Pocket Protest Audio Amp - LM386

zeturi

zeturi

DEMON PIE!
ALL CREDIT FOR THIS SCHEMATIC AND AMP GO TO OSGELD OVER AT INSTRUCTABLES, who said I could share his amp over here. It's a simple audio amp, can operate between 4-12 volts. Only takes four parts, all obtainable at radio shack for under $10, or be scavenged easily from other electronics:

10k potentiometer
220 uf 16v capacitor
0.1 uf ceramic cap
LM386 IC
Some wire

(LINKS TO CHEAP PARTS)
2x 10k Potentiometers http://cgi.ebay.com/2pcs-10K-B-Type-Lin ... 4aa213b90d

20x 0.1 uf Cermaic Capacitors http://cgi.ebay.com/20-pcs-0-1uF-50Vdc- ... 27b328b273

20x 220 uf 16v Electrolytic Capacitors http://cgi.ebay.com/20-pcs-220uF-16V-El ... 27b329719a

5x LM386 ICs http://cgi.ebay.com/5-pcs-LM386-LM386L- ... 5ad47a6a3b

http://i636.photobucket.com/albums/uu90/zeturi/easylm386.jpg
3szN4.jpg


That is how everything connects. If you take a look at osgeld's instructable, you'll see that he has a very compact arrangement for the parts.

If you want to know, gain is 20 with this schematic. If you want, connect a 10uf capacitor between pins 1 and 8, with the negative leg towards pin eight. This will give the amp a 200 gain. I tried this, but I found that it made sounds way too staticy and distorted. Without it, it still sounds good.

Enjoy your small, cheap audio amp. ;)
 
Re: Dummy's Audio Amp - LM386

Cool, thanks for posting this! I may use this audio amp for a NOACp or an SDGOACp.
 
Re: Dummy's Audio Amp - LM386

Ok, replaced the instructable link in the sticky with this thread.
 
I'm glad this is of use. I'm pretty sure you could replace the pot with tacts if you prefer, but I would have no idea how. I heard about that somewhere, I'll do some quick hunting and see what comes up.
 
I would like to bump this topic with some link to cheap ebay suppliers. The stuff that I'm linking is:

2x 10k Potentiometers http://cgi.ebay.com/2pcs-10K-B-Type-Lin ... 4aa213b90d

20x 0.1 uf Cermaic Capacitors http://cgi.ebay.com/20-pcs-0-1uF-50Vdc- ... 27b328b273

20x 220 uf 16v Electrolytic Capacitors http://cgi.ebay.com/20-pcs-220uF-16V-El ... 27b329719a

5x LM386 ICs http://cgi.ebay.com/5-pcs-LM386-LM386L- ... 5ad47a6a3b

This gives you enough parts to make 2 complete LM386 audio amplifiers, and you only need to buy more potentiometers to make another 3. These particular links only total to $8.46 for all required parts.

NOW TO DEFEND TEH AMP

I know some folks say this amp is a total waste of time and sounds like utter crap. However, I have built and used this amp with a Gamecube and Genesis with good results. If anyone else has built one of these, please give some feedback on how well it worked for you.
 
I built one. Its sucked spectacularly bad. But I did scrounge all the caps and they werent quite the same as the spec'd ones.
 
samjc3 said:
I built one. Its sucked spectacularly bad. But I did scrounge all the caps and they werent quite the same as the spec'd ones.

I built one. It sucked, because I did not use the same capacitors that were in the schematic.
Click to expand...

FIX'D :evil2:

Out of curiousity, what kind of problems did you have with it, Sam? I noticed that mine got a bit distorted at high volume, but otherwise worked very well.
 
The caps I used were very close to the spec'd ones. Like 230 uf or something.

And it was just really noisy audio. There was more static than other stuff. And I dont think it was interference. I put it into a makeshift Faraday cage and it still did it.
 
My assessment of this amp is simple: if you get the right parts and don't make any mistakes, it's fantastic. It's also very finicky. But done right it can be fantastic.

SS
 
SS's approval (WOSHIP) and Hrduncan's video are enough to prove that this amp rocks.

I think the best thing to complete this easy amp would be some sort of guide on how to wire a headphone jack. I have absolutely no idea how to do that though, since I never got that far in making a portable.

Basically, I'm just asking if anyone knows how (and I'm sure it's pretty easy) then please post somethin' up!
 
I know how, I will make a new diagram sometime, although Mario's works, with the LM386 the volume is way too loud, at MR CT I found a way to make it better using resistors, I will draw them on sometime.

This works, though.

5xpgdv.jpg


SS
 
I'd also like to mention, this is best for use with 16 bit and lower systems. It's low cost, easy as pie to build ( :demonpie: ), and takes up hardly any room.

But alas, it does have a wee bit of noise when turned up to full volume, and that can be annoying sometimes. So I'm looking into making an easy-to-follow guide for the TDA2822 amp, since it looks pretty simple as well. It can do stereo, and doesn't have as much noise as the LM386 amp.
 
It always bugged me but I never bothered asking this. Why is it called the Pocket Protest?
 
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