Found in an English publication from the 1980s, this circuit can be built with equivalent transistors such as the BC549. The signal must be applied to an external amplifier.
This circuit is from a 1974 publication, but it can still be easily assembled today with BC548...
This driver for audio signals using the TAA435 integrated circuit was found in Philips 1968...
We found this circuit for old tape recorders in the December 1972 Radio Electronics magazine. The...