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Electronics help...

o0ICE0o

o0ICE0o

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Not exactly laser related, but this seems to be the best place to put this... and you guys are good with electronics; so...

Long story short, I am modding a Game Boy Advance SP, by melding it with a PlayStation 2 controller for buttons, and adding speakers.

I have run into a problem...
I need an amplifier, or two, to power both of the speakers.
It is 2 channel stereo.

The GBA's battery is 3.8 v.

I need a circuit that would amplify the signal(s) from the 3.5mm audio jack.

I googeld, but got nowhere.
Thank you. :eek:

(Also, I have been gone for a short time, but the BRs are already in the 12x-s!! :drool: )

EDIT: The back of both of them say: 8 (Ohm) IL 271N-1
They are about 1 inch in diameter.
 
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photonaholic

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LM386 low voltage audio amplifier IC.

I think Radio Shack still carries them, or DigiKey certainly has them.

I just looked, $1.49 each at radio shack.

Simple hookup with a breadboard.
 
o0ICE0o

o0ICE0o

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...So two of these, one for each channel?

can I add a potentiometer to change the volume?
If so, is it before this IC, or somewhere between the pins?
How would I set this up to controol both IC's at the same time?

(THANKS!)
 
photonaholic

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o0ICE0o said:
...So two of these, one for each channel?

can I add a potentiometer to change the volume?
If so, is it before this IC, or somewhere between the pins?
How would I set this up to controol both IC's at the same time?

(THANKS!)
Click to expand...


I'll post a picture and schematic for you in the morning.

yeah, they are single channel about 1 watt output.
 
o0ICE0o

o0ICE0o

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Thank you very much for all of this help - I would have never found this on my own. ^_^
(goodnight, lol)
 
o0ICE0o

o0ICE0o

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What is the minimum set up that this can use?
The space in the remote is very limited.
 
photonaholic

photonaholic

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about 1 inch or so cubed (the 250uf cap is kinda tall)

why not put in a small jack for say a set of PC speakers off to the side? or better yet, headphones?
 
o0ICE0o

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I still want it to be portable, and the holes for the joysticks that are no longer there would be perfect for speakrs, and i have two that fit.
1x1x1 would probable be do-able, with some awsome "boardless sodering".
 
o0ICE0o

o0ICE0o

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Sorry for the double post...

What are the BARE MINIMUM components that this needs to operate?
After this, are there any that would make this work better, with a very small impact on the size?

Thank you. I would figure this out myself, but I am not good with circuits.
I can solder them together very well, but not really figure out how to make them.
:/
 
photonaholic

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I re read those schematics, that is the bare minimum of parts, I can squeeze that on a stamp size PC board.
 
o0ICE0o

o0ICE0o

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Oh.

Ok, then.

Thank you for all of your help!
It just looked like a lot to be the minimum.

I miss-assumed.

If I ever finish this project, I will post back here.
:D

EDIT:
Oh, WOW!
"Fig 1: LM386 Audio Amplifier with Gain = 20 and minimum part count"

Thats what I gut for using a ridiculous resoloution... small text is small, lol.
I didn't really look at those circuts...



lm386-20.gif



...To make shure:
Is Vin the battery, and Vs is the signal to amplify?
Or is it the other way around?
Also, pins 1,7, and 8 are just open?
Finlay, pin 3 gets connected before, or after the resistor?

Wow. I just hardcore newb-d. :(
 
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o0ICE0o

o0ICE0o

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...I should have aksed this earlier, but what does the "not needed" part do if it's there?
What happens if it is not?

THANK YOU!
 
photonaholic

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it's there to block low frequency noise. (its a "hum" filter)

I have built these without that (the hum filter) and they worked fine.

.05 uf is a tiny disc cap, it will only conduct very low frequency signals, then shunt them through the 10 ohm resistor.

Like a bandpass blocking filter.
 
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