kruz

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« Reply #20 on: January 31, 2006, 04:35:20 AM »
i've just replyed to yoru email
sorry for the delay :oops:


Samuel Groner

    Zürich, Switzerland
  • Posts: 2935
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« Reply #21 on: March 25, 2006, 02:42:38 PM »
Finally I found time to stuff and test the prototype. Works like a charm! I think Fabio will do a board run, if anyone needs Gerbers let me know and I'll see what I can do.

Within the next weeks I'll write a detailed documentation with parts list, stuffing instructions and application notes. For the time being here a temporary parts list: [removed]

Samuel

mnats

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« Reply #22 on: March 25, 2006, 04:44:50 PM »
Great news! Looks like there will be more DOA building going on in the future.

One question though - what are you using for inductors? I didn't see them on your parts list.

strangeandbouncy

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« Reply #23 on: March 25, 2006, 05:22:33 PM »
Wow!

    another DOA! life just gets better and better . . .


        Wonderful news. ican;t wait yo try.


         ANdyP :thumb:
. . . . RUH ROH . . . . .

Samuel Groner

    Zürich, Switzerland
  • Posts: 2935
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« Reply #24 on: March 26, 2006, 02:55:39 AM »
Quote
What are you using for inductors? I didn't see them on your parts list.

Thanks for pointing this out--completely forgot them. I updated the parts list. Any standard HF inductor with low resistance and reasonable resonance frequency should work in place of the part I indicated.

Samuel

bovox

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« Reply #25 on: March 26, 2006, 10:08:51 AM »
Hey Samuel, I´m not trying to be smart, but you have to take a look
at the M-100 from former NTP in Denmark ( you can find it at Gyraf´s
resources) and tell me what your improvements are?! I can answer one for my self; M-100 runs in class B which I think is a pity because  its a wonderful sounding amp if you not strain it; thats-no heavy load under 5-10kohms.
Cheers, Bo

Samuel Groner

    Zürich, Switzerland
  • Posts: 2935
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« Reply #26 on: March 27, 2006, 01:27:38 AM »
Quote
You have to take a look at the M100 from former NTP in Denmark and tell me what your improvements are!

Perhaps let's say it like this:
* substantially lower voltage noise
* class A drive up to 600 ohm
* input protection
* output short-circuit protection
* improved high-frequency PSRR
* higher open-loop gain (and thus lower distortion)
* lower unity-gain transit frequency (and thus improved stability)

I do not pretend to have any significant invention in my design; it's all about compromises and that's a compromise I like. It is very easy to improve the performance in many respects if you give up the simplicity of these designs and add a few more parts, but that's not what I wanted here.

BTW, I measured the input offset voltage of the first prototype yesterday and found--much to my surprise--that it is below 1 mV. Either I've been lucky or these Toshiba transistors are extremely consistent and SPICE predicts the quiescent conditions very well.

Samuel

Bauman

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« Reply #27 on: March 31, 2006, 02:05:11 PM »
We are about to make some boards of Samuel DOA, check here:

http://www.groupdiy.com/index.php?topic=14712&postdays=0&postorder=asc&start=0

 :guinness:
Fabio
cheers!
Fabio
_____________________
www.thediypill.com/store

Samuel Groner

    Zürich, Switzerland
  • Posts: 2935
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« Reply #28 on: April 13, 2006, 04:13:10 PM »
I uploaded the first revision of the documentation: [removed]

More to come ASAP! Please report errors and typos...

Samuel

[silent:arts]

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« Reply #29 on: April 13, 2006, 05:08:09 PM »
Samuel, great work and documentation, thanks alot.
looking forward to the pcbs :thumb:


tommypiper

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« Reply #30 on: April 13, 2006, 05:46:20 PM »
Very exciting!  Excellent documentation.  Can't wait to see the remaining subjects completed.  Samuel, how can a Swiss write such good English? :grin:
Imagine a wet, slightly chilled from its gas release and decompression, with water droplets condensing, sucking surface tension, slowly sliding down the side, capped by a healthy virgin froth on top..

bovox

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« Reply #31 on: April 25, 2006, 11:34:29 AM »
Hey Samuel, i made a breadboard of this your nice OP,but I have some trouble.
The slew and therefore freq resp. is poor.
I get neg. peak when the square curve goes down, upwards its very slow.
I´ve messured the idle current and they are fine, just as you predicted.
The outp.offset is about 0,8V. The MPSA 18 has about 950 as hfe.
I took away the C2+R8 and it became a figure of 5 better in responce.
I´ve followed your fine desciption but I cant get it work properly.
What to do?
Cheers Bo

Samuel Groner

    Zürich, Switzerland
  • Posts: 2935
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« Reply #32 on: April 25, 2006, 01:15:43 PM »
At which gain/configuration did you test the opamp? Can you measure the voltage drop across R3, R4, R6 and R7 and post them? It looks to me as if one of these resistors could have a wrong value, at least it would explain the large offset and the asymetric slewing.

Removing C2/R8 will of course make the amp unstable at low gains.

Samuel

Samuel Groner

    Zürich, Switzerland
  • Posts: 2935
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« Reply #33 on: April 25, 2006, 03:07:12 PM »
I uploaded the latest revision of the documentation: [removed]

Samuel

bovox

Preview On New Discrete OpAmp
« Reply #34 on: April 25, 2006, 03:18:54 PM »
:oops: -my mistake, I thought I checked evry...
the fault was that the 1k6 never was connected,you pointed me into the right direction. Thanks! So now it reeds 8,2 mV !! offset with gain 1 and 10kohm in the feedback loop. ´This is a fast amp and it reeds square wave above
100kHz but it rings and it could be wise to compensate.
It still has a ringing and an overshot of about 10% mostly on the negative side.  (measured at 10kHz.)
Soon I´m gonna listen to it as well.
Cheers Bo

Samuel Groner

    Zürich, Switzerland
  • Posts: 2935
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« Reply #35 on: April 26, 2006, 01:01:35 AM »
Glad it worked out! Check the simulated impulse responses in the new documentation. With my board and test gear they are pretty close to what I measure.

What happens when you short the 10k feedback resistor? 10k is a bit high in value as it will start to decrease stability together with the rather large capacity of the input transistors.

DC offset should go down as well, I guess.

Samuel

bovox

Preview On New Discrete OpAmp
« Reply #36 on: April 26, 2006, 07:19:20 AM »
Yeh, fine information! I tested shortening the 10k in feedback loop.It
didn´t like that,but when I was around 3kohm it measured really well.
When I came less then 300 ohms it did tend to get nervous. Maybe
cause I´m still in breadboard-land.
Cheers Bo

clintrubber

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« Reply #37 on: April 27, 2006, 12:41:02 PM »
Quote from: "Samuel Groner"
I uploaded the latest revision of the documentation:
SGA-SOA-1_documentation.pdf

Samuel

Thanks, nice to have all the info compiled and as thorough as this.

Samuel Groner

    Zürich, Switzerland
  • Posts: 2935
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« Reply #38 on: May 27, 2006, 03:36:04 AM »
I was able to finish a new revision of the documentation which includes a mic pre circuit in the app notes: [removed]

Samuel

Kit

Preview On New Discrete OpAmp
« Reply #39 on: May 27, 2006, 07:42:55 AM »
Well done!! :thumb:
"Relaxing on the axis of the wheel of life."


 

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