what can i use...

benmanf · 25th May 2004, 11:15 AM

I want to build my first amp

...
i think i gonna build the p3a

...

what transistors can i use for the p3a instead of:
MJE15034
MJE15035
MJL4302
BC546
MJL4281

or maybe i cant?

jaycee · 25th May 2004, 12:20 PM

BD139/140 instead of MJE15034/MJE15035, TIP29/30 should also work.

MJ15003/4 instead of MJL4281/4302, although any suitable power stage transistor should also work.

Pretty much any small signal transistor with Ic>=100mA, Vceo >= 65V and Vcbo>=80V, low noise ones are best, 2N5551 will work.

If you are making your own PCB you can customise it to pretty much anything you can get hold of. If you're planning to buy Rod's PCB you may be a bit restricted though to transistors having same or similar pinouts.

benmanf · 25th May 2004, 12:29 PM

another question:

i have 12V and 24V transformers

can i connect them somehow and get 36V ?

sss · 25th May 2004, 03:26 PM

i think using only 24V transformer will be enough - after the rectifiers the voltage will be approx 33V

Christer · 25th May 2004, 03:30 PM

There are probably very many transistors you could use.
The question is rather what you can buy easily where you live
and that can be used instead, if the "real" ones are difficult to
get for you.

jaycee · 25th May 2004, 08:29 PM

24V transformer will work best, what is more important is the VA rating of the transformer, under 120VA is not really going to provide satisfactory performance for one channel. 250VA-300VA is recommended for a stereo pair of these amps.

destroyer X · 26th May 2004, 06:31 AM

I think its a good choise, will work very well.

Carlos

benmanf · 26th May 2004, 08:07 AM

THANK YOU ALL!!!

NOW I HAVE MORE CHANCES TO FIND THE PARTS I NEED

AND I DONT NEED TO BUY A NEW TRANSFORMER...
(MY 24v IS VERY POWERFUL)

25th May 2004, 11:15 AM	#1
benmanf diyAudio Member Join Date: May 2004 Location: Northern Israel	what can i use... I want to build my first amp... i think i gonna build the p3a... what transistors can i use for the p3a instead of: MJE15034 MJE15035 MJL4302 BC546 MJL4281 or maybe i cant?

25th May 2004, 12:29 PM	#3
benmanf diyAudio Member Join Date: May 2004 Location: Northern Israel	thank you!! and.... another question: i have 12V and 24V transformers can i connect them somehow and get 36V ?

26th May 2004, 06:31 AM	#7
destroyer X diyAudio Member Join Date: Feb 2004 Location: Recife - Brasil Northeast	Jaycee transistor choice is very good I think its a good choise, will work very well. Carlos __________________ Try to build an amplifier folks ... it is pure adrenaline!

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25th May 2004, 12:20 PM	#2
jaycee diyAudio Member Join Date: Apr 2004 Location: Norwich, UK	BD139/140 instead of MJE15034/MJE15035, TIP29/30 should also work. MJ15003/4 instead of MJL4281/4302, although any suitable power stage transistor should also work. Pretty much any small signal transistor with Ic>=100mA, Vceo >= 65V and Vcbo>=80V, low noise ones are best, 2N5551 will work. If you are making your own PCB you can customise it to pretty much anything you can get hold of. If you're planning to buy Rod's PCB you may be a bit restricted though to transistors having same or similar pinouts.

25th May 2004, 03:26 PM	#4
sss diyAudio Member Join Date: Jul 2003 Location: Israel , haifa	i think using only 24V transformer will be enough - after the rectifiers the voltage will be approx 33V

25th May 2004, 03:30 PM	#5
Christer diyAudio Member Join Date: Sep 2002 Location: Sweden	There are probably very many transistors you could use. The question is rather what you can buy easily where you live and that can be used instead, if the "real" ones are difficult to get for you.

25th May 2004, 08:29 PM	#6
jaycee diyAudio Member Join Date: Apr 2004 Location: Norwich, UK	24V transformer will work best, what is more important is the VA rating of the transformer, under 120VA is not really going to provide satisfactory performance for one channel. 250VA-300VA is recommended for a stereo pair of these amps.

26th May 2004, 08:07 AM	#8
benmanf diyAudio Member Join Date: May 2004 Location: Northern Israel	THANK YOU ALL!!! NOW I HAVE MORE CHANCES TO FIND THE PARTS I NEED AND I DONT NEED TO BUY A NEW TRANSFORMER... (MY 24v IS VERY POWERFUL)

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