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Using the AD844 as an I/V
Using the AD844 as an I/V
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Old 12th February 2013, 11:53 PM   #221
Eldam is offline Eldam  France
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Maybe first at the left: valve rectifier ? and the dc stopper cap at the right seems to be a mundorf ? the big white with the red is coupling between the i/v valve and the bufer valve ? ... if i remenber a paper on the AMR web or maybe in 6moons...
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Old 13th February 2013, 04:48 AM   #222
AudioLapDance is offline AudioLapDance  Canada
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Back to AD844 common base iv!

AD844/TDA1541A schematic:
AD844 iv TDA1541.png

Hmm, tried to sim the 1541 as a 'current generator' with 10mA DC offset, 2mA. (Is it 10mA sink?) And then cancelled it with a 10mA current sink instead of the little FET circuit from the schematic.


AD844/TDA1541A freq resp
AD844 iv TDA1541 freq resp.png

-3dB @ 100k
63dB gain ?!? Hmmm, that's not right ...?!?

AD844/TDA1541A tina file
ad844 IV TDA1541.zip

Anybody know how to model a current DAC in Tina (better yet TDA1541A and PCM1704!)?

Thanks,
Jeff

Last edited by AudioLapDance; 13th February 2013 at 05:00 AM.
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Old 13th February 2013, 04:51 AM   #223
abraxalito is offline abraxalito  United Kingdom
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Quote:
Originally Posted by AudioLapDance View Post
Anybody know how to model a current DAC in Tina?
I've done it in LTSpice. Never used Tina.
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Old 13th February 2013, 04:54 AM   #224
AudioLapDance is offline AudioLapDance  Canada
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Well don't tease me, post it man!
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Old 13th February 2013, 04:58 AM   #225
abraxalito is offline abraxalito  United Kingdom
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I already did - perhaps you came to the party late

http://www.diyaudio.com/forums/digit...ml#post3328462

The first attachment contains the schematic.
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Old 13th February 2013, 06:36 PM   #226
AudioLapDance is offline AudioLapDance  Canada
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Originally Posted by abraxalito View Post
I already did - perhaps you came to the party late

http://www.diyaudio.com/forums/digit...ml#post3328462

The first attachment contains the schematic.
Whoa! So let me get this straight ... this is a current waveform generator that outputs a copy of the current that actually comes out of a TDA1541A?

Hmmm, not sure how to get your .asc file into Tina


Tried opening it in notepad and renaming it .cir

Keep getting 'error loading library' ...

Helppppppp ...

PS And I changed by 1541 current source Tina model to 2mA offset and 2mA (pk to pk) output. Is that right?

Last edited by AudioLapDance; 13th February 2013 at 06:52 PM.
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Old 13th February 2013, 10:04 PM   #227
jcx is offline jcx  United States
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.asc is the schematic file type, proprietary to LTspice like a CAD .dwg or similar

it really takes ~10 min on a fast connection to be up and running LTspice

you should be able to load the .asc in LTspice then copy the generated Spice netlist to most Spice programs - but you won't have the nice schematic
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Old 13th February 2013, 11:07 PM   #228
abraxalito is offline abraxalito  United Kingdom
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Originally Posted by AudioLapDance View Post
Whoa! So let me get this straight ... this is a current waveform generator that outputs a copy of the current that actually comes out of a TDA1541A?
No - where did that idea come from? Its a current source which reproduces the waveform from a .wav file.
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Old 14th February 2013, 01:30 AM   #229
AudioLapDance is offline AudioLapDance  Canada
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That sounds very cool!

But what I was looking for is a more detailed model of 1541 and 1704 for George.
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Old 14th February 2013, 02:04 AM   #230
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Well its jolly hard to come up with a detailed model for the TDA1541A without knowing the internal schematic. I think perhaps Thorsten knows something about that as he said he got a pile of papers from the original designers. On the 1704 you could start with two R2R networks and switches but it wouldn't get you very far. The primary difference between DACs in terms of sound I reckon is glitch performance and modelling that is very hard indeed.
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