and is powered by a 9 V battery.
The interesting circuit shown in the figure, can have its gain digitally controlled and present two...
This circuit that has a response from 10 Hz to 700 kHz was found in Philips documentation from 1968. Dual...
This circuit is from a 1976 Motorola CMOS manual. It can be implemented with modern Darlingtons like...