Author Topic: New feature: Ask Dr. Stupidus!  (Read 28348 times)

seagreen

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Re: New feature: Ask Dr. Stupidus!
« Reply #60 on: February 28, 2012, 04:46:08 PM »
Good question, Zinsula.

I bet the simulation of this circuit shows that it works perfectly!    :o
No double blind testing was used in the making of this post.

zinsula

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Re: New feature: Ask Dr. Stupidus!
« Reply #61 on: February 29, 2012, 07:31:05 AM »
Yes! I tried a DBT simulation, and could not spot any difference in ccs current of both polarities. Everything was dark.

Gen. Dreedle

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Re: New feature: Ask Dr. Stupidus!
« Reply #62 on: February 29, 2012, 08:27:21 PM »
Well, what did you expect!!!!!!!!!!!

Perfect, forever, just like.............oh, never mind.
"Major Danby, sir."
"Danby. D-A-N-B-Y."
"Take him out and shoot him."
"Sir?"
"I said take him out and shoot him. Can't you hear?"

seagreen

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Re: New feature: Ask Dr. Stupidus!
« Reply #63 on: March 01, 2012, 04:50:22 PM »
Just ask a simpleton...
No double blind testing was used in the making of this post.

Gen. Dreedle

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Re: New feature: Ask Dr. Stupidus!
« Reply #64 on: July 09, 2012, 02:34:07 AM »
Dr. Stupidus,

found nice feature for this site. Can we incorporate this Country counter into our forum?

Dear Dr. Stupidus,

What do you think the 7 readers from Japan think, when they read this site?

Thank you.


Dear "you",

I am not sure, but it might go something like this:

"How the hell did they ever manage to win the war?"

Quote
Since we beat back them sneaky Japanese.
In the War of 1812.
"Major Danby, sir."
"Danby. D-A-N-B-Y."
"Take him out and shoot him."
"Sir?"
"I said take him out and shoot him. Can't you hear?"

MystereoN

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Re: New feature: Ask Dr. Stupidus!
« Reply #65 on: July 09, 2012, 08:51:16 AM »
I am more impressed with our visitors coming from Vietnam and Iran. Obviously we manage somehow to slip under their CENSORSHIP
Never argue with a fool,
they will drag you down to their level,
then beat you with their experience!!!

seagreen

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Re: New feature: Ask Dr. Stupidus!
« Reply #66 on: July 20, 2012, 02:38:37 PM »
Dear Dr. Stupidus,

What happens when your power supply regulator becomes more complicated than your entire amplifier?  If the impedance is too low, does that suck all the electrons into some kind of alternate universe?
No double blind testing was used in the making of this post.

zinsula

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Re: New feature: Ask Dr. Stupidus!
« Reply #67 on: July 30, 2012, 03:32:39 PM »
Dear Dr. Stupidus

Here i learn from a member which usually knows all at that other place, than an inductor has only an inductance when there is a loop:
http://www.diyaudio.com/forums/analog-line-level/146693-john-curls-blowtorch-preamplifier-part-ii-2525.html#post3109265

BUT, Dr. Stupidus, how on earth is this something special? Don't we want to have loops, in which the current can flow?
Or can we fill the inductor without a loop (as we may do so with a bucket of water) and get the current back the other day?

Gen. Dreedle

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Re: New feature: Ask Dr. Stupidus!
« Reply #68 on: July 31, 2012, 01:38:30 PM »
Dr. Stupidus remembers as a young'un, the chil'run would play something called loop de loop. Is this the loop of which you refer to?

Dr. Stupidus can not remember the nature of this loop, so he used a googling googler to help him. This is what he turned up:

http://www.puzzlesolver.com/puzzle.php?id=48

Dr. Stupidus is now confused, and needs to take a nap.
"Major Danby, sir."
"Danby. D-A-N-B-Y."
"Take him out and shoot him."
"Sir?"
"I said take him out and shoot him. Can't you hear?"

MystereoN

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Re: New feature: Ask Dr. Stupidus!
« Reply #69 on: August 09, 2012, 12:44:16 PM »
Dear Dr. Stupidus, please help my pour soul to solve this puzzle:

We need low noise reference for 5V voltage regulator. TL431 is not very low noise*, but has some advantages:
- low price,
- low dynamic impedance,
- programmable output voltage

OK, lets start with TL431. First we want to increase PSRR and we add CCS in form of cascoded Jfets. Then we start cranking up noise gain (4x) to get 10V reference voltage.
Jfet cascode need some bias voltage across to perform properly, 2 * VGS(off) and TL431 is set to 10V, therefore we need  a lot of headroom voltage. Not to mention, cascode will increase PSRR, but will add noise (compared to single resistor).

