In the course of writing an article on the Loftin-White circuit which appeared in Vacuum Tube Valley issue no.6 (Winter 1997), I wanted an actual amplifier to illustrate the article and for testing. While some breadboard models were illustrated in the original 1930 Radio News articles, there were no definitive plans published, and essentially no samples survive. So I created my own, using period components and following "breadboard" wiring practice. The only item not from 1930 is the 25K Ohiohm cathode resistor: even the oak board was a bit of office furniture that my father brought home after a remodeling job in the 1940s. And I did hide new mylar caps inside the old high-voltage filter cans.
The full account is in the VTV article (www.vacuumtube.com): the history of Loftin and White's work, the (non)-acceptance of their design, my own building project, and a complete bibliography of all Loftin & White and related magazine articles from the 1930s.
click here to view the schematic or the original article
Last Updated 8/13/2004 - 10:57 AM EST