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The section "Description and construction" describes an Electrolytic Detector. It has nothing to do with a Hot Wire Detector.
And the link to "Electrolytic detector, a development of the barretter detector" is completely wrong.
The two have nothing to do with each other. They use completely different principles.
In fact there is almost nothing in the article which is correct!!!
It claims that "it was invented in 1902 by Reginald Fessenden" and "was the first device used to demodulate audio signals".
(leaving aside that they weren't used to Demodulate "Audio Signals" at all, but used to demodulate AM Radio signals)
Clearly the "Point Contact" and "Carbon" Detectors developed by David Hughes around 1880 could also Demodulate AM transmissions,
even today we use "Crystal Detectors" in our simple AM radios.
The article seems to confuse the action of Coherers (which could not demodulate speech) with other types of Detector (which could).
While Fessenden did develop one of the first low-distortion AM transmitters, Amplitude Modulated signals had been used since the earliest days of radio.
When his first AM signals appeared on the Air, his transmissions could be heard by countless thousands of existing receivers.
Im sure Ive heard of barretters being used as early forms of surge arrestor. Has anyone else? (I could have dreamt it tho'!)-- Light current 02:20, 30 April 2006 (UTC)
No Im pretty sure now that they are!. See ballast (electrical)-- Light current 03:23, 7 June 2006 (UTC)
Yes, the generic Barretter is a universal device which existed long before Radio was invented.
Image:Bareters 085b55 12.jpg is not a hot wire barretter - demodulating detector. This is barretter for electric current stabilization, but not radio frequency demodulation! -- ScAvenger lv 19:48, 8 November 2007 (UTC)
Yes, most definitely.
I might be wrong but ISTR iron wire hydrogen filled barretters being used as constant current devices to stabilise power feed. Tabby ( talk) 10:51, 9 June 2008 (UTC)
Yes. And a Barretter does not need to use Iron (in Hydrogen) as the Filament. These days a Tungsten filament is often used to stabilise current (eg in a simple battery charger).
This page only represents details of Fessenden's original "barretter" patented in 1902 and this is confusing for many people searching for "barretter".
The barretter of Fessenden has little physical resemblance to the popularly known "barretter", mass-produced by GEC, Sylvania and others. Fessenden's Barretter is designed for detecting AM radio signals and the latter "barretter" for stabilizing current. Each device operates in a different mode:
The former: miniaturized geometry, sensitive to the influence of external energy, resulting in a current variation The latter: large geometry, insensitive to external energy, resulting in a stabilised current
Examples of the latter "barretter":
--"Sylvania 4A1 Barretter" http://www.andycowley.com/valves/var/barr/index.html
--Victoria Museum, Stock No. ST 029230 http://museumvictoria.com.au/collections/items/412007/electronic-valve-amperite-regulator-type-4a1-1930-1949
I propose a disambiguation page as so:
There is some more work that needs to be done with the etymology of the word " barretter " . I suspect more people know the popular " barretter " than they know of Fessenden's "Barretter". Akin to the former trademark name " Aspirin " has become 'generic' " aspirin ".-- 86.8.82.197 ( talk) 18:26, 30 April 2012 (UTC)
Or, better yet, how does Barretter look now? Three uses so far. -- Wtshymanski ( talk) 20:04, 1 May 2012 (UTC)
My understanding is that the general term "Barretter" (meaning a Globe with a Positive Temperature Coefficient Filament) long preceded the Radio Detector usage.
In fact to anyone conversant with the art, the Radio Detector was an obvious application of the universal Barretter.
And likewise a Radio Detector could equally use a Negative Temperature Coefficient device. All that is needed to "Detect" is non-linearity.
This article should explain a little more about how the device worked. It sounds like the device is placed in parallel with a base power source and a signal source (the antenna), and increases in signal current cause a resistance drop which permits a much greater (and hence more directly observable) increase in base current. But why doesn't this extra base current in turn cause a further resistance drop, in an exponential run-away (or at least swap to a second equilibrium mode at which the antenna signal gets swamped)?
Is the trick that the signal provides a small perturbative component on a otherwise-constant applied voltage, and that the current (as always) equilibriates according to a function of the total applied voltage, but by exploiting nonlinearity in that function (in this case departing from ohmic linearity due to exagerated thermal effects but remaining monotonic -- or more relevantly its inverse remains monotonic -- on the domain in order to avoid stable bimodality) so the small voltage perturbation can produce a very large purturbation in output current?
