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Old 2nd April 2007, 11:55 AM   #1
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Default Boras Legend 4 Mosfet Amp

the original problem was when tryied to operate boras amp legend 4 with voltage 60-66vdc per rail ......

it all end up to almost 150 very expensive mosfets send to outer space while testing and trying to make it work ......

input was to sensitive to anything like a hot suap of plugs or just a litle bit of overdrive

bora of course recomended to add 0.18R 5W to the out of every mosfet as first change

and then a 33-56 pf miller styroflex capacitor between b and c on the MJE 340 vas amplifier to improove some ocilation was there

schematic is also available ......

still didnt work

destroyer x a very nice guy from brasil his original name is Carlos Eugênio Mergulhão - Destroyer x [B] and me worked out some mods and in real life this all seems to work no matter if used or abused ha ha ha ....

the new schematic is also available
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Old 2nd April 2007, 11:57 AM   #2
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Default UPDATED SCHEMATIC

HERE IS THE UPDATED SCHEMATIC THAT CARLOS .... DESTROYER X AND ME COME UP WITH ......

THANKS
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Old 2nd April 2007, 08:31 PM   #3
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Default feedback changes

well all these feedback that chanched should make some diference....is it working now ????

also input capacitor is now smaller .... is the low end effected ???
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Old 2nd April 2007, 11:25 PM   #4
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Default !

Watch!

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Old 3rd April 2007, 04:01 AM   #5
fab is offline fab  Canada
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This circuit looks like a copy of the Harman Kardon Citation 12 mosfet version by Nelson Pass as disclosed in Audio Amateur in 1981...
why is it a Boras Legend?
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Old 3rd April 2007, 07:51 AM   #6
sith is offline sith  Croatia
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Well, it is HC12, slightly moddified, and with new parts... Bora, Borivoje Jagodic, is the guy who did it... Why not Legend then
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Old 3rd April 2007, 09:59 AM   #7
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Default Bora is an electronic teacher....he is not too much young...he is an electronic

Enginneer teacher.....he is one of those that "create engineers"

It is possible that others had copied him too.

But also, it is not difficult that two folks create almost the same idea in different places...as all of us have brain inside skull.... even knowing that some folks has skull only to support hairs

There are things that makes some pressure on designers...now a days, i think, a digital amplifier may be something that will born everywhere in many different designs...and some of them will be almost the same without copies or spyes working on it.... sounds nice (not perfect) but it is small, low consumption and can be made inside small chips.

Also we are a result of our environment, this new world were communications are fast and easy..with internet informing almost all you need...those technologic evolutionary methods of amplifier design are beeing published around the world...and everybody has some influence on that...as not one appeared in this earth finishing some travel that started in Mars.... we go reading and learning other folks ideas, and this may result in something new...but not entirelly new, having influences of many designers.

regards,

Carlos
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Old 3rd April 2007, 11:05 AM   #8
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Default nice schematic

very nice schematic victor ....i presume is very powerfull also

but please can you tell us where is the relation with the legend 4 we are talking about .... (?????? )

also simulation looks prety nice also but this project ever made real life ?????? and how was it ????

can we see may be pictures of it ????
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Old 3rd April 2007, 11:22 AM   #9
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Default real life legend 8

there is a picture of real life as my friend Carlos Eugênio Mergulhão destroyer x use to say


it was designed to operate at 75+75 vdc and runing
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Old 3rd April 2007, 12:12 PM   #10
geminni is offline geminni  Yugoslavia
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Sakis, how did you atached the IRPF-s to the board?
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