Pocket Protest Audio Amp - LM386

I'm wondering if someone could help on this. I followed the diagram above and hooked the amp up to a 7.4v line but I get absolutely nothing sound wise when I turn on the N64 I've attached it too.

Heres a couple of pics of the amp I built:

IMG_0324.jpg


IMG_0325.jpg


now the only difference in the parts I used listed was that I used a 220UF 25v cap instead of a 16v one.

I've also checked that power is getting to the amp but I just can't figure out why I get no sound whatsoever? :mad:
 
Because you've got both pins of the speaker connected to the same leg of the capacitor. I looked at the diagram and there's no clear spot marked where to positive leg goes, but they never go to the same spot.
 
bentomo said:
Because you've got both pins of the speaker connected to the same leg of the capacitor. I looked at the diagram and there's no clear spot marked where to positive leg goes, but they never go to the same spot.

Thanks for the heads up. So any ideas as to how to wire the speaker then? one wire to common ground and the other to the cap? :confused:
 
Any chance you could include how you wire a headphone jack with speaker switch off when headphones are plugged in SS?
 
Would this work?

headphone.jpg


Basically running an audio input from the amp to both sides of the headphone jack so that when the headphones are plugged in the connection is broken to the speaker and then feeds from the other audio input.
 
Built one today. Got nothing. Speaker is connected to the positive and negative poles if the capacitor respectively. Amp is getting 4.99v from the n64s 7805. Both audio channels are connected to the same line. Funny thing is the potentiometer controlled the audio from the tv when I had the n64 connected to the amp and a tv at the same time. :lol:
 
budnespid said:
Built one today. Got nothing. Speaker is connected to the positive and negative poles if the capacitor respectively. Amp is getting 4.99v from the n64s 7805. Both audio channels are connected to the same line. Funny thing is the potentiometer controlled the audio from the tv when I had the n64 connected to the amp and a tv at the same time. :lol:

Nay, you're doin' it wrong. Negative on the speaker goes to common ground, positive on the speaker goes to negative on that cap.

SS
 
Figured this might be worth throwing in there:

386_schem_engadget_howto.jpg


Different way to wire it up, this is Ben's diagram.
Benheck wired up two of these and used a dual potentiometer to get stereo sound in his Wii Laptop.

SS
 
Alright, this is one I wired up today:

audioampmajora.jpg


As you can see, this thing can get pretty tiny.

Note: Don't use a GC slider for your 10k pot, it sounded terribad. The 10k pot actually affects how the sound, uh, sounds, I had to change to a different one, then finally a trimmer. That said, all of mine were scrap ones, so if you actually buy a good one then you'll be fine. :sscool:

Now then, if you were to, oh, I don't know, wire up a headphone jack straight to this amp?
You'd blast your ears out.
The amp is designed to drive a speaker, not headphones.

It's best to have a resistor on the headphone jack in order to make it quieter, but you can't just add one, because you'd be adding a resistor to the speaker as well, making it quieter. You have to take advantage of the switching that goes on in the headphone jack.

I figured this out at MR CT, then Wyatt ate the amp and I didn't build one of those amps again till recently I guess. :dah:

The resistor shown is a 10k one, but I stepped it waaay down to a 100 Ohm and it sounded fine. It depends on your preference, you can make it as regulated or unregulated as you want, Heck, you could ever have another pot on this line so you can adjust it at will. XD

This only works for mono input, I think. It's wired so you get mono sound in both ears though.

headphonejackmono.jpg


Do exactly that, and you get full amp output to the speaker, and regulated output to the headphones.

SS
 
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