Random comments on common errors in technical documents - Page 10

DF96 · 3rd July 2012, 06:36 PM

No contradiction at all. Linearity does not necessarily imply large output, and it does not necessarily require simple proportionality as a constant bias can be involved too. All linearity, in the context of a PSU, means is that if raising the input from 20V to 25V raises the output by 0.5mV (from 12V to 12.0005V) then raising the input to 30V means that the output goes up 1mV to 12.001V.

I think it was your mistaken introduction of 'proportional' which led you astray.

Wavebourn · 3rd July 2012, 06:42 PM

Linear voltage regulator is opposed to the one that uses PWM. But who is well known vendor of chips for PWM regulators? A company with "Linear" in their name.

wahab · 3rd July 2012, 06:44 PM

"Bootstrap" is one of the worse technical terms since it s barely analytical.

Wavebourn · 3rd July 2012, 06:49 PM

What is confusing in bootstrap?

MarcelvdG · 3rd July 2012, 06:50 PM

No, you are confusing linear with affine. When there is a constant bias involved, the system does not comply with the superposition theorem anymore and it is therefore not linear. At least that's what I've been thought at the Delft University of Technology.

Current feedback has at least three different meanings nowadays:
-In the oldest literature that I've read, it meant series feedback at the output, no matter what happens at the input.

-In the book/PhD thesis of Ernst Nordholt it means series feedback at the output and shunt feedback at the input, resulting in an accurate current to current transfer.

-In the context of current feedback op-amps it applies to the exact same feedback configuration as normal voltage feedback (shunt at the output, series at the input), but with an op-amp having a low open-loop input impedance at its negative input.

Osvaldo de Banfield · 3rd July 2012, 06:51 PM

Quote:

Originally Posted by Wavebourn

Linear voltage regulator is opposed to the one that uses PWM. But who is well known vendor of chips for PWM regulators? A company with "Linear" in their name.

And what if I use a quadratic device like a FET or tube? It has some proportionality, but not necessarily linear (equal output measure per equal input measure)

wahab · 3rd July 2012, 06:59 PM

Quote:

Originally Posted by Wavebourn

What is confusing in bootstrap?

It is not analytical ethymologicaly speaking.

"Positive feedback loop" is the right term and it s quite remotely
linked to "bootstrap".

Wavebourn · 3rd July 2012, 07:34 PM

Right, bootstrap is actually a jargon term for specific positive feedback from output of the voltage follower to it's input.

DF96 · 3rd July 2012, 09:42 PM

Quote:

Originally Posted by MarceldvG

No, you are confusing linear with affine.

Possibly. I think UK EEs generally extend 'linear' to include 'affine', as 'affine' is not a word which crops up often on EE courses here. 'Linear' is taken to mean 'no new frequency components in the output'.

Interestingly, the strict definition of linear excludes all sources (e.g. DC PSU, AC oscillators) so may be mathematically correct but perhaps unhelpful?

wahab · 4th July 2012, 10:23 AM

Quote:

Originally Posted by DF96

No contradiction at all. Linearity does not necessarily imply large output, and it does not necessarily require simple proportionality as a constant bias can be involved too. All linearity, in the context of a PSU, means is that if raising the input from 20V to 25V raises the output by 0.5mV (from 12V to 12.0005V) then raising the input to 30V means that the output goes up 1mV to 12.001V.

Linearity of such PSU is not tied to its regulation factor seen from
input to output but to the relation between its voltage reference
and its output.

3rd July 2012, 06:42 PM	#92
Wavebourn diyAudio Member Join Date: Sep 2006 Location: Pleasant Hill, CA	Linear voltage regulator is opposed to the one that uses PWM. But who is well known vendor of chips for PWM regulators? A company with "Linear" in their name. __________________ If I disappear suddenly, that means I finally created a time machine and pushed wrong button that brought me to Stalin's Russia. In any experiment any result is the result. Even if it is negative.

3rd July 2012, 06:49 PM	#94
Wavebourn diyAudio Member Join Date: Sep 2006 Location: Pleasant Hill, CA	What is confusing in bootstrap? __________________ If I disappear suddenly, that means I finally created a time machine and pushed wrong button that brought me to Stalin's Russia. In any experiment any result is the result. Even if it is negative.

3rd July 2012, 07:34 PM	#98
Wavebourn diyAudio Member Join Date: Sep 2006 Location: Pleasant Hill, CA	Right, bootstrap is actually a jargon term for specific positive feedback from output of the voltage follower to it's input. __________________ If I disappear suddenly, that means I finally created a time machine and pushed wrong button that brought me to Stalin's Russia. In any experiment any result is the result. Even if it is negative.

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3rd July 2012, 06:36 PM	#91
DF96 diyAudio Member Join Date: May 2007	No contradiction at all. Linearity does not necessarily imply large output, and it does not necessarily require simple proportionality as a constant bias can be involved too. All linearity, in the context of a PSU, means is that if raising the input from 20V to 25V raises the output by 0.5mV (from 12V to 12.0005V) then raising the input to 30V means that the output goes up 1mV to 12.001V. I think it was your mistaken introduction of 'proportional' which led you astray.

3rd July 2012, 06:44 PM	#93
wahab diyAudio Member Join Date: Nov 2009 Location: algeria/france	"Bootstrap" is one of the worse technical terms since it s barely analytical.

3rd July 2012, 06:50 PM	#95
MarcelvdG diyAudio Member Join Date: Mar 2003 Location: Haarlem, the Netherlands	No, you are confusing linear with affine. When there is a constant bias involved, the system does not comply with the superposition theorem anymore and it is therefore not linear. At least that's what I've been thought at the Delft University of Technology. Current feedback has at least three different meanings nowadays: -In the oldest literature that I've read, it meant series feedback at the output, no matter what happens at the input. -In the book/PhD thesis of Ernst Nordholt it means series feedback at the output and shunt feedback at the input, resulting in an accurate current to current transfer. -In the context of current feedback op-amps it applies to the exact same feedback configuration as normal voltage feedback (shunt at the output, series at the input), but with an op-amp having a low open-loop input impedance at its negative input.

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