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Unsual triode configuration
Unsual triode configuration
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Old 12th October 2019, 12:11 AM   #1
gsantosk8 is offline gsantosk8
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Default Unsual triode configuration

I've studing a SQ decoder for my electrical engineering final term paper and I'm looking for a tube configuration that is analogue to this circuit: Click the image to open in full size. as for the sake of historical contextualization. So, has anyone ever seen a a triode tube operating on this configuration: Click the image to open in full size.

I've heard that some AM radios might use it, but couldn't fine any example, so, if you know, please, tell me a book or a service manual of a radio that uses it.
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Old 12th October 2019, 07:31 AM   #2
ejp is offline ejp  Australia
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You have the series resistor and series capacitor in each other's places, if it matters. It's a cathodyne phase splitter, then a differentiator in one phase, then a summing point where the phases cancel above the Ft (of about 200Hz in the transistor version). So, an integrator? Why did you change these R and C values?
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Old 12th October 2019, 10:01 AM   #3
DF96 is offline DF96  England
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It is an all-pass filter, used where you want to add some phase shift but no variation in frequency response. About the only place I have seen a circuit like that would be a phasing SSB exciter, although there you might have a whole cascade of such circuits.
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Old 13th October 2019, 06:52 AM   #4
PRR is offline PRR  United States
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There was very little excuse to use an All-Pass in days of tubes. Phase is not important enough in audio to spend bottles.

The shining example would be MagnaTone vibrato, in which the fixed resistor is made variable.
https://www.magnatoneamps.com/schema...natone_410.pdf
https://www.magnatoneamps.com/schema...atone_280a.pdf
MagnatoneAmps.com
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Old 22nd October 2019, 04:18 PM   #5
gsantosk8 is offline gsantosk8
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Thank you all, just found out the name of such circuit, it's called Moses' phase shifter. If anyone ever come across this Moses guy, if he's still alive, tell him I'm very thankful.

https://dalmura.com.au/static/Magnat...o%20design.pdf
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Old 22nd October 2019, 04:50 PM   #6
DF96 is offline DF96  England
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I doubt if Mr. Moses invented the circuit, and I have never heard it called a Moses phase shifter. He invented an application for a particular version of it. As I said, it is known as an all-pass filter.
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Old 22nd October 2019, 04:52 PM   #7
Osvaldo de Banfield is offline Osvaldo de Banfield  Argentina
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All pass filters are used to create oscillators, I saw anywhere in the net.
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Old 22nd October 2019, 05:39 PM   #8
gsantosk8 is offline gsantosk8
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Quote:
Originally Posted by DF96 View Post
I doubt if Mr. Moses invented the circuit, and I have never heard it called a Moses phase shifter.
I'm not sure either, I just read the article I posted and it says it's called Moses's phase shift. The point is, all the proffessors who are gonna grade my final paper term ain't much worried about worried about historical accuracy as long as I cite an article as a source, I mean, in case it's wrong, blame whoever wrote it. I truly wish I could find a more reliable source of who 1st invented such circuit, but it's been hard as hell and the only thing I got is this article.
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Old 23rd October 2019, 03:55 AM   #9
PRR is offline PRR  United States
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Quote:
Originally Posted by DF96 View Post
I doubt if Mr. Moses invented the circuit, and I have never heard it called a Moses phase shifter. He invented an application for a particular version of it. As I said, it is known as an all-pass filter.
The passive R-C phase shifter is known from before WWII (sorry I don't have a cite).

I don't recall seeing the cathodyne-driven phase shifter before the 1950s (when Moses wrote); he may have been early in documenting this technique.

It's not in RDH, Shea's fat Amplifier Handbook, or Turner's slim Waveform Measurements.

And Moses 1953 is a fine cite for school-work.
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Old 23rd October 2019, 04:40 AM   #10
trobbins is offline trobbins  Australia
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Yeh, cite the original Moses doc rather than my article - I may get a D- rather than a B+.

Moses used the circuit in a measurement technique - so it was the application of the circuit.

And I think you reached a bit far to say "its called Moses's phase shift" - that was just a brief description for the circuit snip presented in a figure.

Ciao, Tim

PS. you will get an A+ if you can work through the phase shift to be expected from that circuit for particular part values.

Last edited by trobbins; 23rd October 2019 at 04:44 AM.
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