posts tagged with the keyword ‘audio’



Around the end of 2016 I got some PCBs made that would hold ATtiny85 chips, and I used them in a sound installation. I was trying to figure out how I might reuse the piece(s) for Maker Faire Milwaukee, but I didn’t want to hang things, and I didn’t want to do the same thing again…

After I made SpringTime4 I thought about using the ATtinys in various noise-making devices, and so the journey began. (I also convinced Maks to join in and the idea for NoiseMaster 3000 was born. Oh, and along the way we recruited Dustin to join us.)


I started digging up all the speakers I could find, and grabbed lots of wall warts from Milwaukee Makerspace, and I’ve always got scrap wood on hand, so I started building. At first I just slapped things together fairly haphazardly, but as I built more devices, I started making design choices. (You’ll see these in future posts.) In this post, we’ve just got a simple noisemaker. You press a button, it makes noise. (One of the criteria we set was that everything would be momentary, so no on/off switches. Sound could only be activated temporarily, so no one could turn everything “on” and then walk away. Sound should only be present when a person was engaged with it.


In nearly all of the noisemakers I built, I chose to keep the wires and electronics exposed, or on display, as it were. If I used enclosures, they were typically open on multiple sides. Speakers were almost always visible. I didn’t stray too far from that aesthetic as I built things. Most of the buttons provided power to the unit, which started the noise, though later there were a few that used the button to enable the speaker. A subtle difference most people would not notice, but if you did, you probably know how microcontrollers work. :)


I started working on the noisemakers in June, and thought that would leave plenty of time to make a dozen before Maker Faire. I came pretty close too, and along the way ended up doing some interesting things (at least I like to think so.)

I plan to write up posts showing each noisemaker (hence the “Part I” in the title of this post.) I’ll include photos and a short video, and notes about construction.

Enjoy the Noise!

This is just one post in a series about noisemakers. Check out the other posts as well:



SpringTime4 was inspired by something my former student Maks showed me, which he called a Victorian Amp. I couldn’t find any good info on it (Oops! I should have looked up Victorian Synthesizer instead) but since I still had a large speaker left over from the Sonic Titan build I decided to build something similar.


Instead of paper clips (or solder) I used two stretched out springs to complete the circuit. This worked well, because as the speaker coil energized the top spring would bounce up and break the circuit, then fall and complete the circuit again.


To make things interactive, I added a button that could be pressed to start the device. This allowed people to interact with it, and also added another piece to complete the circuit. The whole thing is powered by a 9 volt battery, which I also left exposed, so people so see what provided power. I didn’t want a full enclosure that would appear to hide things.


I used alligator clips to connect things, which allowed for disconnecting the button unit from the speaker, which makes it a little easier to transport.


I took SpringTime4 to the Madison Mini Maker Faire and I really enjoyed watching people interact with it and then asking them if they knew what was happening. Some people sort of figured it out, and for those that didn’t quite get it, I explained how it worked. I think as a maker you tend to forget that even a really simple device can be difficult for people to understand, depending on their familiarity with things like electrical circuits.


One of my favorite parts was when an 8 year old kid tried to makersplain to me how I should improve it. It’s nice to know that even kids think they’ve got great ideas about how someone else should do things. ;)


The one improvement I’ll like to see is making it louder (if possible). It’s typical that I test things in my shop and they are fine but when I bring them into public and the environment is noisy, it’s hard to hear things. Since the visual component of seeing the springs move around is a large element of the piece, if I can’t make it louder it’s probably not a huge deal.

Here’s a short video showing SpringTime4 in action. Enjoy!


911 Phone

What looks like an ordinary desk telephone is actually part of a museum exhibit at BBCM that lets kids practice dialing 911. When they pick up the receiver they hear a dial tone, and can then dial “911″ (which plays the proper DTMF tones) they then hear the line ringing, and then an operator answers and says “911, what is your emergency?”


Inside the phone I’ve replaced the guts with a Teensy 3.2 and Teensy Audio Adaptor board. This combination handles the phone receiver being lifted, the keypad being pressed, and the playing of audio.

Teensy Pins

After consulting the docs for the Teensy Audio Adaptor board I knew which pins were used for the adaptor board, and which I could use for the receiver switch and the keypad. From what I could tell 11 pins were available (0, 1, 2, 3, 4, 5, 8, 16, 17, 20, 21) and I needed seven for the keypad and one more for the receiver switch. Plenty of pins!

I chose to go with a (perhaps slightly odd) method of having some pins point up instead of down so that I could attache female jumper wires to them. I’m not 100% happy with this solution, but it worked for this.

Teensy Wiring

The female jumper wire headers are nearly as tall as the Teeny + Audio board combined. You can also see a potentiometer used for controlling the volume, and a 1/8″ audio jack which goes to the speaker in the handset.

Receiver switch

I re-used the existing receiver switch and wired it into the Teensy. The switch is NC (Normally Closed) instead of NO (Normally Open) so I just reversed the logic in the code when looking for the switch to trigger. When the receiver is lifted the dial tone sound plays. (Also, if you leave it off the hook too long, it will play the annoying off-hook tone. (I aim for realism with this stuff!)

Keypad back

The keypad was also re-purposed (once I figured out the wiring) and wires were soldered onto the tiny thin wires, and the heat shrink tubing was added. The keypad runs to a small piece of perfboard which is used to connect to the Teensy, along with a few resistors in the mix.

Keypad Notes

Notes on how to wire up the keypad. I originally used a SparkFun Keypad for testing and development before I had a (broken) phone to tear apart.

