Need your help you electronic geeks! probably you Russell(kartman) and Dr.Jim

Go To Last Post
12 posts / 0 new
Author
Message
#1
  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Hey guys

Again need your help you freaks. this time about electronic.

I asked my question here but didn't get a decent answer yet:

 

http://electronics.stackexchange.com/questions/243640/what-are-the-purpose-of-those-resistors-and-capacitors-network-before-the-mic-ja

 

 

"One's value is inherent; money is not inherent"

 

Chuck, you are in my heart!

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 1

What exactly is it that you don't like/understand from the 1st detailed answer?

Einstein was right: "Two things are unlimited: the universe and the human stupidity. But i'm not quite sure about the former..."

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 1

Seems to me that the answer is correct and complete.

 

Jim

Jim Wagner Oregon Research Electronics, Consulting Div. Tangent, OR, USA http://www.orelectronics.net

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 1

Amin, i thought your response 'are you kidding me?' was somewhat disrespectful.

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 1

Maybe I should ask: what is it that you do not understand about that answer?

 

Jim

Jim Wagner Oregon Research Electronics, Consulting Div. Tangent, OR, USA http://www.orelectronics.net

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

DO1THL wrote:

What exactly is it that you don't like/understand from the 1st detailed answer?

Hi Thillo

Thank you for your answer. the things that I don't understand:

1- what is the purpose of R27/R29 and or R28/30? sometimes we use zero ohm resistors as jumper or bridge or other purpose but how about R27/R29? impedance matching?

2- Why take the (presumably limited) battery voltage (VDD) and divide it in HALF to product the "phantom voltage"? Why block the DC with C13/C14 only to re-introduce it with R25/R31?

3- Take a look at R22 and C9 or R35 and C19, What kind of ground is this? it doesn't make sense to me. I have seen this kind of grounding already.

4- Winny said "If you put it into a simulator, what frequency response do you get though the network? With capacitors in series for blocking DC, this should form a high pass filter". is it correct in your opinion? if it's correct, why a High-pass filter? the max frequency for human is 20kHz.

 

A capacitor microphone has a built-in FET. I have used this kind of computer head-set microphones. as I said you need around 200 gain to amplify its signals. in this circuit the gain is low. probably those audio chips(in many cases RealTalk chips) have a built-in amplifier.

 

ka7ehk wrote:

Seems to me that the answer is correct and complete.

 

Jim

Hi Dr

I explained some-things to DO1THL.

Kartman wrote:

Amin, i thought your response 'are you kidding me?' was somewhat disrespectful.

I said "you must be kidding me!" and as far as I know we use this when something is unbelievable or odd and it's for expressing amazement.

Sounds like you Aussie have a different culture except your different and odd accent(maybe I should say language!).cheeky

 

"One's value is inherent; money is not inherent"

 

Chuck, you are in my heart!

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 1

1. probably esd protection and hi-pass filtering.

2. so you have 0V across the capacitor. Read up on X5R dielectric properties. It also prevents clicks I'd suggest.

3. it finds the average virtual 0V.

4. of course it's a hi-pass filter - it blocks DC. It's corner frequency will be low - probably 10 Hz. Together with the low pass filter of the op-amp circuitry, you get a bandpass result.

 

It's a single supply op-amp, so you need a virtual earth. I'd also suggest the RealTek chip has a gain section.

It was pretty obvious that R31/C14 form a hi-pass filter (to me and others it seems) and you express surprise without looking into it? That would set off my FW alarm.

The rule of analog is never have more bandwidth than you actually need.

 

As for the 0R resistors? You'd probably have to ask the designer about that. Might be they needed some test points or they may have expected the change the value in production.

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Russell

You are greatZ! thank you for your answer.

 

About several month ago, I made two amplifier. a snapshot:

 

 

 

One of them with TL-431 and another one with LM-386. that circuit which I made with TL-431 didn't have well quality(unclear output) and that circuit with LM-386 had some noise at output. something like motor-boating. Brrrrrrrrrrrrrrrrrrrrrrrrrrrr...

 

Now I'm thinking to make that circuit which I posted in StackExchange. what's your opinion? I have two reason:

 

1- It's a guaranteed circuit. as you can see some genius at SONY have designed and made this circuit.

2- I think this circuit has a great output. good filtering!

 

I just think it'll need another amplifying stage. any opinion about another stage? what kind of amplifier would help?

 

"One's value is inherent; money is not inherent"

 

Chuck, you are in my heart!

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

How exactly did you build an amplifier with a TL431, which is a shunt voltage regulator?

Einstein was right: "Two things are unlimited: the universe and the human stupidity. But i'm not quite sure about the former..."

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Thillo

Yes, it's a shunt regulator but if you take a look in the TL431's datasheet:

 

http://html.alldatasheet.com/html-pdf/28811/TI/TL431/403/17/TL431.html

 

You will know that you can use it for many applications. for my amplifier I used something like this:

 

 

TL431 has huge gain. totally it's a cool component to me.smiley

 

"One's value is inherent; money is not inherent"

 

Chuck, you are in my heart!

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

The schematic you posted was from foxconn was it not? Where does Sony come into it?
As for 'guaranteed' circuit - you can only hope. What it is that you want? A pre-amp for a condenser microphone? Surely there's a zillion on the web - probably using a couple of transistors.

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Kartman wrote:

The schematic you posted was from foxconn was it not? Where does Sony come into it?

Yes it was but it's the motherboard of Sony VAIO VGN-NW series.

 

 

Probably SONY has designed it and Foxconn is designed and making its PCB.(eye rolling)

Kartman wrote:

As for 'guaranteed' circuit - you can only hope. What it is that you want? A pre-amp for a condenser microphone? Surely there's a zillion on the web - probably using a couple of transistors.

I'm thinking to use for electret microphone. Those transistor based circuits ain't so good to me. BJTs have low gain and I should use several stage and noise is another problem. my TL431 circuit is a combo of BJT and TL431. its output is not enough clear.

That circuit is good as a pre-amp IMO.

"One's value is inherent; money is not inherent"

 

Chuck, you are in my heart!