Author Topic: Cooltron - low voltage tube circuits  (Read 7103 times)

AMZ-FX

  • Member
  • Posts: 294
  • south Louisiana
    • http://www.muzique.com/
Cooltron - low voltage tube circuits
« Reply #20 on: February 02, 2006, 08:19:35 AM »
I've now had a chance to look at the Vox Cooltron pedals....   there is no trick to it.

It is a grounded cathode 12AU7 with the triodes paralleled and an opamp servo providing
a voltage to the grids for bias.   The heater is powered from a 3.3v regulator.  The B+ is 6volts.

The pedal has 4 x AA bateries in it.

The batteries drive the 3.3v regulator which in turn feeds the 6v step-up regulator, that
also generates -6v for the opamps.

regards, Jack
Free Schematics and Projects - http://www.muzique.com/
My Guitar Effects Blog - http://www.muzique.com/news/
Follow me on Twitter - http://twitter.com/#!/AmzFx


clintrubber

  • Member
  • Posts: 5608
  • The Netherlands
    • www.motorbongo.nl
Cooltron - low voltage tube circuits
« Reply #21 on: February 02, 2006, 08:52:00 AM »
Quote from: "AMZ-FX"
I've now had a chance to look at the Vox Cooltron pedals....   there is no trick to it.

It is a grounded cathode 12AU7 with the triodes paralleled and an opamp servo providing
a voltage to the grids for bias.


Any relation to the Aphex-esque (tubessence / reflecte plate) anywhere ?

http://www.pat2pdf.org/patents/pat5450034.pdf

stickjam

  • Member
  • Posts: 309
  • Grand Rapids MI
Cooltron - low voltage tube circuits
« Reply #22 on: February 02, 2006, 09:17:06 AM »
Quote from: "PRR"
(The ideal thing would be to design a smaller more efficient heater-cathode system, but nobody is designing new tubes today.)


Ah, but someone is apparently working on new and reeeeeeeeallly small tubes. Vacuum devices embedded in silicon!  :cool:  I'm not sure if it's progressed beyond theory in to actual working models.  Actually I recall reading a blurb on the technology in some magazine not long ago--maybe Electronic Musician.

--Bob

Gus

  • Member
  • Posts: 3910
  • NJ
Cooltron - low voltage tube circuits
« Reply #23 on: February 02, 2006, 09:48:47 AM »
Thanks for the update Jack

Cold Cathode Field emission using a Si IC is not new IIRC.

 I believe I read about this in a mag in the 70's or 80's.   TI is what I seem to remember.

Maybe Brad or PRR or someone else remembers?

bcarso

  • Member
  • Posts: 4055
  • San Fernando Valley, Los Angeles
Cooltron - low voltage tube circuits
« Reply #24 on: February 02, 2006, 04:10:13 PM »
I vaguely recall that too.  More recently there was quite a lot of work done on arrays of individually addressable point emitters in vacuo for displays.

This reminds me of a guy who stiffed me for about 600 books from the library of a late Prof. who had specialized in field emission...grrrrr

PRR

  • Member
  • Posts: 7450
  • Maine USA
Cooltron - low voltage tube circuits
« Reply #25 on: February 02, 2006, 05:46:56 PM »
> Vacuum devices embedded in silicon!

Yeah yeah, nothing new.

What they have now is lamer than Edison's grey lamp or DeForest's earliest bottles. If this were the only amplifier around, it would take 30 years to get to a 6L6 or 12AX7. We do have other, mature, devices for nearly all applications, so it won't get the big investment. True, displays may drive improvement; but they have been saying that for 40 years and I ain't seen one at BestBuys yet.

And those geometries!!!! A type '10 tube is 100 times better geometry. What they got looks like Plate Input Grid Output abuse of a classic tube, except I'm not sure how the electrons are supposed to know which is which. The field emission types seem to run positive grid. Wonder if they know to check for grid current? Would be hard to notice, since plate current is vanishingly small and the grid would be similar. The one experiment tested enough to interpolate a Mu gives about Mu=3 (lousy geometry).

The "sound" of classic thermionic tubes is really about non-optimum geometry. Not bad geometry, just not intensely well coupled like a crystal junction. Here we have very wacky geometry in a process and scale that can NOT do the wires-and-tabs shape of classic tubes, not to mention that any big money will be in that field emission thing (ripping electrons directly out of a solid) instead of the wastefully gentle Thermionic Emission. FE seems to give a log curve, but I can't tell if it is anything like Child's Law.

If I had to bet between bleeding-edge research, and keeping Russian/Chinese bottle-blowers running, I'd stock-up on tube sockets.

gfr

  • Member
  • Posts: 14
Re: Cooltron - low voltage tube circuits
« Reply #26 on: April 06, 2012, 01:03:41 PM »
Sorry to bump such an ancient thread. But I think we were looking at the wrong patent:

http://www.google.com.br/patents/US7397303?printsec=abstract&dq=korg+tube&ei=khl_T7CQGYnDgAef3MSHCA#v=onepage&q=korg%20tube&f=false

This one matches with the actual schematics. Look at fig. 2, very low plate and filament voltage (4V) and a bias servo built around an opamp.

Funny, this patent is dated 2008, 3 years after the release of the cooltron pedals and the other (inverted mode) patent... Smoke curtain?

mjk

  • Member
  • Posts: 143
  • Eureka, CA
    • Redwood Coast Music and Studio Blade Electronics
Re: Cooltron - low voltage tube circuits
« Reply #27 on: April 06, 2012, 01:44:32 PM »
Patent number: 7397303
Filing date: 3 Nov 2003
Issue date: 8 Jul 2008

gfr

  • Member
  • Posts: 14
Re: Cooltron - low voltage tube circuits
« Reply #28 on: April 06, 2012, 03:30:37 PM »
That'a what I call "pending" :)

mjk

  • Member
  • Posts: 143
  • Eureka, CA
    • Redwood Coast Music and Studio Blade Electronics
Re: Cooltron - low voltage tube circuits
« Reply #29 on: April 09, 2012, 09:27:16 AM »
That'a what I call "pending" :)

I think I have that beat by at least a few months. This patent was applied for in 2006 when I was at Sun Labs and just issued last week:

3.  Michael J Koster, Shailendra Deva, Brian W O'Krafka: Shared cache for point-to-point connected processing nodes. Oracle America Apr, 3 2012: US 8151057


 

Related Topics

  Subject / Started by Replies Last post
5 Replies
1452 Views
Last post August 26, 2004, 06:02:21 PM
by shoreditch reader
1 Replies
1422 Views
Last post October 20, 2004, 02:59:30 AM
by
7 Replies
923 Views
Last post March 06, 2006, 08:07:08 AM
by mikeyB
6 Replies
2098 Views
Last post January 12, 2010, 04:24:02 PM
by JanusRec
4 Replies
527 Views
Last post November 20, 2012, 06:59:25 AM
by manulaudic