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Old 13th January 2004, 11:54 AM   #1
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Question 100w Mosfet amp

Is this Mosfet amp(see the attached file) a simple good amp?
What do you think about it?

100W 8 Ohm +/-50V


components:

R1: 2,2 Kohm
R2: 47 Kohm
R3: 47 Kohm
R4: 3,9 Kohm
R5: 3,9 Kohm
R6: 1 Kohm
R7: 33 Kohm
R8: 12 Kohm 1 Watt
R9: 100 ohm
R10: 100 ohm
R11: 47 ohm
R12: 100 ohm
R13: 220 ohm trimmer m.o. p.5
R14: 100 ohm
R15: 100 ohm
R16: 100 ohm
R17: 4,7 ohm 2 Watt
(I resistori sono da 1/4 watt 5%
salvo diversa indicazione)
C1: 10 F 50 V elettrolitico rad.
C2: 47 pF ceramico
C3: 47 F 50 V elettrolitico rad.
C4: 6,8 nF ceramico
C5: 33 pF ceramico
C6: 33 pF ceramico
C7: 100 nF 100 V poliestere
C8: 220 F 50 V elettrolitico rad.
C9: 100 nF multistrato
C10: 220 F 50 V elettrolitico rad.
C11: 100 nF multistrato
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File Type: jpg ampli2.jpg (43.5 KB, 1087 views)
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Old 13th January 2004, 12:25 PM   #2
ratu is offline ratu  Spain
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c8,c10 only 220uF!!

At least 4700uF better 22000uf for both chanels

Ratu
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Old 13th January 2004, 01:25 PM   #3
Did it Himself
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That is the 'industry standard' MOSFET amp as designed by Hitachi when MOSFETs first became readily available. It has been cloned a thousand times, both commercially and DIY. It performs well, but there are improvements/better alternatives available nowadays.
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Old 13th January 2004, 03:53 PM   #4
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Default no, ratu!

220uF is the correct value as these caps are only for local/close decoupling. PSU smoothing caps are to be used in addition and these should be like you said.
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Old 13th January 2004, 09:21 PM   #5
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Thanks for all the answer

Regards
D.N.
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Old 14th January 2004, 05:39 AM   #6
palesha is offline palesha  India
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richie00boy said
"That is the 'industry standard' MOSFET amp as designed by Hitachi when MOSFETs first became readily available. It has been cloned a thousand times, both commercially and DIY. It performs well, but there are improvements/better alternatives available nowadays."

We r intersted in this type of schematics and more info.
MP
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Old 14th January 2004, 05:55 AM   #7
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Quote:
Originally posted by palesha
We r intersted in this type of schematics and more info.
MP
If you google for "FET amplifier circuit" or similar terms you get plenty of those and similar schematics. Also here in the forum you can find several examples.
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Old 14th January 2004, 06:32 AM   #8
ratu is offline ratu  Spain
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Default richieboy

Ok! if its only for decoupling, remember to put it as close as posible to te power mosfets.

Ratu
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Old 14th January 2004, 10:02 AM   #9
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Quote:
Originally posted by Cybergent


If you google for "FET amplifier circuit" or similar terms you get plenty of those and similar schematics. Also here in the forum you can find several examples.

Like this one

suggestions for improvement

Tony.
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Old 14th January 2004, 10:21 AM   #10
ratu is offline ratu  Spain
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Default T1,T2

It is very iportant that you buy many mirror transistors(10 or 20 units of T1 and T2) and measure the hfe of each one, try both which have the same hfe and in the case that you have many, try the maximum value of hfe.

This is aplicable for all mirror transistors!

RATU
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