Then we start dividing our reference voltage with 10:1 divider to reach 1V. We deploy heavy bulk capacitors and 10K resistor trying to filter out noise, which we increased with our previous steps  :-[

Opamp is then feed with 1V filtered reference voltage, but again we are cranking up opamps noise gain to reach desired output voltage. ::)

And advantages of TL431?
- Is really low price, if we need big capacitors to filter out noise? What about price of capacitors?
- What happens with low impedance if we use 10K resistor in series?
- Do we really need programmable output? Why? To play multiplying/dividing games?

Mamma mia, simulator inside my head is running infinite loops and my head hurts

http://www.diyaudio.com/forums/power-supplies/212476-well-regulated-power-supply.html

* 9000 nVp-p from 0.1 to 10 Hz, see attachment
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zinsula

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Re: New feature: Ask Dr. Stupidus!
« Reply #70 on: August 10, 2012, 05:54:46 AM »
[...]Mamma mia, simulator inside my head is running infinite loops and my head hurts[...]

This situation is similar to the woman who buys all kind of things in the shopping mall, and then looks for discounted products to save the already spent money...
I suggest you sit down an get a beer, and forget about simulator in your head.

Gen. Dreedle

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Re: New feature: Ask Dr. Stupidus!
« Reply #71 on: August 10, 2012, 02:24:25 PM »
Dear Dr. Stupidus, please help my pour soul to solve this puzzle:

..............snip............

Mamma mia, simulator inside my head is running infinite loops and my head hurts

You are making Dr. Stupidus' head hurt. Answering this is above my job grade.

It also seems to be above the job grade of the guy who fantasized it.
"Major Danby, sir."
"Danby. D-A-N-B-Y."
"Take him out and shoot him."
"Sir?"
"I said take him out and shoot him. Can't you hear?"

MystereoN

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Never argue with a fool,
they will drag you down to their level,
then beat you with their experience!!!

seagreen

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Re: New feature: Ask Dr. Stupidus!
« Reply #73 on: February 12, 2014, 07:06:15 PM »
Know the truly bewildering/maddening/sad/hilarious part?

A lot of the people in that thread, and elsewhere, who espouse that sort of thinking are employed as electrical engineers.  Most, but admittedly not all, of the stuff you read in these discussions applies just as much to other electronic areas outside of audio.  So, how do they do their regular jobs??

I respect guys who say something like, "Well, I tried this and that, and I sure couldn't hear any difference!  Maybe somebody else can, but not me!"

That's not the usual stance, though, is it?

Oh.  Well. 
No double blind testing was used in the making of this post.

Gen. Dreedle

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Re: New feature: Ask Dr. Stupidus!
« Reply #74 on: February 13, 2014, 12:58:23 AM »
1.) Only one guy has figured out that rise/fall time might affect jitter. So, he has a clue. The rest are clueless.

2.) Yes, something with a 50 nSec rise/fall time will sound a lot different that something with a 2 nSec rise/fall time. I don't need to write a thesis about it. I could care less what some ponce thinks, but he is wrong.

3.) They refer to Howard Johnson, but they really don't get it. Using him to bolster a narrow-minded, pig-headed, and wrong stance, is a disgrace to a really sharp guy.

4.) Someone needs to tell the o/p there is a thread, over on Greaser's Palace, that shows how to make a TDR. Much easier than futzing with eye patterns, especially if he wants to know why the cable sounds different. Not saying eye patterns are not useful. Just the wrong tool for evaluating a cable.

I still do a limited amount of consulting. Some high-end weenie wants to show why a glass fiber TOSLINK is better than a cheap "fat fiber" plastic TOSLINK.

No.................

Think about this..............

I don't know what the chromatic dispersion is, of either single-mode fiber, or plastic, TOSLINK cables. And you know what? Who cares!!!!!!!!!!!!!!!

Its BW is going to be much more than the rise/fall time of the crappy HC family CMOS crap, that is after the photodiode, will do. Since -3 dB BW = 0.35/tr............well, you figure it out.

(The Sharp datasheet I have shows max rise time is.....................23 nSec. I rest my point.)
"Major Danby, sir."
"Danby. D-A-N-B-Y."
"Take him out and shoot him."
"Sir?"
"I said take him out and shoot him. Can't you hear?"