Fritzing Diagram

Here’s a quick wiring diagram showing how it’s all put together. (I try to match wire colors in diagrams with the real-world wire colors, at least before any maintenance/repairs happen.)

Connection Board

The connector board allows for easily removing the Teensy if that’s ever required, or replacing the keypad if it goes bad. It also adds in the resistors necessary for the keypad to function properly.

Magnet Mount

For mounting the Teensy into the phone I opted to use an old hard drive magnet with a piece of wood attached. The Teensy is screwed to the wood (which is a good insulator) and the magnet is also screwed to the piece of wood, and then attaches strongly to the steel base of the phone. (There’s also gaff tape on the base of the phone, as extra protection between electricity and metal surface.)

RJ9 Wiring

I found this diagram for the speaker wiring from the handset, and wired the appropriate lines to a 1/8″ audio plug that goes into the adaptor board.

One other thing I did was add code that only accepts “properly dialed/formatted” phone numbers. So if you pick up the receiver and dial “4738911″, you didn’t dial “911″. You need to hang up and try again, with a proper “911″. There’s a buffer that looks for 3 digits (or 7 digits) and if you can’t get that right, it doesn’t work. As I said, I aim for realism with these things…

(Note: I may have left in a few numbers from testing. I’ll have to ask Jenny or Hannibal for the details.)


Yeahs! Pi!

I presented A Life Time of Yeahs! at Bay View Gallery Night but I didn’t really post much about how it was made, so I’ll do that now, as well as talk about the shortcomings. Above you can see the front and the back. The front piece is actually from an IKEA picture frame I found in the trash. It was a nice smooth MDF-like surface, so I figured it would take the vinyl and paint pretty well.

For the illustration of Mr. Rollins I did a few searches and didn’t find anything that was perfect, so I grabbed a few images as reference and traced/drew my own in Inkscape. I then created a stencil by cutting vinyl on the Silhouette Cameo (including the lettering) and stuck it all down to the IKEA board which I had already painted white.

With the vinyl in place I then painted it all flat black. I didn’t leave it all smooth as it sort of looked too polished, so I smeared some paint around with a brush and then with my fingers so it gave it some texture. I’m still not sure that was the right thing to do, but I did it, and there’s no going back.

Once I had the front piece done I found some scrap wood for the frame in my garage and cut it on the table saw. I made sure the wood was wide enough to fit the speakers into. It was, but as I’ll get to in a bit, wider would have been better…


The back of the piece contains a Raspberry Pi, a set of speakers, and a Teensy 3.0 with a few buttons connected to it. It’s all powered by a power bank from Brown Dog Gadgets.)

The speakers are USB powered so they, along with the Raspberry Pi, connect to the power bank. Turning on the power bank boots up the Pi and starts a script called “” which is a Perl script that starts running and waits for keyboard input to do something. That “something” is playing an audio file if you press the red button on the front of the piece. There’s also a small button on the back of the piece that safely shuts down the Pi if you want to turn it all off.

Yeahs! Pi!

It’s been suggested that the Teensy in addition to the Raspberry Pi is overkill, and… it is! I originally had a separate project that used some of this code and hardware and ended up just grabbing what I had lying around because it was quick and easy. Sometimes it works out that way, and that’s fine…

I should have gone with the more powerful speakers I had, because as I learned last time, if you’re doing something with audio in a public space, make it much louder than you think it should be. I had a louder pair of speakers, but they would have required AC power, so I compromised. Oh well. (You can’t tell from the photo, but there are speaker hole drilled in the side of the frame.)

I’ll probably clean up the code and publish it eventually, but essentially it gets kicked off by /etc/rc.local and runs it a continual loop waiting for a key to be pressed. If you press “a” (the button on the front) it randomly selects a WAV file and plays it. If you press the button on the back the script sees a “r” and shuts down. Why an “r” instead of an “s”? I don’t know… There’s another button that was taped up that types a “q” for quit, which quits the script, and is handy for debugging or troubleshooting if you have a monitor and keyboard attached.

That’s the summary of my Raspberry Pi based interactive painting titled “A Life Time of Yeahs!”

I hope you enjoyed it… As always, let me know if you have any questions.



In 1987 the Rollins Band released the album Life Time, which was produced by Ian MacKaye of Minor Threat, Fugazi, The Teen Idols, and of course, Egg Hunt.

The album Life Time was groundbreaking, not just in showcasing the talents of Mr. Rollins as one of the greatest screamers of all time, but in cementing into our popular culture the use of the word “Yeah!” for emphasis. You may remain unconvinced that Mr. Rollins accomplished such a thing, so I listened to the album Life Time over and over and over again. Yeah! I! Did! I then fired up my audio editing software and collected all of the best “Yeah!” moments.

Obviously you know the opening of “Burned Beyond Recognition” (the first track) starts with five consecutive “Yeahs!” and you also know that “Turned Out” ends with a massive, some would say bone-chilling “Yeah!”, but there are so many more great “Yeah!” moments. After collecting the best “Yeahs!” I culled the list to just under 50 (it was not easy!) and I’ve provided them at the push of a button for the interactive piece titled “A Life Time of Yeahs!”

Yeah! Button

I believe “A Life Time of Yeahs!” stands as a testament to the positivity that Henry Rollins exudes in everything he does. From his position as a lead vocalist to a spoken word performer, and from his portrayal as an actor to his role as a talk show host, you can expect nothing but positive “Yeah!-ness” from Mr. Rollins. If you’re feeling down, maybe you’ve got the “gun in mouth blues” or you just need someone to agree with you… Mr. Rollins and “A Life Time of Yeahs!” has got you covered.

« Older Entries | Newer Entries »

buy the button:

Buy The Button