ChipTunes Fun with NoisePlug, an ATTiny10 and a Powered Speaker from Dollar Tree

This article supplies some additional detail about a recent YouTube video I posted that shows how to build a simple "chip tunes" music player with that authentic, 8 bit sound.  The vldeo also introduces my new ATTiny10IDE, which is a complete programming environment which you use to write code for the ATTiny10 in C, C++ or assembly language.  

More on the Dollar Tree Powered Speaker module

After posting the video, I worked up a simple schematic that shows my reverse engineering version of the circuit in the Dollar Tree Powered Speaker module.  It's based on an LM4871, 3 Watt Audio Amplifier IC, which is made by Texas Instruments and sells for about $1.50 on its own.  So, the $1 I paid for the whole speaker module was a pretty good deal even if I just cannibalize it for parts.  Here's the schematic:

As noted in the video, I removed the LED, as it was hard to see, used up extra power and didn't serve a purpose, IMO.  But, there's one additional, hidden feature that I didn't cover.  The LM4871 has a shutdown pin (pin 1) which places the amp in a low power mode when the pin is placed at a high level (same as the power input voltage.)  The data sheet says this reduces the shutdown current to 0.6 microAmperes, which would make it possible to use this module in some interesting applications, such as building an Annoy-a-tron-like device that wakes up at random, or periodic intervals and plays a short, annoying sound and then goes quiet before it can be located and silenced.  To do this, pin 1 could be connected to one of the two, unused pins on the ATTiny10, such as pin 4, and then appropriate code written for the ATTiny10 to control sleeping, waking up, powering on the LM4871, paling the sound and then going back to sleep.  Leave a comment on the video if you'd like me to do a video, or article on this.

As you can see in the schematic above, this pin is permanently tied to Ground on the PCB.  The photo below doesn't show this, but there is a trace that runs under the LM4871 and connects pin 1 to pin 7, which is the ground reference pin for the IC.  So, to gain access to the showdown pin, you'd have to carefully unsolder the pin, lift it up and then use some 30 gauge wire wrap wire to make a connection to it.

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