This circuit was found in a 1980s documentation for amateur radio. The circuit is for 9 MHz signals and values in parentheses for FI of 455 kHz. The circuit can be adapted to other frequencies.
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....