amp using tda7250 driver ic?

partyjups · 19th October 2001, 04:51 PM

I have seen this page with a circuit layout for 2x130w into 4 ohms
http://home.eunet.cz/rysanek/cheapamps_en.html
I was then thinking about if it is posible to use the circuit with higher voltage (the the Tda7250 can be used with up to 90 v) and use maybe MJ15024/23 or BUZ900D/905D

http://www.semelab.co.uk/magnatec_mosdata.htm

to get a low cost amp of about 2x200w into 8 ohms on a single pcb.
I know that it's not a high end sulution. I just need low cost high power.

any advice is welcome. JC DK.

Opie · 21st October 2001, 05:12 AM

partyjups have you used the pcb for this amp? How is the quality of the sound?

Brian

djk · 21st October 2001, 06:58 AM

OK, here is a very simple idea: http://www.delphion.com/cgi-bin/view...d/US05029299__ Items 34,36 are the main filter caps.Note that what is normally grounded, ie: the center tap of the transformer, is actually the 'hot' output of the amplifier and that the outputs of the amp drive what is normally 'ground'.For 200W RMS at 8 ohms you will need a pair of 3,300µf(or larger)80V(or higher)caps and a 100VCT(50-0-50)400VA transformer and only one pair of BUZ900D/905D.These are item 44,46 short out 48,50 and 28,30 are not used.Items 58,62,64,76 are 1N4004 type diodes.Items 70,72,80,84 are 1N4744 15V 1W zener.The ratio of 39/42 sets the gain of the amplifier.Items 68,74,78,82 are 22µF+.1µF 25V and add a 22µF 100V to 34,36 while you are at it.Items 56,60 are 3.3K with 52,54 changed to 330 ohms and a 2K bias pot added across what is shown as the bases of 44,46(the BUZ parts).The BUZ will need 220 ohm gate resistors.Note that the cases of the BUZ outputs are at ground potential and need no performance robbing insulators.This is not a new idea.The TransNova series of amps from Acoustat/Hafler/Rockford are all built this way.Items 22,26 are 3.3K 2W (a bit hot, or 5W if you want them cold).Item 66 is 1K 5W.Add flyback diodes to 44,46(and 10V gate zeners if you want them)and don't forget the output zobel of .1µF+10 ohms.A NE5534 works great as the driver IC.

Opie · 21st October 2001, 02:55 PM

djk,
If I wanted 150 rms into 4 ohm from the Tda7250 circuit, what mods would I need to make?

Brian

21st October 2001, 05:12 AM	#2
Opie diyAudio Member Join Date: Oct 2001 Location: UW Stevens Point Campus	pcb? partyjups have you used the pcb for this amp? How is the quality of the sound? Brian

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19th October 2001, 04:51 PM	#1
partyjups diyAudio Member Join Date: May 2001 Location: Denmark	I have seen this page with a circuit layout for 2x130w into 4 ohms http://home.eunet.cz/rysanek/cheapamps_en.html I was then thinking about if it is posible to use the circuit with higher voltage (the the Tda7250 can be used with up to 90 v) and use maybe MJ15024/23 or BUZ900D/905D http://www.semelab.co.uk/magnatec_mosdata.htm to get a low cost amp of about 2x200w into 8 ohms on a single pcb. I know that it's not a high end sulution. I just need low cost high power. any advice is welcome. JC DK.

21st October 2001, 06:58 AM	#3
djk diyAudio Member Join Date: Feb 2001 Location: USA	OK, here is a very simple idea: http://www.delphion.com/cgi-bin/view...d/US05029299__ Items 34,36 are the main filter caps.Note that what is normally grounded, ie: the center tap of the transformer, is actually the 'hot' output of the amplifier and that the outputs of the amp drive what is normally 'ground'.For 200W RMS at 8 ohms you will need a pair of 3,300µf(or larger)80V(or higher)caps and a 100VCT(50-0-50)400VA transformer and only one pair of BUZ900D/905D.These are item 44,46 short out 48,50 and 28,30 are not used.Items 58,62,64,76 are 1N4004 type diodes.Items 70,72,80,84 are 1N4744 15V 1W zener.The ratio of 39/42 sets the gain of the amplifier.Items 68,74,78,82 are 22µF+.1µF 25V and add a 22µF 100V to 34,36 while you are at it.Items 56,60 are 3.3K with 52,54 changed to 330 ohms and a 2K bias pot added across what is shown as the bases of 44,46(the BUZ parts).The BUZ will need 220 ohm gate resistors.Note that the cases of the BUZ outputs are at ground potential and need no performance robbing insulators.This is not a new idea.The TransNova series of amps from Acoustat/Hafler/Rockford are all built this way.Items 22,26 are 3.3K 2W (a bit hot, or 5W if you want them cold).Item 66 is 1K 5W.Add flyback diodes to 44,46(and 10V gate zeners if you want them)and don't forget the output zobel of .1µF+10 ohms.A NE5534 works great as the driver IC.

21st October 2001, 02:55 PM	#4
Opie diyAudio Member Join Date: Oct 2001 Location: UW Stevens Point Campus	djk, If I wanted 150 rms into 4 ohm from the Tda7250 circuit, what mods would I need to make? Brian

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