Guys, here's a stupid idea! I've got most of the bits to make a Morgan Jones
headphone valve amp apart from the mains transformer and choke...so after a
couple of glasses of wine I got thinking. The current consumption isn't
going to be too great (how do you work out the current consumption of a
valve?)...what about 24 PP3 9v batteries in series to give me a clean 216V
DC HT. And a wall wart to run the heaters?

Will

"Will Reeve" wrote
Guys, here's a stupid idea! I've got most of the bits to make a Morgan Jones headphone valve amp apart from the mains
transformer and choke...so after a couple of glasses of wine I got thinking. The current consumption isn't going to be too great
(how do you work out the current consumption of a valve?)...what about 24 PP3 9v batteries in series to give me a clean 216V DC
HT. And a wall wart to run the heaters?

Will

Well back in the olden days, portable valve radio sets used HT batteries
like modern ones use low-voltage batteries.

I see no reason not to. Better yet, about about a bank of NiCads or equivalent,
because then you don't have to worry about re-buying when they run out.

It might take some ingenuity to add circuitry to charge them _in_situ_
while the amp is not being used for audio.

Otherwise just taken them out a few at a time and charge them in a normal
charger.


Martin
--
M.A.Poyser Tel.: 07967 110890
Manchester, U.K. http://www.fleetie.demon.co.uk

Two things:
1)If you happen to short out the battery you may get some very original
fireworks.
2)There are low voltage tubes designed for batteries - better to use them.
There have been a number of tube designs using batteries, see for example this
linestage http://www.audioasylum.com/forums/ne...sages/115.html
That one uses ECC86, a double triode with ECC88 pinout which was designed for
battery operation. Has a mu of 14
http://www.mif.pg.gda.pl/homepages/f...035/6/6GM8.pdf

=== Andy Evans ===
Visit our Website:- http://www.artsandmedia.com
Audio, music and health pages and interesting links.

On Tue, 21 Dec 2004 20:37:23 +0000, Will Reeve wrote:

Guys, here's a stupid idea! I've got most of the bits to make a Morgan
Jones headphone valve amp apart from the mains transformer and choke...so
after a couple of glasses of wine I got thinking. The current consumption
isn't going to be too great (how do you work out the current consumption
of a valve?)...what about 24 PP3 9v batteries in series to give me a clean
216V DC HT. And a wall wart to run the heaters?


You could get it to work with 6.3v valves by using a lot of batteries for
the HT but if you are going to be tethered by a LV lead, why not use it
to get the HT too?

Many of the valves *intended* for battery operation are designed for low
HT and LT, with relatively low current on both. Typical old "combined HT &
LT" batteries gave 90v HT and 1.5v LT. DL91 (1S4) was a typical output
pentode designed for 90v, with a 1.4v 0.1A heater!

--
Mick
(no M$ software on here... :-) )
Web: http://www.nascom.info
Web: http://projectedsound.tk