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Old 30th September 2012, 08:07 AM   #1161
AndrewT is offline AndrewT  Scotland
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Would lsk170c be a good substitute?
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Old 1st October 2012, 06:43 PM   #1162
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Hello everyone and sorry for my bad English.
some time ago I bought the "JFET Boz" of JimsAudio that I would like to build. i have a transformer with double secondary (0-15V and 0-24v).
the 0-15v does go already the diamond buffer headamp of Sijosae.
now the question: the JFET Boz of JimsAudio can work with a voltage of 24V AC , if I am not mistaken, after the rectification bridge and filter capacitors will be 32-33v DC ?

Thanks in advance for any help.


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Old 10th October 2012, 07:43 PM   #1163
Abx74 is offline Abx74  France
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It depends of the bridge rectifier loss and your resistance value in your CRC PSU filter, but yes about 32V
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Old 12th October 2012, 06:55 AM   #1164
Tolu is offline Tolu  Germany
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Default Jims Audio PCB

I have got the PCB from Jims Audio, too. I just want to buy the necessary parts. In the part list of Jim is D6 not required. Therefore I just need a piece of wire, or?

On the photo at the website is just one Zener diode and not 4 as required in the part list or at the PCB! Has anyone assembled this PCB and can help?

Has anyone experience with this PCB and how is the quality of the power supply?

Last edited by Tolu; 12th October 2012 at 07:00 AM.
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Old 12th October 2012, 11:35 AM   #1165
ramallo is offline ramallo  Europe
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Quote:
Originally Posted by Tolu View Post
I have got the PCB from Jims Audio, too. I just want to buy the necessary parts. In the part list of Jim is D6 not required. Therefore I just need a piece of wire, or?
No, nothing on D6

In this photos I have replaced the diodes by a TL431 circuit (For fine tuning the V supply)

Click the image to open in full size.
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Old 12th October 2012, 11:38 AM   #1166
ramallo is offline ramallo  Europe
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Quote:
Originally Posted by robertor View Post
the JFET Boz of JimsAudio can work with a voltage of 24V AC , if I am not mistaken, after the rectification bridge and filter capacitors will be 32-33v DC ?
rob
Depends of the IDSS of the K170, with high V types you can use 30V of supply
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Old 12th October 2012, 12:03 PM   #1167
Tolu is offline Tolu  Germany
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Hio Ramallo,

normally, I will need the 4 Zener diodes!

I think it's a little bit like gambling if the 16V fit to the Idss of the 2SK170.

Would be nice to have a Idss -> V - table to see what's the best voltage for the specific jfet if you have no oscilloscope.
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Old 12th October 2012, 12:17 PM   #1168
ramallo is offline ramallo  Europe
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Quote:
Originally Posted by Tolu View Post
Hio Ramallo,

normally, I will need the 4 Zener diodes!

I think it's a little bit like gambling if the 16V fit to the Idss of the 2SK170.

Would be nice to have a Idss -> V - table to see what's the best voltage for the specific jfet if you have no oscilloscope.
Look Jfet BOZ
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Old 12th October 2012, 12:34 PM   #1169
tinitus is offline tinitus  Europe
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probably because its been copied from Nelson's first schematic showing 35V

whatever, here is my version
Attached Images
File Type: jpg IMG_7720.JPG (166.8 KB, 433 views)
File Type: jpg IMG_7714.JPG (188.4 KB, 194 views)
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Old 12th October 2012, 01:38 PM   #1170
Tolu is offline Tolu  Germany
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Quote:
Originally Posted by ramallo View Post
what a memory!

Nice idea with the little TL431 PCB! Does it work as you planned?

I'm considering to use 2 lead batteries for a phono pre so there would be enough power to drive the jfet boz and a DAC.

@tinitus: the chinese are copying anything. Not innovative but cheap.
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