The starter circuit shown in the figure was found in an old European documentation. The circuit makes use of an SCR which is still common and the diac can be of any type.
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...