It happens to the best of us. You design a board. Wait for the board. Get the board. Assemble the board. Board doesn’t work.



I put the board together, but I ran out of those nice little yellow 22 pF caps that I get from SparkFun. I jammed another 22 pF cap in there just to try it out. Sadly, the board doesn’t work. Looking back over the schematic, I see why. Stupid design errors! I don’t know what I was thinking. I can’t even begin to rework the board. It’s just beyond.



It’s looks nice, right? Too bad it’ll never work. Besides the embarrassment of missing a Vcc connection on the board, I omitted a very important 100 ohm resistor on the speaker. I also have a cap going to Vcc when it should be going to ground. I really don’t know what I was thinking when I made this board. I thought I double checked everything. Forest for the trees? Who knows?

I had the whole weekend to wrap this up, so the boards being DOA really put a cramp in my plans to finish it. I even picked up a nice box for it as well as one of those cool arcade buttons from SparkFun.



I decided to forget a custom PCB and just assemble it on a protoboard. I have a few of these little gems that I bought from RadioShack years ago. Looks like today’s that rainy day!



I threw the ATmega on there. Pretty easy. I also added an LED to a digital pin so I could throw the blink sketch on there just to make sure it works.



Powered it up….BOOM! Good to go.



I then added the LM386...



…and a speaker.



It probably took me an hour to throw it together. But again, I’m not happy with it. It’s still just not loud enough! It’s weird. I can play simple tones through it and it’s plenty loud enough, but the fart sounds aren’t loud at all. Must be a PWM thing.



I messed around with the caps and resistors to see if I could make it sound better. Although the gain is at max, I just don’t think it’s going to be loud enough once it’s in the enclosure. I decided to maybe just ditch the LM386 all together and pickup the TPA2005D1 audio amp breakout board that SparkFun sells. (It’ll probably make for a cleaner build too.)

Instead of making a dedicated PCB for the SoundBox, I’m kicking around the idea of making a multi-purpose bare bones Arduino PCB. It’ll also come in pretty handy for future projects too. It’s basically an ATmega with the pins broken out. I’ll install headers so I can make it reusable; that way I can also prototype with it. Optionally, I can forgo the headers and just solder directly to it and make it a final project. It’ll be nice to have a few of these around for when I want to just quickly throw something together.



It’s also half the size!



I can get 3 from OSH Park for about $12. Sounds good to me. I’ll finish this fart box one day!

See this project from start to finish:
The FartBox
Staples Easy Button
SoundBox PCB
SoundBox Boards Are a Bust!
Completed the SoundBox