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Chip Amps Amplifiers based on integrated circuits

Design from scratch (LM3886)
Design from scratch (LM3886)
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Old 25th August 2004, 12:43 PM   #11
carlmart is offline carlmart  Brazil
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Originally posted by VEC7OR

Do I miss something really important ? Ugh, do I need a resistor between the ground and the non-inverting input or I just connect non-inverting to the ground ?
Use some resistance or you will have offset.

You can try from 220K to 10K and see which works better for sound. Also listen to it with and without parallel cap on resistor.


Carlos
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Old 25th August 2004, 01:18 PM   #12
Ouroboros is offline Ouroboros  England
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Your dc impedance from the - input to ground is 220k, (The input is capacitor-coupled so has an infinite dc impedance. To get the best thermal tracking of the dc offset you could put a 220k resistor from the + input to ground to match the dc impedance on both inputs.

My view is that 220k will increase the noise. Try it with a direct short from + to ground as you have at the moment. If the dc offset voltage is OK then you could leave it as it is.

(The other option is to put a 220k resistor, but bypassed with a capacitor.)
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Old 27th August 2004, 10:37 AM   #13
VEC7OR is offline VEC7OR  Lithuania
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Hm I think thats about it. Any suggestions ?
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Old 27th August 2004, 10:50 AM   #14
jan.didden is offline jan.didden  Europe
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The 220k at the pos input will generate a lot of noise. You should decouple it.

Jan Didden
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Old 27th August 2004, 11:14 AM   #15
VEC7OR is offline VEC7OR  Lithuania
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Design from scratch (LM3886)
10nF ceramic will do ?
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Old 27th August 2004, 11:36 AM   #16
VEC7OR is offline VEC7OR  Lithuania
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Design from scratch (LM3886)
PSU schematic.
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Profanity took a very interesting form in Russia where there exists a language of sorts, most of its words based on four basic profane roots - nouns p...is, wh.0.e, c..t and verb f..k. It is possible to sensibly communicate using just these four basic roots.
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Old 22nd September 2004, 07:41 PM   #17
VEC7OR is offline VEC7OR  Lithuania
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The PCB, I'll use the laser printer and steam iron to transfer it to PCB, then peel the paper after its soaked in water and then I'll etch it
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Profanity took a very interesting form in Russia where there exists a language of sorts, most of its words based on four basic profane roots - nouns p...is, wh.0.e, c..t and verb f..k. It is possible to sensibly communicate using just these four basic roots.
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Old 22nd September 2004, 07:45 PM   #18
VEC7OR is offline VEC7OR  Lithuania
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doh teh file
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Profanity took a very interesting form in Russia where there exists a language of sorts, most of its words based on four basic profane roots - nouns p...is, wh.0.e, c..t and verb f..k. It is possible to sensibly communicate using just these four basic roots.
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Old 22nd September 2004, 08:23 PM   #19
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I find it easier to use a permanent marker to draw the foil patterns. well, that's my choice.
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Old 22nd September 2004, 10:00 PM   #20
VEC7OR is offline VEC7OR  Lithuania
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epp, tried that too, tried drilling them, now wanna try this, maybe even I'll try resist coated boards, but thats later on some bigger boards.

Hm, I wonder how good I'll be ? will the toner hold good ?
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