Still, I think it is a failing of the article to overemphasise the process that involves the wire becoming hotter, without explaining the complementary process that involves the wire becoming cooler. Cesiumfrog ( talk) 02:52, 13 June 2012 (UTC)
Sorry, but No:
You can get "runaway" with a Negative Temperature Coefficient device (it's then called a "Relaxation Oscillator"), but not with Positive Temp Coefficient, as it's inherently self regulating.
However the non-linearity of the Tungsten filament is key to it's operation. As the Amplitude of the incoming signal varies, it modulates the resistance of the filament.
And because a DC bias current is superimposed, the non-linearity causes an audio signal to be developed in response to the modulation.
However trying to correct anything on Wickipedia is pointless as the "expert" Mods will just revert your contribution.
Late edit: That is exactly what happened. Oshwar came along and deleted it!
You completely missed my point: I didn't claim that ALL Negative Temperature devices will Oscillate, but that you cannot get Oscillations using a POSITIVE Temp Coefficient device.
And how does it matter whether or not a device was commercially used? When did that become relevant?
Fessendon was one of the the first to develop a clean Sinewave (using his high-speed Alternator) and was the first to Voice modulate it, so he gets the credit for the first practical AM TX.
However many had Voice modulated a Carrier before, eg using a Negative Impedance Arc to generate a Sinewave, or even the noisy spark itself.
The claim that the Hot-Wire Detector can identify Arc transmitters is utterly spurious, simply because ALL Square Law detectors can do this.
It is only the Coherer which is different (and then only when it is used to ring a bell).
P.S. Sarkar is one of the worst references. Has been many times discredited. You seem unaware that contemporary Experimenters and Historians are building and testing these devices today and thus have direct experience.
While both the Hot-Wire Detector and the Electrolytic Detector were developed by Fessenden, it is spurious to claim that the development of one led to the development of the other, as the two clearly rely on completely different principles.
And what possible relevance does the reference to the fragile filament have? Almost all of the early Detectors were fragile/delicate and were superseded by later developments.
You're never wrong are you? Would it hurt you so very much to acknowledge your errors, and perhaps even make corrections?
P.S. I've long given up trying to correct Wickipedia errors, all I try to do is put corrections on the talk page so those who care have pointers to their research.
![]() | This article is rated Start-class on Wikipedia's
content assessment scale. It is of interest to the following WikiProjects: | ||||||||||
|
The section "Description and construction" describes an Electrolytic Detector. It has nothing to do with a Hot Wire Detector.
And the link to "Electrolytic detector, a development of the barretter detector" is completely wrong.
The two have nothing to do with each other. They use completely different principles.
In fact there is almost nothing in the article which is correct!!!
It claims that "it was invented in 1902 by Reginald Fessenden" and "was the first device used to demodulate audio signals".
(leaving aside that they weren't used to Demodulate "Audio Signals" at all, but used to demodulate AM Radio signals)
Clearly the "Point Contact" and "Carbon" Detectors developed by David Hughes around 1880 could also Demodulate AM transmissions,
even today we use "Crystal Detectors" in our simple AM radios.
The article seems to confuse the action of Coherers (which could not demodulate speech) with other types of Detector (which could).
While Fessenden did develop one of the first low-distortion AM transmitters, Amplitude Modulated signals had been used since the earliest days of radio.
When his first AM signals appeared on the Air, his transmissions could be heard by countless thousands of existing receivers.
Im sure Ive heard of barretters being used as early forms of surge arrestor. Has anyone else? (I could have dreamt it tho'!)-- Light current 02:20, 30 April 2006 (UTC)
No Im pretty sure now that they are!. See ballast (electrical)-- Light current 03:23, 7 June 2006 (UTC)
Yes, the generic Barretter is a universal device which existed long before Radio was invented.
Image:Bareters 085b55 12.jpg is not a hot wire barretter - demodulating detector. This is barretter for electric current stabilization, but not radio frequency demodulation! -- ScAvenger lv 19:48, 8 November 2007 (UTC)
Yes, most definitely.
I might be wrong but ISTR iron wire hydrogen filled barretters being used as constant current devices to stabilise power feed. Tabby ( talk) 10:51, 9 June 2008 (UTC)
Yes. And a Barretter does not need to use Iron (in Hydrogen) as the Filament. These days a Tungsten filament is often used to stabilise current (eg in a simple battery charger).
This page only represents details of Fessenden's original "barretter" patented in 1902 and this is confusing for many people searching for "barretter".
