Mirror image IS & VAS BJT amp examples?

sam9 · 6th June 2004, 06:07 PM

Anyone have postable schematics for a BJT output amp with mirror image input and voltage amplification stages?

I'm looking for examples OTHER THAN Slone in order to get some idea of the range of approaches.

Also I'm interested in discrete rather than opamp input sections.

Part off the reason was I was killing time web browsing for these and nothing came up other than Slone, Opamp bases inputs and FET output variations. So I'm left with some conjectures A-the topology is rarer than one might think, B- it's not rare but is deep proprietary secret, C- I just can't come up with the right search string. I vote for "C" as the most likely but "A" and "B" would be more interesting explanations.

kevin gilmore · 6th June 2004, 07:33 PM

like this?
http://gilmore.chem.northwestern.edu/dynahi2.gif

cunningham · 30th June 2004, 12:05 AM

Quote:

Originally posted by kevin gilmore
like this?
http://gilmore.chem.northwestern.edu/dynahi2.gif

how do you keep from over biasing the output stage?

Thermal runaway?

cunningham · 30th June 2004, 12:10 AM

Tis my understanding that you could use a single diff. amp. circuit and VAS in class A. Then get your current from emitter follower circuit, class AB.

less noise and better stability and less

thanh · 30th June 2004, 07:44 AM

Quote:

better stability

Probadly! My orcads also says like that.My amp often failures

richie00boy · 30th June 2004, 08:20 AM

Check out the "Leach Low TIM Amp"

sajti · 30th June 2004, 08:46 AM

Quote:

Originally posted by cunningham

how do you keep from over biasing the output stage?

Thermal runaway?

Thermal runaway is not real problem with 10ohms emitter resistors.

sajti

6th June 2004, 06:07 PM	#1
sam9 diyAudio Member Join Date: Jun 2002 Location: Left Coast	Mirror image IS & VAS BJT amp examples? Anyone have postable schematics for a BJT output amp with mirror image input and voltage amplification stages? I'm looking for examples OTHER THAN Slone in order to get some idea of the range of approaches. Also I'm interested in discrete rather than opamp input sections. Part off the reason was I was killing time web browsing for these and nothing came up other than Slone, Opamp bases inputs and FET output variations. So I'm left with some conjectures A-the topology is rarer than one might think, B- it's not rare but is deep proprietary secret, C- I just can't come up with the right search string. I vote for "C" as the most likely but "A" and "B" would be more interesting explanations.

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6th June 2004, 07:33 PM	#2
kevin gilmore diyAudio Member Join Date: May 2002 Location: wheeling illinois	like this? http://gilmore.chem.northwestern.edu/dynahi2.gif

30th June 2004, 12:10 AM	#4
cunningham diyAudio Member Join Date: Jun 2004 Location: Knoxville	Tis my understanding that you could use a single diff. amp. circuit and VAS in class A. Then get your current from emitter follower circuit, class AB. less noise and better stability and less

30th June 2004, 08:20 AM	#6
richie00boy Did it Himself diyAudio Member Join Date: Nov 2003 Location: Gloucestershire, England, UK	Check out the "Leach Low TIM Amp"

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