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Old 7th March 2008, 03:53 PM   #1
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Wink My version of GC, a LM3886 based

Hi All,

Just wanna share my version of Gainclone using LM3886..
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Old 7th March 2008, 04:57 PM   #2
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Oops...
Forgot the attachment!! Sorry...
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Old 7th March 2008, 05:00 PM   #3
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Another view..

Bought in a kit mode… Toroid is 300VA, using 18V supply from it with Carlos FM’s snubber circuit design on the PS PCB (thanks for sharing Carlos!!)
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Old 7th March 2008, 05:07 PM   #4
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PCB view...

Simple PCB layout, several Riken RM resistors , one 0.7uH inductor paralleled with 10R 1 Watt resistor (at bottom side of PCB), Nichicon Gold 47uF, Nippon Chemicon 100uF...

LM3886 supply pins (at the bottom side) decoupled to ground with 3300pF Wima FKS and ground pin connected to central grounding with 22K Resistor... reducing the DC offset from 30mV to approx. 4mV....
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Old 7th March 2008, 05:09 PM   #5
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Another pic
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Old 7th March 2008, 05:12 PM   #6
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Last pic..

Input Buffer BU-2 from Audio-GD…

Really improves the sound performance

Overall... really satisfied with this new toy...
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Old 7th March 2008, 07:09 PM   #7
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The pictures are difficult to follow. Did you have your own PCB's made ? if so show us the schematic. I have not used an inductor. where have you put it ?
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Old 8th March 2008, 10:39 AM   #8
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Hi Puffin,

Thanks for your respond..
Enclosed please find the schematic....

The PCB was purchased (together with the components, toroids, etc) in a kit form from a local electronic supplier in Jakarta, Indonesia (Mr. Alex MNP at www.langsungjadi.com).

I put the inductor as per schematic, parallel with R7...

Problem is... now I'm hearing very small hum...
(shouldn't be isn't it ?)


Regards,
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Old 8th March 2008, 10:45 AM   #9
Puffin is offline Puffin  United Kingdom
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The one thing that is different to the circuit I used is the use of the inductor. Do you know why it is there ? I understand that inductors pick up RFI.
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Old 8th March 2008, 11:47 AM   #10
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The output inductor is for isolating the amp against capactive load but also to block RFI picked up from the speaker cable.
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