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Old 29th April 2012, 03:09 PM   #411
sonnya is offline sonnya  Denmark
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Good progress Joachim.

When i am done the gerber files, the BOM and the Pick and place data.

The board is made with SMT for the frontend.

I can produce the board with all SMT on them, but with above files i will upload everyone else can also.

Regarding the mosfet drivers. Is there an reliable source for 2SK216 and 2SJ79?? Or should wi install IRF instead???
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Old 29th April 2012, 03:36 PM   #412
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Hi Sonnya

SMT parts are perfect choice here, since there are a lot small signal BJTs connected between themselves only. Try to make as compact PCB as possible.

There are few suppliers that can provide 2SJ79/2SK216. These are lateral mosfets (transconductance falls with higher temperature) so no problem with thermal runaway, also have integrated gate protection zeners - perfect drivers. Try to find these not IRFs.

I cannot wait to see your PCB
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Old 29th April 2012, 03:37 PM   #413
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I can get them still although i think Renaisas stopped production of this transistors. Exicon makes laterals but not TO220. One solution is to use big ones for the drivers too.
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Old 29th April 2012, 03:39 PM   #414
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Count me in for 2SJ79/2SK216, if you still can get them.
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Old 29th April 2012, 03:42 PM   #415
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Sure, i use 2SJ77 and 2SK214. They can stand enough voltage. I really whould not like to go to hexfets. I think laterals sound better, especially when you go down the drain.
They are excellent constant current souces.
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Old 29th April 2012, 03:44 PM   #416
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away goes trouble down the drain
LAST NIGHT A D.J. SAVED MY LIFE Lyrics INDEEP
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Old 29th April 2012, 04:02 PM   #417
sonnya is offline sonnya  Denmark
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Quote:
Originally Posted by Joachim Gerhard View Post
Sure, i use 2SJ77 and 2SK214. They can stand enough voltage. I really whould not like to go to hexfets. I think laterals sound better, especially when you go down the drain.
They are excellent constant current souces.
Last time the bag size was 500pcs and there also is a minimum buy.
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Old 29th April 2012, 05:19 PM   #418
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For this few amps we will build i have enough, but maybe.....
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Old 29th April 2012, 05:30 PM   #419
sonnya is offline sonnya  Denmark
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Second solution:

Raise frontend current 5x
Gateresistor reduced 5x
Maybe change the feedback network by reducing it 2x.

5mA in the front stage but still only 1mA in the input pair.

This Way the drive impedance for the mosfet is 5x lower. I Think this Will improve the thd performance simelar without the mosfet drivers.

Last edited by sonnya; 29th April 2012 at 05:50 PM.
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Old 29th April 2012, 06:42 PM   #420
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Sure, that will work too. Nevertheless i build the version with driver first and then we can compare.
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