This experimental bench source was found in a modern book on tubes. The components used can be easily obtained.
July 2017 - Murata's new NCU series thermistors can now be purchased by Mouser Electronics for...
Quadrature Generator for Transistor and SCR Testing This circuit was found in US 1980s...
This circuit was found in a 2005 Linear Technology documentation. The circuit is based on LTC4213...