On Dec 30, 2:07 pm, flipper wrote:
On Tue, 30 Dec 2008 18:36:01 -0000, "Jim Gregory"
wrote:
"flipper" wrote in message
.. .
On Mon, 29 Dec 2008 10:44:56 +0200, "RealInfo"
wrote:
Hi all
I am looking for old tubes operating on very low voltage , battery voltage
.
I need them for portabe batery oerated tube preamps .
Any sugestions ?
Thanks
EC
http://www.duntemann.com/12vtubes/12vtubesindex.htm
12V is a lay, 'slang' term. It's actually nearer 14.3V DC.
Jim
Good luck on finding a 'non lay', 'non slang' datasheet that calls a 6
cell lead acid battery anything other than a 12V battery.
12V is nominal voltage and dern close to actual at 50% capacity. At
full charge a "12V" lead acid will be around 12.7V and 10.5V when
discharged.
14.3V would be charging voltage.
The aircraft industry calls the 6 cell lead acid battery electrical
system, with an autoderivative (i.e., automotive with a FAA-PMA tag:
the alternator is $50 and the tag $450) alternator and a lead acid
battery that differs from lawn tractor only in having check ball caps,
"14V". The alternative is the 28V system which may use a 12 cell lead
acid battery or a nicad with somewhat more cells. The aircraft 14 and
28 volt systems have precisely the same usable ranges as the
automotive 12V and 24V (military vehicles and some older trucks and
buses have 24V) systems.
Bogey voltages for tubes are 6.3 and 12.6 volts which was said to be
a good midpoint in those days.
6 volt systems (never used in aircraft AFAIK) are often converted to
8 volt with a four cell battery. The six volt light bulbs glow
brightly, live not so long, but most old cars don't drive that much
anyway. If you have a 6 volt radio in the car what's the fix? A
dropping resistor I guess.