The barretter of Fessenden has little physical resemblance to the popularly known "barretter", mass-produced by GEC, Sylvania and others. Fessenden's Barretter is designed for detecting AM radio signals and the latter "barretter" for stabilizing current. Each device operates in a different mode:
The former: miniaturized geometry, sensitive to the influence of external energy, resulting in a current variation The latter: large geometry, insensitive to external energy, resulting in a stabilised current
Examples of the latter "barretter":
--"Sylvania 4A1 Barretter" http://www.andycowley.com/valves/var/barr/index.html
--Victoria Museum, Stock No. ST 029230 http://museumvictoria.com.au/collections/items/412007/electronic-valve-amperite-regulator-type-4a1-1930-1949
I propose a disambiguation page as so:
There is some more work that needs to be done with the etymology of the word " barretter " . I suspect more people know the popular " barretter " than they know of Fessenden's "Barretter". Akin to the former trademark name " Aspirin " has become 'generic' " aspirin ".-- 86.8.82.197 ( talk) 18:26, 30 April 2012 (UTC)
Or, better yet, how does Barretter look now? Three uses so far. -- Wtshymanski ( talk) 20:04, 1 May 2012 (UTC)
My understanding is that the general term "Barretter" (meaning a Globe with a Positive Temperature Coefficient Filament) long preceded the Radio Detector usage.
In fact to anyone conversant with the art, the Radio Detector was an obvious application of the universal Barretter.
And likewise a Radio Detector could equally use a Negative Temperature Coefficient device. All that is needed to "Detect" is non-linearity.
This article should explain a little more about how the device worked. It sounds like the device is placed in parallel with a base power source and a signal source (the antenna), and increases in signal current cause a resistance drop which permits a much greater (and hence more directly observable) increase in base current. But why doesn't this extra base current in turn cause a further resistance drop, in an exponential run-away (or at least swap to a second equilibrium mode at which the antenna signal gets swamped)?
Is the trick that the signal provides a small perturbative component on a otherwise-constant applied voltage, and that the current (as always) equilibriates according to a function of the total applied voltage, but by exploiting nonlinearity in that function (in this case departing from ohmic linearity due to exagerated thermal effects but remaining monotonic -- or more relevantly its inverse remains monotonic -- on the domain in order to avoid stable bimodality) so the small voltage perturbation can produce a very large purturbation in output current?
Still, I think it is a failing of the article to overemphasise the process that involves the wire becoming hotter, without explaining the complementary process that involves the wire becoming cooler. Cesiumfrog ( talk) 02:52, 13 June 2012 (UTC)
Sorry, but No:
You can get "runaway" with a Negative Temperature Coefficient device (it's then called a "Relaxation Oscillator"), but not with Positive Temp Coefficient, as it's inherently self regulating.
However the non-linearity of the Tungsten filament is key to it's operation. As the Amplitude of the incoming signal varies, it modulates the resistance of the filament.
And because a DC bias current is superimposed, the non-linearity causes an audio signal to be developed in response to the modulation.
However trying to correct anything on Wickipedia is pointless as the "expert" Mods will just revert your contribution.
Late edit: That is exactly what happened. Oshwar came along and deleted it!
You completely missed my point: I didn't claim that ALL Negative Temperature devices will Oscillate, but that you cannot get Oscillations using a POSITIVE Temp Coefficient device.
And how does it matter whether or not a device was commercially used? When did that become relevant?
Fessendon was one of the the first to develop a clean Sinewave (using his high-speed Alternator) and was the first to Voice modulate it, so he gets the credit for the first practical AM TX.
However many had Voice modulated a Carrier before, eg using a Negative Impedance Arc to generate a Sinewave, or even the noisy spark itself.
The claim that the Hot-Wire Detector can identify Arc transmitters is utterly spurious, simply because ALL Square Law detectors can do this.
It is only the Coherer which is different (and then only when it is used to ring a bell).
P.S. Sarkar is one of the worst references. Has been many times discredited. You seem unaware that contemporary Experimenters and Historians are building and testing these devices today and thus have direct experience.
While both the Hot-Wire Detector and the Electrolytic Detector were developed by Fessenden, it is spurious to claim that the development of one led to the development of the other, as the two clearly rely on completely different principles.
And what possible relevance does the reference to the fragile filament have? Almost all of the early Detectors were fragile/delicate and were superseded by later developments.
You're never wrong are you? Would it hurt you so very much to acknowledge your errors, and perhaps even make corrections?
P.S. I've long given up trying to correct Wickipedia errors, all I try to do is put corrections on the talk page so those who care have pointers to their research.