Recharged Dehumidifier Put Back Into Service

September 19, 2021 by 37 Comments

For the average consumer, repairing relatively low-cost home devices such as microwaves and TVs just isn’t economically viable. You can hardly blame them when the repair bill could easily be higher than the cost of just buying a new model. Luckily for folks like us, that means you can often find cheap or even free appliances on the second hand market that can be brought back online with a bit of troubleshooting and some spare parts.

Take for example the non-functional dehumidifier [HowToLou] recently came across. You probably couldn’t find a professional repair shop that would be willing to bother with one of these things if you tried, but as he shows in the video below, that doesn’t mean the DIY’er can’t run through some probable failure modes and get the unit back up and running. As a bonus, he also walks viewers through how your typical compressor-based dehumidifier operates.

The failed thermal switch.

Beyond the lack of water in the collection compartment, the first sign that something was wrong with this dehumidifier was that the compressor wasn’t running. Upon closer inspection, [HowToLou] determined that the thermal cut-off switch had failed and was stuck open. Luckily it had a visible part number so he could order a replacement, and in the meantime, all he had to do was cut the switch out of the circuit and wire up the compressor’s power directly.

Unfortunately, even with the compressor running, no water was being collected. Noticing that the evaporator coils weren’t getting very cold, [HowToLou] thought the unit might be low on refrigerant. Usually these systems aren’t meant to be recharged, but with a clever piercing tap valve, you can add a quick-connect port to the low pressure side. This particular dehumidifier happened to be filled with the same R134a used in automotive A/C systems, so a quick trip to the auto parts store got him a can of refrigerant complete with a handy pressure gauge.

After getting juiced up, [HowToLou] shows ice forming on the coils and plenty of water getting dumped into the tank. Automotive A/C refill cans usually include some substance to stop or reduce leaks in the system, so hopefully this will end up being a long-term fix. It might not be the most elaborate dehumidifier repair we’ve ever seen, but it’s certainly the most approachable. If you ever see one of these things laying on the side of the road, maybe you should pick it up and see what ails it.

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A musical cyberdeck

Musical Cyberdeck Is Part Synth, Part MIDI Controller, And All Cool

September 9, 2021 by 3 Comments

When a new project type starts to get a lot of exposure, it’s typically not long before we see people forking the basic concept and striking out in a new direction. It happened with POV displays, it happened with Nixie clocks, and now, it seems to be happening with cyberdecks. And that’s something we can get behind, especially with cyberdecks built to suit a specialized task, like this musical cyberdeck/synth.

Like many musicians, [Benjamin Caccia] felt like he needed a tool to help while performing with his band “Big Time Kill.” He mainly needed to trigger track playbacks on the fly, but also wanted something to act as a mega-effects pedal and standalone synth. And while most of that could be done with an iPad, it wouldn’t look as cool as a cyberdeck. The build centers around a Raspberry Pi 4 and a 7″ LCD display. Those sit on top of a 25-key USB MIDI keyboard and a small mixer. Alongside the keyboard is a USB keypad, which has custom mappings to allow fast access to buried menu functions in the cyberdeck’s Patchbox OS. Everythign was tied together on a 3D-printed frame; the video below shows it in action, and that it sounds as good as it looks.

We think [Benjamin]’s cyberdeck came out great. Need to see some other specialized cyberdecks? Why not take a look at this battle-ready cyberdeck, one that aims to be distraction-free, or a cyberdeck for patrolling the radioactive wastelands.

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MIDI Mouse Makes Marvelous Music

July 18, 2021 by 5 Comments

It’s an old misconception that digital musicians just use a mouse and keyboard for their art. This is often far from the truth, as many computer music artists have a wide variety of keyboards/synths, MIDI controllers, and “analog” instruments that all get used in their creative process. But what if one of those instruments was just a mouse?

Well, that must have been what was going through [kzra]’s mind when he turned an old ps/2 roller ball mouse into an electronic instrument. Born out of a love for music and a hate for waste, the mouse is a fully functional MIDI controller. Note pitch is mapped to the x-coordinate of the pointer, and volume (known as velocity, in MIDI-speak) is mapped to the y-coordinate. The scroll wheel can be used as a mod wheel, user-configurable but most often used to vary the note’s pitch. The mouse buttons are used to play notes, and can behave slightly differently depending on the mode the instrument is set to.

Not satisfied with simply outputting MIDI notes, [kzra] also designed an intuitive user interface to go along with the mouse. A nice little OLED displays the mode, volume, note, and mouse coordinates, and an 8×8 LED matrix also indicates the note and volume. It’s a fantastic and versatile little instrument, and you’ve gotta check out the video after the break to see it for yourself. We’ve seen some awesome retro-tech MIDI controllers before, and this fits right in.

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MIT’s Knitted Keyboard Is Quite A Flexible MIDI Controller

June 30, 2021 by 7 Comments

There are only so many ways to make noise on standard instruments such as acoustic pianos. Their rigidity and inputs just don’t allow for a super-wide range of expression. On the other hand, if you knit your interface together, the possibilities are nearly endless. MIT’s new and improved knitted keyboard is an instrument like none other — it responds to touch, pressure, and continuous proximity, meaning that you can play it like a keyboard, a theremin, and something that is somewhere in between the two. Because it’s a MIDI interface, it can ultimately sound like any instrument you’ve got available in software.

