Dual is good, but no indirect cathode means you can't USE them like dual matched, except with common-cathode circuits. High voltage is good, but it's not high ENOUGH.
A real dual triode, 6BC8, has transconductance 6200 micromhos, this has 54. The grid capacitances are terribly high, and no plate current to speak of.
The only use for this particular item is to show the concepts of vacuum tubes, not how they can be useful. So, it's more a physics demo widget than a real building block.
You could probably get the most power out by using both sections in push-pull class B. Connect the filaments together and run one leg of a center-tapped output transformer from each with B+ on the center tap.
That way you have maximum output current with minimum plate voltage and vice versa. Each side only "sees" the signal half the time which reduces the average dissipation as well
kind of. You added another amplification stage in silicon - the seller couldn't claim that to be a vacuum state output. I guess they could describe their product as vacuous though.
If the thing could put out enough to drive a headphone it wouldn't need any transistors at all to run off a pc or similar input.
NT
If the current can't change I guess zero.
both at once.
NT
I'm not seeing any need for the supply to be floating. In fact it can't be with a direct heated filament valve.
NT
Next time I'll be sure to draw a little box with "As Yet Unspecified DC Bias System" in all such cathode leads.
that's usable though.
that's ok if it feeds something with high Rin, eg an opamp
no problem at audio, which is the only vaguely sane thing to do with it. 4pF at 20kHz is 2Mohm.
More aimed at the new product pseudo valve sound crew I think. Physics demos could use any old triode at a tenth the price.
NT
You could do that, but why would anyone? They're hopeless as output devices, even in class D.
I don't see why they've limited the anode Pdiss so severely. Normal VFD construction should see permissible Pdiss orders of magnitude greater than 1.7mW.
NT
Ahh, do you work in marketing? :-)
On a sunny day (Fri, 26 May 2017 13:34:56 -0700 (PDT)) it happened snipped-for-privacy@gmail.com wrote in :
We discussed radioactive isotope tube heaters long time ago.
s like:
I think marketing came up with the idea of using tubes, engineering came up with a fix ;)
They're both working to relieve the service department from tech-savvy musicians noticing the 12AX7 (some varieties of which don't have any noticeable glow) in their product is "broken"
Depending on how it is packaged, it might make good electrometer tube.
Regards,
Boris Mohar
Got Knock? - see: Viatrack Printed Circuit Designs (among other things)
void _-void-_ in the obvious place
-- This email has been checked for viruses by Avast antivirus software. https://www.avast.com/antivirus
:) Don't you love newsgroups
NT
My God, it's full of nitpicking engineers!
C
The grid current spec is high. That grid is practically a waffle iron; I'd guess that a good fraction of the emitted electrons hit that huge flat grid structure.
-- John Larkin Highland Technology, Inc lunatic fringe electronics
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