The circuit presented is a Japanese commercial radio from the 1960s. With a 4.5 V supply, it is a super-heterodyne type with an IF of 455 kHz. 6 germanium transistors are used.
An interesting application that can be implemented with the LM139 is the pulse width modulator. This is...
This circuit converts a positive voltage to negative, with maximum output current of the order of...
This amplifier is suggested by Sanyo and can excite loads of 4 ohms with a power of 4.5 Wrms. The...