Tag Archives: amp

Stereo Amplifier

My second attempt at mastering the LM386 Audio Amp IC (still sounds terrible).P1020890

 

Here’s the data sheet for the LM386 IC with some example circuits:
http://eicom.ru/pdf/datasheet/National_Semiconductor_PDFs/LM386/LM386.html

Instructables has a simple how-to:
http://www.instructables.com/id/LM386-Audio-Amplifier/

The schematic used in my project is a variation of this one from:
http://www.rason.org/Projects/icamps/icamps.htm
The only difference is that I added a 100nF from pin 7 to ground.  I think it helps keep the noise down.  There’s also two of everything except R1 and C1.

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Wow, my wires are all way too long.  It makes it very hard to get into a tiny box, but it works!

Stereo Preamp

My roommate found a nice Technics record player in a free box on the street.  It wasn’t working very well so he took it apart and cleaned it out and made some adjustments and got it working perfectly.  He plugged it in to his boom box, popped a record in and was really bummed because the audio was barely audible.  I ambled over and said, “Hey buddy, you need a preamp for a record player.”  He asked if I had one he could use.  I did not but I offered to try to build one, and I did.

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I found a schematic for a Low Noise Stereo Preamp module for sale that looked fairly reliable:
The module:
http://www.maplin.co.uk/low-noise-stereo-preamp-kit-220053

The schematic:
http://www.maplin.co.uk/media/pdfs/N47FL.pdf

Here is the relevant info from the pdf:

stereoprecomponentsstereoprediagram

I didn’t have the exact capacitors, or even the correct IC to build this… but I did anyway.  For the IC I used TL082CP in place of theNE5532 because that’s what The Shack had.  It seems to work just fine, and I can always swap it out later.

Here is the inside:

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It all just barely fits into the case without bulging:P1020874