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Old 18th March 2011, 10:13 PM   #3691
maxente is offline maxente  Romania
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this is the PCB i use
you must open the files with EAGLE

when i print this i forgot to disable the mirror option that's why some resistor apear to cross other resistors

after i did those modifications whit no exageration the board (2xNMOS200 on single board) works for the first time i power up

i use press n' peel metod to create pcb
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File Type: zip NMOS200.ZIP (74.9 KB, 251 views)
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Old 19th March 2011, 06:42 AM   #3692
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Originally Posted by maxente View Post
i use irfp240 for output stage and bd139 for termal track
for adjusting bias i use a normal digital ampermeter in series with +v rail
(i know it was better to set bias with 100ohm /5w and 10ohm resistor as quasi sugested in his web site http://sites.google.com/site/quasisdiyaudiosite/home)
first befor powering up i set vr2 cursor to R13 i use a jumper in input
then powering up
i set ampermeter to 250mA and then adjust vr2 to get 50mA
after that adjust offset to les 10mV (i don't known exact value because it was a few month ago)

the amp is still working even whit low v rail of +/-32v
i use it with 8 ohm speakers and sensitivity (1w/1m): 90 dB
and i think i got about of 50w because of low v rail

but it sounds very loud and clear to (i think it's because of the sensitivity of the speaker)

romanian forum is Forumul electronistilor • Prima pagin?
for thermal tracking is it bc546 pins and bd139 pins are same.
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Old 19th March 2011, 09:55 AM   #3693
AndrewT is online now AndrewT  Scotland
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bd139 is the same as all To126 pin out (ecb). This is exact reverse of To220 pin out (bce).
The bc5xx pin out is cbe.
Not the same.
As far as I know all bjt power devices have collector as the middle pin.
All Vfet power devices have drain as middle pin.
All latfet power devices have source as middle pin.
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Old 21st March 2011, 02:08 PM   #3694
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for nmos 200 what is the maximum input signal level?
can i use led to input signal? so the input signal voltage 2 or more the led will blink. is it correct method
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Old 25th March 2011, 01:26 AM   #3695
maxente is offline maxente  Romania
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Default nmos200 pcb

hey everybody

what do you think about this version of nmos200 pcb whit 2 pairs of irfp?

if somebody wants this version of scematic pcb just let me known
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File Type: jpg nmos200.jpg (90.4 KB, 606 views)
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Old 25th March 2011, 04:41 AM   #3696
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Originally Posted by maxente View Post
hey everybody

what do you think about this version of nmos200 pcb whit 2 pairs of irfp?

if somebody wants this version of scematic pcb just let me known
did u check this amp. how many watts and what is transformer voltage?

is your nmos200 transistor getting very hot?
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Old 25th March 2011, 11:07 PM   #3697
maxente is offline maxente  Romania
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this schematic you see here is the one i use and posted here Power amp under development whit one pair irfp
basically is the original nmos200 whit one more pair of irfp
i do not see why this may not work
i think the power whit 2 pairs of irfp is around 80w 8 ohm (i think)
somebody correct me if i'm wrong

the transformer voltage should not exceed +/-50V as quasi said
but if you want to increase rail voltage more then +/-50 you may need to change T1, T5 to 2sc1845 and R7 (10K) to 18K or to be sure check nmos350/500 schematic for modifications
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Old 26th March 2011, 10:01 AM   #3698
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Quote:
Originally Posted by maxente View Post
this schematic you see here is the one i use and posted here Power amp under development whit one pair irfp
basically is the original nmos200 whit one more pair of irfp
i do not see why this may not work
i think the power whit 2 pairs of irfp is around 80w 8 ohm (i think)
somebody correct me if i'm wrong

the transformer voltage should not exceed +/-50V as quasi said
but if you want to increase rail voltage more then +/-50 you may need to change T1, T5 to 2sc1845 and R7 (10K) to 18K or to be sure check nmos350/500 schematic for modifications

in quasi website one pair output gives 200w into 4ohm.
why your 2 pairs output deliver 80w into 8ohm.
why is low wattage of yous?
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Old 26th March 2011, 10:19 AM   #3699
AndrewT is online now AndrewT  Scotland
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why is low wattage of your amplifier?
+-50Vdc (from a 35+35Vac transformer) limits the maximum output voltage to ~38Vpk with a Source Follower output stage. This gives ~90W into 8r0.
80W (35.8Vpk) into 8ohm speaker seems very normal for a mosFET amplifier as a continuous maximum rating.
It might be able to give as much as 42Vpk as a transient peak capability, if the duty cycle is low enough.

Why do you think it should be any different?
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Last edited by AndrewT; 26th March 2011 at 10:22 AM.
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Old 26th March 2011, 12:13 PM   #3700
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Quote:
Originally Posted by maxente View Post
hey everybody

what do you think about this version of nmos200 pcb whit 2 pairs of irfp?

if somebody wants this version of scematic pcb just let me known
is it irfp260 or 240 best?
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