This 4-transistor amplifier can work from 4.5 or 6 V power supplies. We found it in a Mullard transistors manual from 1960. The transistors are from the time.
The 747 is an old operational amplifier. This configuration suggested in the component manual is...
Suggested by Siliconix in 1980s documentation, this circuit uses currently uncommon components. The...
In the figure we have a circuit to excite a piezoelectric capsule taking advantage of its resonant...