What is a "gridless control" tube ?

aldovan · 26th July 2009, 03:12 AM

Friends

What is a "gridless control" tube ?
I read in this article:
" During that November, in an attempt to either replicate his work with the flame detector, or possibly to make his device different from Fleming's, de Forest sought a patent on a device that consisted of a filament, an anode and a control electrode of sorts (not a grid). Such a tube could not have provided de Forest with any useful gain. (However, years later, this principle of “gridless control” was successfully adopted by Heintz & Kaufman Ltd. and was the basis for their “Gammatron” tubes.) "

What is this principle ?

Thanks,

Aldovan

HollowState · 26th July 2009, 05:52 PM

Sounds like you're asking about a thyratron. A three element device (tube) used for control purposes.
http://en.wikipedia.org/wiki/Thyratron

Steerpike · 26th July 2009, 06:02 PM

These could be cold cathode gas-filled diodes, that do not conduct at 'normal' operating voltages. A radiation source - such as gamma rays, or ultra violet light, ionises the gas, making the tube conductive.
These were used for instance as flame failure detectors in furnaces.

Some had an extra 'holding' electrode to maintain the conduction state if the ionising radiation was removed.

Robert McLean · 27th July 2009, 12:41 PM

A gammatron is basically a tube with a cathode and 2 plates.
It was an attempt to get around the DeForest patent for triodes, which uses a grid between the cathode and plate. The gammatron has one plate beside the other. The main current goes from cathode to one plate, and changing the voltage on the other plate will draw away more or less of that main flow of current.

There is an article on the web somewhere about using full wave rectifier tubes at reduced voltages to produce a gammatron effect.
I have never tried it myself.

aldovan · 28th July 2009, 03:39 AM

Robert

Yes, Gammatrons !!!
I use a gammatron 3C24 in audio and sound fine.
See my amplifier:
http://www.youtube.com/watch?v=rcVQkrff6pM
But this gammatrons have grids and is possible the plate current control. But the grid voltage in my application is positive.
Do you have this link for the gammatron effect ?

Thanks,

Aldovan

26th July 2009, 03:12 AM	#1
aldovan diyAudio Member Join Date: Jul 2005 Location: Campo Grande city	What is a "gridless control" tube ? Friends What is a "gridless control" tube ? I read in this article: " During that November, in an attempt to either replicate his work with the flame detector, or possibly to make his device different from Fleming's, de Forest sought a patent on a device that consisted of a filament, an anode and a control electrode of sorts (not a grid). Such a tube could not have provided de Forest with any useful gain. (However, years later, this principle of “gridless control” was successfully adopted by Heintz & Kaufman Ltd. and was the basis for their “Gammatron” tubes.) " What is this principle ? Thanks, Aldovan

26th July 2009, 05:52 PM	#2
HollowState diyAudio Member Join Date: Aug 2006 Location: Taxland, New Jersey	Sounds like you're asking about a thyratron. A three element device (tube) used for control purposes. http://en.wikipedia.org/wiki/Thyratron __________________ "The supercomputer is technologically impossible. It would take all of the water that flows over Niagara Falls to cool the heat generated by the number of vacuum tubes required." ~ Professor of Electrical Engineering, New York University

26th July 2009, 06:02 PM	#3
Steerpike diyAudio Member Join Date: Jan 2006 Location: Johannesburg, South Africa	These could be cold cathode gas-filled diodes, that do not conduct at 'normal' operating voltages. A radiation source - such as gamma rays, or ultra violet light, ionises the gas, making the tube conductive. These were used for instance as flame failure detectors in furnaces. Some had an extra 'holding' electrode to maintain the conduction state if the ionising radiation was removed. __________________ Steerpike's Toybox

27th July 2009, 12:41 PM	#4
Robert McLean diyAudio Member Join Date: May 2005 Location: Stittsville, Ontario, Canada	A gammatron is basically a tube with a cathode and 2 plates. It was an attempt to get around the DeForest patent for triodes, which uses a grid between the cathode and plate. The gammatron has one plate beside the other. The main current goes from cathode to one plate, and changing the voltage on the other plate will draw away more or less of that main flow of current. There is an article on the web somewhere about using full wave rectifier tubes at reduced voltages to produce a gammatron effect. I have never tried it myself. __________________ Robert McLean

28th July 2009, 03:39 AM	#5
aldovan diyAudio Member Join Date: Jul 2005 Location: Campo Grande city	Gammatrons !!! Robert Yes, Gammatrons !!! I use a gammatron 3C24 in audio and sound fine. See my amplifier: http://www.youtube.com/watch?v=rcVQkrff6pM But this gammatrons have grids and is possible the plate current control. But the grid voltage in my application is positive. Do you have this link for the gammatron effect ? Thanks, Aldovan

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)

Thread Tools	Search this Thread
Show Printable Version Email this Page	Search this Thread: Advanced Search

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
What makes an amplifier "bright", "warm", or "neutral"?	JohnS	Solid State	51	13th December 2009 06:42 PM
"sensorless" soldering iron temperature control	star882	Parts	3	24th May 2009 08:44 AM
The "Leap-Frog" Method Of Switching Amplifier Control Loop Design	analogspiceman	Class D	29	1st December 2006 03:21 PM
Is it possible to get "tube sound" with just a tube preamp and chipamp output?	Spasticteapot	Instruments and Amps	43	15th May 2006 05:28 PM
"Start me up..." AlephX with relais control and powermanagement.	joho	Pass Labs	26	22nd December 2005 02:47 PM

New To Site?	Need Help?
Register to Participate Search Privacy Statement Contact Us	Frequently Asked Questions Did you forget your password? Mark Forums Read