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Old 14th December 2012, 07:51 PM   #741
smms73 is offline smms73  Portugal
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Dirk, the spice models that you use in MJE15032c, MJE15033c are from Bob Cordell ?
If they are , is something wrong with the early voltage in those models, it gives better THD than in reality , try to replace with other transistors , and run the simulation again.
Using r10 and r11 with 100m gives good results in simulation but in reality will give bad temperature behavior.
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Old 14th December 2012, 09:47 PM   #742
smms73 is offline smms73  Portugal
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I was not happy with the solution of paralleling 4 board for the es9012 / 9018. I have thought in using a different input for this type of dac , it has less than 500mohms of input impedance, it is biasing at 60ma . what you guys think ?

Q1 and Q2 will be bd139/bd140.


meanwhile i am waiting for the components to arrive to try my test boards.
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Old 14th December 2012, 09:53 PM   #743
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Quote:
Originally Posted by Joachim Gerhard View Post
Try a CCS instead of the zeners.
Those are CCS's... <g>

They are constant current diodes (an fet + resistor in a tiny package).

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Old 14th December 2012, 09:58 PM   #744
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Quote:
Originally Posted by smms73 View Post
Dirk, the spice models that you use in MJE15032c, MJE15033c are from Bob Cordell ?
If they are , is something wrong with the early voltage in those models, it gives better THD than in reality , try to replace with other transistors , and run the simulation again.
Using r10 and r11 with 100m gives good results in simulation but in reality will give bad temperature behavior.
Oh pish pash. You're acting like I'm actually going to build the thing... Nothing could be further from the truth.

I had this power diamond buffer lying around and I got an idea in the middle of the night, "what if I replace the BUF634 with this thing?". I just thought I'd share it for entertainment. I mean, is anyone really considering putting high current TO-220 transistors into an IV converter!??! I'm not...
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Old 14th December 2012, 10:05 PM   #745
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BIB, bigger is better C:
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Old 14th December 2012, 10:09 PM   #746
smms73 is offline smms73  Portugal
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You right Dirk . I need to relax.
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Old 14th December 2012, 11:30 PM   #747
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You right Dirk . I need to relax.
Well, my original power diamond buffer had TO-3 output transistors!

Be the first in your country to put TO-3's in your IV converter!

hahaha

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Old 15th December 2012, 12:55 AM   #748
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Hey Dirk,
I think Sergio is working up to TO-3, he's going for TO-126 (BD139/140) first ;-)

Good work Sergio!
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Old 15th December 2012, 01:01 AM   #749
Shinja is offline Shinja  Japan
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hi smms
I considered CFP but dismissed.
the CFP itself is 2 stage feedback amplifier, then it has slew rate limit, moreover asymmetrical rise and fall.
I think the charactaristics are not suitable for our application.
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Old 15th December 2012, 01:57 AM   #750
smms73 is offline smms73  Portugal
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Hey Dirk,
I think Sergio is working up to TO-3, he's going for TO-126 (BD139/140) first ;-)

Good work Sergio!
This ess dac are a real challenge , maybe I will need to use some TO-3 in the end
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