2n3055

nbcd · 24th August 2004, 11:17 AM

hy al
can anyone give me an amplifier schematic that uses 2n3055?
I prefer i would be rated 80W or heigher
thanks
Best regards!

paulb · 24th August 2004, 02:24 PM

Here's one: http://sound.westhost.com/project12.htm

There are also lots using the 2N3055 / MJ2955 pair.

Real_Macgyver · 24th August 2004, 05:37 PM

I can't understand why he is using a capacitor in series with Q1:s emitter.

Why don't use a current mirror instead?

jaycee · 24th August 2004, 06:12 PM

The AmpsLab C70 seems to fit the bill. Not quite 80W, but near as. You could probably add another pair on the outputs and raise the rail voltage to make it 80W if you really wanted.

http://www.ampslab.com/c70.htm

Getting anything higher with those transistors is a bit of a no-no unless you're prepared to parallel a load of them. Doing that would probably be more costly than just buying MJ150003/4 or MJ21193/4, unless of course you happen to already have a large stock of N3055 / MJ2955

djk · 25th August 2004, 07:58 AM

" Post #3
I can't understand why he is using a capacitor in series with Q1:s emitter.

Why don't use a current mirror instead?"

Its the feedback loop, why would I want a current mirror there?

Ouroboros · 25th August 2004, 08:10 AM

Quote:

Originally posted by Real_Macgyver
I can't understand why he is using a capacitor in series with Q1:s emitter.

The capacitor sets the dc gain to unity.

nbcd · 25th August 2004, 08:21 AM

thanks all for your help

azira · 25th August 2004, 04:49 PM

Quote:

Originally posted by djk
" Post #3
I can't understand why he is using a capacitor in series with Q1:s emitter.

Why don't use a current mirror instead?"

Its the feedback loop, why would I want a current mirror there?

Yes, but that isn't the complete answer. How is the DC bias controlled/evaluated if there is a cap in the emitter path?
--
Danny

Eva · 25th August 2004, 05:22 PM

That transistor is biased through the 10K resistor from emitter to output. The capacitor estabilishes only the AC path. The feedback signal is applied directly to the emitter while the input signal is applied to the base

It's surprising how people gets lost when they look at amplifier schematics without long tailed pairs or current sources

Actually this old-school layout has probably higher gain and higher bandwith than any LTP with current sources

nbcd · 26th August 2004, 07:53 AM

Can i use BU406 instead of 2n2955?

24th August 2004, 11:17 AM	#1
nbcd diyAudio Member Join Date: Apr 2003 Location: suceava	2n3055 hy al can anyone give me an amplifier schematic that uses 2n3055? I prefer i would be rated 80W or heigher thanks Best regards! __________________ eugen

25th August 2004, 08:21 AM	#7
nbcd diyAudio Member Join Date: Apr 2003 Location: suceava	thanks all for your help __________________ eugen

26th August 2004, 07:53 AM	#10
nbcd diyAudio Member Join Date: Apr 2003 Location: suceava	Can i use BU406 instead of 2n2955? __________________ eugen

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24th August 2004, 02:24 PM	#2
paulb diyAudio Member Join Date: Jun 2001 Location: Calgary	Here's one: http://sound.westhost.com/project12.htm There are also lots using the 2N3055 / MJ2955 pair.

24th August 2004, 05:37 PM	#3
Real_Macgyver diyAudio Member Join Date: Aug 2004 Location: Sweden	I can't understand why he is using a capacitor in series with Q1:s emitter. Why don't use a current mirror instead?

24th August 2004, 06:12 PM	#4
jaycee diyAudio Member Join Date: Apr 2004 Location: Norwich, UK	The AmpsLab C70 seems to fit the bill. Not quite 80W, but near as. You could probably add another pair on the outputs and raise the rail voltage to make it 80W if you really wanted. http://www.ampslab.com/c70.htm Getting anything higher with those transistors is a bit of a no-no unless you're prepared to parallel a load of them. Doing that would probably be more costly than just buying MJ150003/4 or MJ21193/4, unless of course you happen to already have a large stock of N3055 / MJ2955

25th August 2004, 07:58 AM	#5
djk diyAudio Member Join Date: Feb 2001 Location: USA	" Post #3 I can't understand why he is using a capacitor in series with Q1:s emitter. Why don't use a current mirror instead?" Its the feedback loop, why would I want a current mirror there?

25th August 2004, 05:22 PM	#9
Eva diyAudio Member Join Date: Oct 2003 Location: Near the sea	That transistor is biased through the 10K resistor from emitter to output. The capacitor estabilishes only the AC path. The feedback signal is applied directly to the emitter while the input signal is applied to the base It's surprising how people gets lost when they look at amplifier schematics without long tailed pairs or current sources Actually this old-school layout has probably higher gain and higher bandwith than any LTP with current sources

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