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Old 15th April 2015, 03:28 PM   #1
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Default class A Buffer

I have attached the schematic and board layout for the buffer. I plan to copy and make 2 channels on the same pcb and use a single heatsink (along the length of the pcb) for all the 4 transistors. Any issues with this.
Do I need both R4 and R5 for ring of two ccs stability.
How does the layout look.
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Old 19th April 2015, 08:56 AM   #2
Calvin is offline Calvin  Germany
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Hi,

You may omit with R4. R5 has negligible impact and may be raised to 1k.
C3 should be a bipolar cap.
optional:
- You may split R1 in two resistors with increased value (5K-10k) and add a cap of a few F from the resistor mid-joint to the negative supply.
- You can omit with the output coupling caps using a active DC-servo that controls the idle current of the ccs, and a bias voltage and a source resistor for the MOSFET.
For an example of the servo circuit see my website calvins-audio-page.jimdo.com/ideas-and-circuits/buffers/hybrid-buffer-en/.
Scroll down to "Calvin-Buffer plus dc-servo".

jauu
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Old 19th April 2015, 09:32 AM   #3
AndrewT is offline AndrewT  Scotland
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Calvin,
the first 3 sch open out to full size by clicking on them.
But I can't expand the fourth one showing the DC servo.
Is it linked somewhere else?
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Old 19th April 2015, 10:09 AM   #4
Calvin is offline Calvin  Germany
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Hi,

Thanks for the note Andrew.
I changed it.

jauu
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Old 19th April 2015, 10:50 AM   #5
AndrewT is offline AndrewT  Scotland
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That works, thanks.
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