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Old 6th December 2005, 02:40 AM   #21
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someone ask for a schematic? this project went through many iterations ---

here's the unregulated version:

Click the image to open in full size.
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Old 13th March 2008, 02:51 AM   #22
RS232 is offline RS232  United Kingdom
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Default Matching Mosfets

Hi to everybody.
This is my first post, so.....
I know this is an old topic/tread but I have been looking for a solution to my problem(?) and cant find one.
I'm trying to match some mosfets and everything is going (or not) wrong.
I am following the instructions in the Passdiy webpage and the ones in here, but I still don't get the VGS between 3/4.6V my lower value is 0.842 and the higher is 1.120V.
My question is ... what am I doing wrong ?
My power supply is 18V and I'm using a 150 Ohms resistor the mosfets are the 2sj50/2sk135 (I have lots of them with same batch code).
Hope someone can light me up.

Rick
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Old 13th March 2008, 03:25 AM   #23
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Without having tracked down datasheets for those parts I may be blowing smoke, but methinks you have lateral MOSFETs instead of vertical.

Grey
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Old 13th March 2008, 06:01 AM   #24
EUVL is offline EUVL  Europe
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Grey is correct. 2SK135, etc are lateral FETs :

http://www.diyaudio.com/forums/showthread/t-19789.html

Your measured Vgs is normal. Please check datasheet.


Patrick
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Old 13th March 2008, 06:06 AM   #25
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Default Re: Matching Mosfets

Quote:
Originally posted by RS232


... but I still don't get the VGS between 3/4.6V my lower value is 0.842 and the higher is 1.120V.
My question is ... what am I doing wrong ?
My power supply is 18V and I'm using a 150 Ohms resistor the mosfets are the 2sj50/2sk135 (I have lots of them with same batch code).
Hope someone can light me up.


You are doing nothing wrong.
2SJ50/2SK135 has lower Vgs compared with IRFP.
I liked 2SJ50/2SK135 when I built my A/B class power amp.
As far as I remember, Goldmund also used them for their power amps . . .


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Old 13th March 2008, 02:15 PM   #26
RS232 is offline RS232  United Kingdom
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Default Matching Mosfets

Thanks thats good to know
According to the datasheet for the 2sj50/2sk135 they have a Gate-Source cutoff voltage (VGSoff) 0.15 to 1.45V.
The ones I want to replace (IRF230/IRF9230) have a VGS from 2 to 4V.
Now I have another question
Can I use the 2sj50/2sk135 in one of the papas amps like the A75 or any other Aleph amps ?

Rick
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Old 13th March 2008, 04:16 PM   #27
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We seem to have a lot of overlapping threads these days. There was just another thread where someone was putting lateral parts into an Aleph. The quick and easy answer is yes, you can use laterals in place of verticals in most cases. However, you will have to attend to the different bias requirements.

Grey
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Old 13th March 2008, 04:36 PM   #28
AndrewT is offline AndrewT  Scotland
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Laterals have an admittance/transconductance of around 1S whereas Verticals are around 4S.

Thus Laterals require a much higher voltage swing to generate the same output current.
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Old 8th September 2008, 06:07 PM   #29
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This is a good sign -- the IRFP MOSFETs (Vishay Italia) seem to be more tightly grouped than the IRFP's from other parts of the world. This is the first group from Vishay Italia.
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Old 10th January 2011, 02:56 PM   #30
Gudmund is offline Gudmund  Iceland
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Default 2SJ50 2SK135 Hitachi matching circuit

Quote:
Originally Posted by RS232 View Post
Hi to everybody.
This is my first post, so.....
I know this is an old topic/tread but I have been looking for a solution to my problem(?) and cant find one.
I'm trying to match some mosfets and everything is going (or not) wrong.
I am following the instructions in the Passdiy webpage and the ones in here, but I still don't get the VGS between 3/4.6V my lower value is 0.842 and the higher is 1.120V.
My question is ... what am I doing wrong ?
My power supply is 18V and I'm using a 150 Ohms resistor the mosfets are the 2sj50/2sk135 (I have lots of them with same batch code).
Hope someone can light me up.

Rick
Hi , as being new in electronics I need a simple circuit to match a double pair of 2SJ50 / 2SK135 Hitachi mosfets for a 100watt amplifier.

Would it be difficult for "RS232" or someone else to draw the curcuit to show me the setup for matching output Hitachi mosfets?

Thanks for your cooperation in advance.

Gudmund
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