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Picture of 9V battery case for projects
An audio amplifier, for use between a pair of speakers and the line out socket of a computer, is fitted into the case of a PP3 (9V) battery.

The amplifier works on 12 Volts which may be tapped from inside the computer. A socket is fitted for connecting the speakers, and the input is fed in by a cable to be terminated in a stereo EP jack.

Step 1: Tpa1517 stereo amplifier

Picture of tpa1517 stereo amplifier
This is a stereo power amplifier of about 6W per channel (according to the manufacturer of the chip, Texas Instruments) which has a remarkably low component count.

The chip, two large electrolytics, and three smaller capacitors will make the amplifier complete. I am adding an output socket too, on board. The input shall be via a stereo cable and there has to be a 12 Volt supply line, as well.

The picture is of the major components arranged on a blank piece of PCB.
 
Is it a lithium 9 volt battery ?
Mic1002 years ago
Nice idea Thanks
osgeld5 years ago
small amp in a 9 volt battery casing sounds familiar (url) http://www.instructables.com/id/Pocket-Protest-a-LM386-amp-in-a-9v-battery-casing/ no worries though, I swiped the 9V battery shell idea from kipkay
Tim Temple5 years ago
The worry about opening a 9V battery is just to avoid possible lawsuits by suicidal lunatics. Those little cells inside couldn't leak unless you opened it with a sledge. They sure won't squirt. The cover was crimped down on the cells with a lot of pressure. There are those who would throw ammunition in a camp fire and try to sue for injuries incurred.
Canas5 years ago
Sounds interesting, but is it safe? It looks like you removed all of the guts from a 9v battery, but I recall Popular Science saying to not do that after a few letters received about the project. http://www.popsci.com/diy/article/2006-10/warning-regarding-nine-volt-safe
trailleadr5 years ago
Nicely done.                                                                                                                  When I first glanced at this project on the front page, I was thinking you were going to retain the 9v terminals and use another 9v to power your project. Since that would make it so you wouldn't have to worry about a battery enclosure. Obviously after reading it, a 9v battery wouldn't work as well as a direct power source from your computer for this project.