This circuit, obtained from a 1965 magazine, can still be assembled using some modern equivalent components. The transistors may be BC558 and the transformer is obtained from a disused transistor radio.
This circuit makes use of a special LM195 power transistor not very easy to obtain. The circuit is from...
The components of this circuit from the 70's are no longer common on the market, but it is...
This circuit was found in an Italian magazine Radiorama from 1960, but it can be assembled with...