The silver keys of this five-octave interface are made of conductive yarn, and the blue background is regular polyester yarn. Underneath that is a conductive knit layer to complete the key circuits, and a piezo-resistive knit layer that responds to pressure and stretch. It runs on a Teensy 4.0 and uses five MPR121 proximity/touch controllers, one per octave.

The really exciting thing about this keyboard is its musical (and physical) versatility. As you might expect, the keyboard takes discrete inputs from keystrokes, but it also takes continuous input from hovering and waving via the proximity sensors, and goes even further by taking physical input from squeezing, pulling, stretching, and twisting the conductive yarns that make up the keys. This means it takes aftertouch (pressure applied after initial contact) into account —  something that isn’t possible with most regular instruments. And since this keyboard is mostly yarn and fabric, you can roll it up and take it anywhere, or wrap it around your neck for a varied soundscape.

If you’re looking for more detail, check out the paper for the previous version (PDF), which also used thermochromic yarn to show different colors for various modes of play using a heating element. With the new version, [Irmandy Wicaksono] and team sought to improve the sensing modalities, knitted aesthetics, and the overall tactility of the keyboard. We love both versions! Be sure to check it out after the break.

Want to play around with capacitive touch sensors without leaving the house for parts? Make your own from paper and aluminum foil.

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Turning GameCube & N64 Pads Into MIDI Controllers

June 19, 2021 by 2 Comments

It’s fair to say that the Nintendo 64 and GameCube both had the most unique controllers of their respective console generations. The latter’s gamepads are still in high demand today as the Smash Bros. community continues to favor its traditional control scheme. However, both controllers can easily be repurposed for musical means, thanks to work by [po8aster].

The project comes in two forms – the GC MIDI Controller and the N64 MIDI Controller, respectively. Each uses an Arduino Pro Micro to run the show, a logic level converter, and [NicoHood’s] Nintendo library to communicate with the controllers. From there, controller inputs are mapped to MIDI signals, and pumped out over traditional or USB MIDI.

Both versions come complete with a synth mode and drum mode, in order to allow the user to effectively play melodies or percussion. There’s also a special mapping for playing drums using the Donkey Konga Bongo controller with the GameCube version. For those eager to buy a working unit rather than building their own, they’re available for purchase on [po8aster’s] website.

It’s a fun repurposing of video game hardware to musical ends, and we’re sure there’s a few chiptune bands out there that would love to perform with such a setup. We’ve seen other great MIDI hacks on Nintendo hardware before, from the circuit-bent SNES visualizer to the MIDI synthesizer Game Boy Advance. Video after the break.

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Old Phone Becomes MIDI Controller

June 9, 2021 by 5 Comments

MIDI controllers come in all shapes and sizes. Commercial products based on keyboards or matrixes of buttons are popular, but there’s nothing stopping you from whipping up your own creations out of whatever strikes your fancy. [Kevin] has done just that, turning an old telephone into a working MIDI device.

The phone in question is a Doro X20 wired landline phone. Being surplus to [Kevin’s] requirements left it ripe for the hacking. A Raspberry Pi Pico was wired in to the phone’s keypad, slimmed down with a hacksaw in order to allow it to neatly fit inside the original enclosure. Then it was a simple matter of whipping up some code to read the buttons and output MIDI data via the Pico’s serial output.

Later, [Kevin] brought the design into the modern world, setting it up to talk USB MIDI using the Pico’s onboard USB hardware. This makes using it with a computer a cinch, and lets [Kevin] control a DAW using the handset controller.

It’s a fun build, and one that shows how you can easily build your own MIDI hardware using nothing but a soldering iron, some buttons, and a modern microcontroller. From there, the sky really is the limit. Whether you like big knobs, easy playing, or have your own personal tastes, you can build what you like to suit your own style. When you do, drop us a line! Video after the break.

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A MIDI Controller — From A Twister Mat?

May 9, 2021 by 3 Comments

Twister, the mildly embarrassing but strangely enjoyable floor contortion game that most of us have vague youthful memories of from Christmas parties. Could a Twister mat be used as an input device? [Guy Dupont] took those 24 coloured dots and made just that, after a conversation with a friend.

Wiring up a floor-sized plastic mat isn’t as easy as it might seem, and early experiments with copper foil and capacitive touch sensor chips proved to be a failure. The replacement came in the form of force sensitive resistors, read by a brace of MCP3008 multiplexed analogue-to-digital converters. These are then read by an ESP32 that does all the MIDI magic. We’re treated in the video below the break to full details including the entertaining sight of him playing Twister to a beat, prompted by a robotic-voiced random move generator, and we can see that this devices has some potential.

We’ve not seen another Twister mat before, but force sensitive resistors have made an appearance in a much higher-resolution array. It’s the LED floor game controller that has us going though.

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