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Old 30th August 2006, 01:11 AM   #1
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Default simple high power sub amp

hi everybody...
i have on my lab 4 pairs of IRF640/9640, 8 IRFP250 and some op amps(uA741 and TL072)...
I want to build an amplifier capable of around 300W on 4ohms for drive my subwoofer...
can anyone suggest me a schematic of a very simple but powerfull(if possible) amp with this components??? it can be also a class B circuit...simple input op amp and power mosfets(quasi or full complementary). for power supply i have ready a huge toroidal transformer(350VA) with secondary of 40+40v...
waiting for replies...
tanks.......
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Old 30th August 2006, 01:19 AM   #2
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Ciao Flavio
Un circuito che ti consiglio è questo (progettato da QUASI).In teoria dovrebbe funzionare,aggiungi solo in serie a C12 un resistore da 4.7 Ohm 2W e aumenta il valore delle resistenze R20,21,22 e 23 a 150-180 Ohm
Tieni presente che con 40+40 v sul secondario non potrai ottenere i 300W/4 Ohm (tensione continua a vuoto di circa 54 + 54 v).
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File Type: pdf power amplifier atrk n-mos 1v1.pdf (35.7 KB, 188 views)
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Old 30th August 2006, 08:58 AM   #3
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ciao!!!
finalmente una sana schiacchierata in italiano.....


ho già provato a costruire questo ampli per ben 3 volte, ho usato 3 schemi diversi e altrettanti pcb... comincia a diventare una sfida personale e a costarmi parecchio in euri... il problema che mi si presenta è sempre lo stesso, sull' AP vedo solo le semionde positive, quelle negative, tranne che nel'istante in cui accendo il tutto non si fanno vedere minimamente....
proverò a rispolverare il tutto e a cambiare i valori delle resistenze di gate come mi consigli...

cercando tra i vecchi progetti da me realizzati ho trovato questo semplice ma ottimi ampli a mosfet che probabilmente conoscerai, si tratta del modulo FT15K della futura elettronica... osservando lo schema penso che potrei tranquillamente alzare la tensione di alimentazione e ottenere più potenza, magari sostituendo la prezionsa coppia di mos di potenza(visto il costo spropositato de quei gioiellini) con 3 coppie di irf640/9640...
che ne pensi?
grazie
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File Type: pdf 7100-ft15k.pdf (50.8 KB, 119 views)
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Old 30th August 2006, 09:16 AM   #4
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Ciao Flavio
speriamo che gli altri non si arrabbino.
E' molto strano che quel circuito non funziona.Io stesso ho realizzato un modello molto simile a questo per il mio amplificatore 7 canali per l'ambienza.
Prova momentaneamente a staccare i mosfet finali e la controreazione (R13 e R12),collega la base di T3 a massa e accendi il tutto.Misura qual'è la tensione su R16 e R19.Dovrebbe essere possibile regolarla con VR2 tra 3 e 4 volts circa UGUALE SULLE DUE RESISTENZE.Fammi sapere.
Ho visto lo schema che hai allegato e mi vengono alcuni dubbi.
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Old 30th August 2006, 09:18 AM   #5
MikeB is offline MikeB  Germany
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Hmm, others might also be able to participate if you continue in english... (in fact a forum rule)

Mike
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Old 30th August 2006, 09:24 AM   #6
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Sorry Mike B
you're right.
I will continue in english.
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Old 30th August 2006, 09:26 AM   #7
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yes, sorry mike now we continue in english...
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Old 30th August 2006, 09:34 AM   #8
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parsec, can i have your e-mail?
however, i think that there is problems with this configuration of circuit, specially on the right side of input pair(seems to not drive the negative mos driver) i think thath on right side the output must be exactly the inverted of the left side...i think......
so there can be problems with feedback no?
whath do you think about driving this amp with an op amp?
one non inverting for positive rail and one inverting for negative rail?, is for mr also an amp to learn to project amps
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Old 30th August 2006, 09:38 AM   #9
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Default for all members,read in english

The issue is the use of some components for a power amp.
I have suggested the power amp designed by Quasi.

Flavio88 has answered to me that this circuit will not work.

I have suggested to Flavio88 some procedures to test your amp:leave the output mosfets and leave R13 and R12 and connect the base of T3 via a 33K resistor.After power on ,measure the voltage across R16 and R19 it must regulated with VR2 at 3-4 volts SAME ON TWO RESISTORS.

For the circuit attached by Flavio I have some doubt.
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Old 30th August 2006, 09:44 AM   #10
EC8010 is offline EC8010  United Kingdom
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Gentlemen, the rules are that this forum is English-speaking...

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