On Tue, 18 Feb 2014 20:00:32 +0000, gareth wrote:

What I find intriguing is the realisation that valves ("tubes" to you?)
can be operated with only 12V on the anode.

You're thinking of the American way to do things. European car
manufacturers were slow to change to 12V electrical systems, so they used
tubes that worked with 6V on the plate. An example is the EF98, http://
http://www.mif.pg.gda.pl/homepages/f...030/e/EF98.pdf.

I've seen data sheets with even lower voltage ratings but I can't put my
finger on one right now.

--
Jim Mueller

To get my real email address, replace wrongname with dadoheadman.
Then replace nospam with fastmail. Lastly, replace com with us.