Automatic idle current amplifier

senicz · 27th February 2006, 12:08 PM

idea

I_Forgot · 27th February 2006, 01:18 PM

So what's the idea?

I_F

Eva · 27th February 2006, 08:28 PM

The voltage drop across R4 and R5 caused by constant currents flowing from CS1 and CS2 is automatically reflected to R6 and R7 by the op-amps, thus bias current is always 100mA despite any change in operating conditions. Bias setting is kept even if you swap the output devices by other model with different Vbe.

I have developed something similar, but made in a more practical way with discrete components, as most op-amps won't be fast enough for such a task.

That thread shows my circuit and the working prototype:

Reinventing the N-channel wheel?

Leolabs · 1st March 2006, 01:17 AM

I have seen the actual circuit in a Chinese magazine,but not much talk about how it sound.

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27th February 2006, 01:18 PM	#2
I_Forgot diyAudio Member Join Date: Jan 2005 Location: Phoenix, Az.	So what's the idea? I_F

27th February 2006, 08:28 PM	#3
Eva diyAudio Member Join Date: Oct 2003 Location: Near the sea	The voltage drop across R4 and R5 caused by constant currents flowing from CS1 and CS2 is automatically reflected to R6 and R7 by the op-amps, thus bias current is always 100mA despite any change in operating conditions. Bias setting is kept even if you swap the output devices by other model with different Vbe. I have developed something similar, but made in a more practical way with discrete components, as most op-amps won't be fast enough for such a task. That thread shows my circuit and the working prototype: Reinventing the N-channel wheel?

1st March 2006, 01:17 AM	#4
Leolabs diyAudio Member Join Date: Dec 2004 Location: Bukit Mertajam	I have seen the actual circuit in a Chinese magazine,but not much talk about how it sound.

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