Current conveyor as a voltage amplifier - Page 25 - diyAudio
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Old 13th April 2013, 05:09 PM   #241
dadod is offline dadod  Croatia
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Quote:
Originally Posted by Telstar View Post
Very nice thread
What's the gain and can you post FFT with 1VAC input, at 20khz?
The gain was set to 7.8(18dB), but here is with the gain set to 3.7 too.
dado
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File Type: jpg GainWire-FFT-20k-1Vp-gain4.jpg (194.7 KB, 399 views)
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Old 13th April 2013, 08:27 PM   #242
Telstar is offline Telstar  Italy
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Looks good, dado.
Did you measure the DC offset? How do you control it?
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Old 14th April 2013, 06:47 AM   #243
dadod is offline dadod  Croatia
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Quote:
Originally Posted by Telstar View Post
Looks good, dado.
Did you measure the DC offset? How do you control it?
As this is not GNFB circuit the DC offset is not zero(or very close) but in my case about 60 - 70mV. I have a trimpots but I used it to set equal source currents(suppose it will set lowest distortion). For me that DC offset is not a problem as my poweramp has input capacitors, but just in case I have other delayed output via capacitors(6.8uF).
Solution for the DC offset could be a servo, but I did not bother.
dado
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Old 14th April 2013, 12:09 PM   #244
Telstar is offline Telstar  Italy
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Quote:
Originally Posted by dadod View Post
As this is not GNFB circuit the DC offset is not zero(or very close) but in my case about 60 - 70mV. I have a trimpots but I used it to set equal source currents(suppose it will set lowest distortion).
I'm pursuing a 0GFB design without servo. For headpnones safety the DC should be less than 5mV, but I believe that a good design and a few accurate trimpots in key points (i.e. not only at the input) should be enough
Time will tell
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Old 14th April 2013, 12:27 PM   #245
dadod is offline dadod  Croatia
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Quote:
Originally Posted by Telstar View Post
I'm pursuing a 0GFB design without servo. For headpnones safety the DC should be less than 5mV, but I believe that a good design and a few accurate trimpots in key points (i.e. not only at the input) should be enough
Time will tell
I use bipolar electolytic capacitors of 100uF to connect 300ohm hedphones.
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Old 15th April 2013, 04:43 PM   #246
dadod is offline dadod  Croatia
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Progress so far.
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File Type: jpg GainWire-4.jpg (494.5 KB, 363 views)
File Type: jpg GainWire-5.jpg (568.5 KB, 331 views)
File Type: jpg Gainwire-6.jpg (512.4 KB, 307 views)
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Old 1st May 2013, 06:50 AM   #247
dadod is offline dadod  Croatia
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Default GainWire-mk2

Here is simpler variant of the current conveyor line amp. It uses only two types of semiconductors, all BJTs are BC550/560 and mosfets are DN2540.
Volume control is after the gain stage(P1) and it has advatage to maintain constant signal/noise ratio over whole volume regulation. It could use similar shunt regulator as GaiWire but with lower voltage and power dissipation.
Damir
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File Type: jpg GainWire-mk2-sch.jpg (123.5 KB, 198 views)
File Type: jpg GainWire-mk2-gain.jpg (227.8 KB, 174 views)
File Type: jpg GainWire-mk2-FFT20k.jpg (184.6 KB, 143 views)
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Old 2nd May 2013, 01:49 PM   #248
dadod is offline dadod  Croatia
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Default GainWire mk3

Or this one.
Damir
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Old 8th August 2013, 05:39 AM   #249
RNMarsh is offline RNMarsh  United States
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Default SIM This --

What can you guys do with this? SIM it and add what is needed for output stage etc.

It uses cancellation technique to reduce distortion. [I'm into cancellation circuits now]

Then bend it into push-pull input etc.... .

Thx-RNMarsh

output distortion cancellation ckt 1.png
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Old 8th August 2013, 07:20 PM   #250
dadod is offline dadod  Croatia
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Quote:
Originally Posted by RNMarsh View Post
What can you guys do with this? SIM it and add what is needed for output stage etc.

It uses cancellation technique to reduce distortion. [I'm into cancellation circuits now]

Then bend it into push-pull input etc.... .

Thx-RNMarsh

Attachment 364749
Thanks Richard, it looks interesting I will try to simulate(input) to see what is behind it.
BR Damir
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