#1

Is this diagram right?
Because all the other amp diagrams have variable resistors inbetween the 1 and 8 pins instead of a 10uF capacitor.
And most of them have the negative of the speaker going to earth.

Also, if this diagram is correct, would replacing those 10uF capacitor to variable capacitors make a gain control?
And adding a variable resistor (pot) after the 0.22 capacitor would make a volume control, right?

Other amp diagram, ruby

Really sorry if this is the wrong place, or if questions like this shouldn't be asked.
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#2
Top and bottom schematics are totally different. If you read on the LM386 datasheet, it says "
Quote by LM386 Datasheet
To make the LM386 a more versatile amplifier, two pins (1
and 8) are provided for gain control. With pins 1 and 8 open the 1.35 kW resistor sets the gain at 20 (26 dB). If a capacitor is put from pin 1 to 8, bypassing the 1.35 kW resistor, the gain will go up to 200 (46 dB). If a resistor is placed in series
with the capacitor, the gain can be set to any value from 20 to 200.

*interesting note - there's an error there. It should be a 1.38kOHM resistor, not watt*.

So yes, both ways of setting the gain are right. If you notice in the first diagram, the negative rail of the speaker is going to the inverted output of the other LM386, so it's effectively a push-pull design.
"Everybody, one day will die and be forgotten. Act and behave in a way that will make life interesting and fun. Find a passion, form relationships, don't be afraid to get out there and fuck what everyone else thinks."
#3
One last question, Could I replace those 10uF capacitors with 1K-B Pots, like the ruby design?
I can't find any variable capacitors.
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#4
Quote by demonofthenight
One last question, Could I replace those 10uF capacitors with 1K-B Pots, like the ruby design?
I can't find any variable capacitors.


Yes. I did that with my Ruby and it works fine.
"Everybody, one day will die and be forgotten. Act and behave in a way that will make life interesting and fun. Find a passion, form relationships, don't be afraid to get out there and fuck what everyone else thinks."
#5
Thanks Random_hero, damn genious.
My very last question for tonight, if you dont mind answering, would this work? I've added a volume control and two 5k pots, as the 'little gem' original uses them and it sounds sweet (but not very loud).
Attachments:
Modified little gem mk2.JPG
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#6
What I would do personally is use a dual-gang 1K linear pot and see how that would go. If you didn't, you couldn't control the distortion by each IC at the same time, which might sound kind of funky. Interesting though...
"Everybody, one day will die and be forgotten. Act and behave in a way that will make life interesting and fun. Find a passion, form relationships, don't be afraid to get out there and fuck what everyone else thinks."
#7
thanks again
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