The Supercapacitor

[J M Fahey]

Also, the charge rating for a size D cell ; 10,000 milliamp hours. That would translate into about 10,000 hours service for On time at a constant current draw of 1 mill though a preamp tube gain stage....

Fully agree with the Math.

Me, being a "cheaper is better ... if it does the same" kind of guy, might use 2 1N4002 diodes in series for 1.3V bias voltage or a 1k5 resistor, for exact 1.5V.
Don't know the MTBF life before failure, but I would guess it might surpass those 10000 hours by at least a factor of 10 (and probably *much* more), would weigh from 100 to 500 times less (too tired now to Google) and be 100 to 1000 times cheaper (same excuse).
I almost forgot: would have at least 10 to 100X the shelf life, wouldn't degrade if left in the sun, a humid place, under -20ºC and would support a much higher "G" number.
Of course, my so called "cheap solution" would have absolutely no Mojo at all.

[mooreamps]

Go sit down and think about it for a while.

Well, thinking about it did not take very long... They carry these types of cap's at Haltek in Sunnyvale.. A bias tap from the filament supply would put the bias at the right value. The A/C component of the signal should pass through the cap, although I'm not so sure if that's where the "mojo" is... It just could be the clip was recorded through a really good modeling amp, and the "supercap" is nothing more than a red herring...

-g

[mooreamps]

Most people buy their own or borrow one, instead of asking permission. Or do you admit publicly to working on your private amplifier development using the equipment and supplies of your employer?

Not likely.. Besides, I've had my boss over a few times and well, quite frankly, I'm building hand wired vacuum tube amplifiers, not 460 million dollar space vehicles.. .. :|

-g

[R.G.]

Deleted.

It's just too easy. It gets boring after a while.

[Steve Conner]

You know, I just had a thought. You're a military kind of guy. How does the try-it-first-then-read-about-it approach work with explosives? : - D

I can heartily recommend "Ignition! An informal history of liquid rocket propellants" by John D. Clark. It tells you exactly how that approach works in gruesome detail. It is the only way to make discoveries, because by definition you can't read about something that hasn't been discovered yet.
http://library.sciencemadness.org/li...s/ignition.pdf

My gut feeling is that using supercaps in cathode bias applications would make them explode too.

I am guilty of using my employer's time and resources to build amps, but it's kind of complicated because the R&D lab contains all of the test equipment that used to be in my kitchen. And I'm pretty sure I work at least 40 hours a week on average on what I'm supposed to be doing. Maybe.

[kg]

guys, how do you intend to pass current over the long term through a device that by definition is an open circuit to DC?

[Guitarist]

IN QUICK: Amazing responses, no ?n.
I guess, just repurpose these caps elsewhere, rumour is in a light-weight battery app. N.B. I just take the 9V ( no memory effect type, preferably) apart and always get 100% deliverance so far. Over 300 hrs of playing with up to 2 weeks with no activity. If you rock this rig 1x/month then you suck (more than me
Again, I'm blown away by your insights. I have followed you guys for ages and you all have commented on my embrrassing, non-logical ideas. But note, these little solderable 1.2 volters work great, yielding strong Hi-Fi tones. A smaller cap is rec.

But, scheesh seriously really, I know naught. My Dad said, "If you can capture lightning..." And, by such I've been struck.

[kg]

guitarist: there is a fairly long history of using batteries for tube amps. hence the "b" in b+..

i know that in the hifi circles i used to spend a lot more time in, guys would use batteries in the grid circuits. the advantage of course is that the grid is an open circuit and the battery will last about as long as it would had it been left on the shelf!

obvious advantages: very low impedance, zero ripple, very simple integration (ie no bias winding, crc filter, etc)
disadvantage: non adjustable

i know guys have gone as far as using series stacks of small(er) 12v lead acid batteries for the main b+. similar to the ones you'd see in a UPS. a bunch of those cheap trickle charges on them kept them up during non-listening periods. 20 of those puppies would get you ~300v at some 10 amps of the cleanest, quietest, purest DC you can get!

[Steve Conner]

Well, the thing is, the bias supply was called C-, which suggests it came from a Capacitor.

I'm not disputing the use of rechargeable batteries in the cathode circuit. That made it through all three editions of Morgan Jones's "Valve Amplifiers". But a capacitor isn't the same thing. Like Ken said, it'll just keep on charging up until the tube cuts off.

[R.G.]

I can heartily recommend "Ignition! An informal history of liquid rocket propellants" by John D. Clark. It tells you exactly how that approach works in gruesome detail. It is the only way to make discoveries, because by definition you can't read about something that hasn't been discovered yet.

I'll go give it a look. Yep, there are some things where you have to just gut it up and go try it. For instance, I can't imagine the sheer courage of the first person to try eating okra

I've read that there are some theories about genetics and psychology that have noted that in humans, about 10-15% of adolescent males do not evaluate risks well, and are motivated to go exploring things and places that may are flatly dangerous. It seemed odd that this section of the gene pool would be preserved, as it would logically seem to be self extinguishing over time. 8-( However, upon reflection it seems that these guys are the equivalent of the "stick in the water" to test new environments and food sources. The tribe lost a lot of them, but the few that survived turned up new places to live and new food sources that kept the tribe going and prospering in some cases, often enough to get the "uninformed adventurer" gene preserved. It's an interesting theory.

My gut feeling is that using supercaps in cathode bias applications would make them explode too.

That was mine too, but the quick reading I did says they don't have any catastrophic failure modes, just degradation. Little situations like that are one of the things that make me almost dumbfounded at people who say "We don't need no steenking reading! Let's just go hook it up and try it!" For all the clueless try-it-now kind of guy knows, it could react like an overcharged lithium battery.

guys, how do you intend to pass current over the long term through a device that by definition is an open circuit to DC?

I for sure don't.

[J M Fahey]

To Guitarist's credit, we should remember that after playing "x" hours, we can pop those batteries in an MP3 player and enjoy good music
Not bad, eh?

[Enzo]

And the heater battery was the A, because it came from a... ah... A battery

My folks used to have a portable tube radio in the 1950s. The size of a workman's lunchbox, the bottom half of the thiing was a battery. Big boxy Eveready. it had a four pin socket in the top that a harness from the radio pluged into. It provided heater, high voltage and bias suplies and was indeed called an "ABC" battery.

[777george]

My guitars have active pups. The 9V (or 2 x 9V for 18V)battery lasts a LOOOONG time. A 9v is small, as close to pure DC as is feasible economically. Personally I would try batteries before a supercapacitor. Even size wise the battery could be as small or smaller than the cap. Agree with the above, there is no harm trying an old idea that worked well. My Electar (1937) used a big lantern battery.

Like guitars, buy a lidded battery holder and install. Simple. I have to carry other batteries for guitars JIC. Monitoring battery condition is easy, just listen to your amp.