Found in a 1980s documentation, this amplifier uses an integrated circuit that is not easy to obtain now as it is of the era. The circuit is intended for FI ceramic filter circuits.
We found this circuit in a Popular Electronics of the 90s. The circuit still uses light bulbs, but...
This circuit is from Linear Technology 2005 documentation. The circuit is based on company...
The integrated circuit used in this power supply is no longer very common in power supplies today....