Hacking out of Necessity — Fixing Your Own CPAP Machine

Fixing a CPAP machine

One of our avid readers named [Felix] suffers from sleep apnea, and needs a CPAP machine in order to not suffocate while he sleeps — After a recent power-outage, his machine broke, so he decided to try his hand at fixing it.

A CPAP (Continuous Positive Airway Pressure) machine ensures people suffering from sleep apnea breath throughout the night, by preventing their throats from closing. As a medical device, they tend to be super expensive, which is why [Felix] wanted to try fixing his (at least until he gets a new machine covered by insurance).

Upon opening up the machine, it was easy to see the problem: the circuit board was completely fried. Luckily, the machine is pretty simple. It has a brushless DC motor (12V), and two chambers with air filters, along with an air pressure sensor. Since the motor is brushless, it’s not quite as simple as just hooking it up to a power supply. It had a whopping 8 separate leads.

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Raspberry Pi Bluetooth Receiver for your Car Stereo

RasPi Car Audio

The ability to play music in your car over a Bluetooth connection is very handy. You can typically just leave your phone’s Bluetooth module turned on and it will automatically pair to your car. Then all you have to do is load up a music player app and press play. You don’t have to worry about physically tethering your phone to the car every time you get in and out of the vehicle. Unfortunately Bluetooth is not a standard option in many cars, and it can be expensive to buy an aftermarket adapter.

[parkerlreed] built his own solution to this problem using a Raspberry Pi. He first installed arch Linux on his Pi. He also had to install pulseaudio and bluez, which is trivial if you use a package manager. He then modified some of the Linux configuration files to automatically bring the Pi’s Bluetooth adapter online once it is initialized by the kernel.

At the end of the boot sequence, the Pi is configured to automatically log in to a virtual console as [parkerlreed's] user. The user’s bashrc file is then altered to start pulseaudio in daemon mode at the end of the login sequence. This allows the Pi to actually play the audio via the Pi’s sound card. The Pi’s stereo output jack is then plugged into the vehicle’s auxiliary input jack using a standard audio cable.

The Reddit post has all of the configuration details you would need to duplicate this setup. [parkerlreed] also includes some commands you will need to setup the initial pairing of the Raspberry Pi to your smart phone. Be sure to watch the video demonstration below. [Read more...]

Helix Turning Tool Born From Necessity

helix turning tool

Sometimes while working on a project there comes a point where a specialized tool is needed. That necessary tool may or may not even exist. While [Fabien] was working on his DNA Lamp project he needed to bend a copper wire into a helical shape. Every one of us has wrapped a wire around a pencil and made a little springy thing at some point. While the diameter may have been constant, the turn spacing certainly was not. [Fabien] came up with a simple gizmo to solve that problem.

The tool utilizes an 8mm rod that will ensure the ID of the helix is indeed 8mm. We’ve already discussed that was the easy part. To make certain the turn spacing is not only consistent but also of the correct amount, a wooden frame is used. The frame has holes in it to allow the 8mm rod to pass through. Adjacent to those rod holes are much smaller holes just a bit larger than the copper wire that will become the helix. These holes are drilled at an angle to produce the correct turn spacing. [Fabien] figured out the correct angle by taking the desired turn spacing distance, helix diameter and wire diameter and plopping it in this formula:

[Read more...]

Bare Bones Arduino IR Receiver

TV Remote

Old infrared remote controls can be a great way to interface with your projects. One of [AnalysIR's] latest blog posts goes over the simplest way to create an Arduino based IR receiver, making it easier than ever to put that old remote to good use.

Due to the popularity of their first IR receiver post, the silver bullet IR receiver, [AnalysIR] decided to write a quick post about using IR on the Arduino. The part list consists of one Arduino, two resistors, and one IR emitter. That’s right, an emitter. When an LED (IR or otherwise) is reverse biased it can act as a light sensor. The main difference when using this method is that the IR signal is not inverted as it would normally be when using a more common modulated IR receiver module. All of the Arduino code you need to get up and running is also provided. The main limitation when using this configuration, is that the remote control needs to be very close to the IR emitter in order for it to receive the signal.

What will you control with your old TV remote? It would be interesting to see this circuit hooked up so that a single IR emitter can act both as a transmitter and a receiver. Go ahead and give it a try, then let us know how it went!

Dodgy Hotel, Beer and A WWII Era Tube Receiver

bc-22e ww2 reciever operating in a hotel

In the luxurious accommodations provided by Motel 8 and armed only with a few tools and a six pack – a pair of amateur radio enthusiasts attempted the repair of an old WWII era BC-224E receiver. They picked up the boat anchor antique receiver, which was in unknown condition, from a flea market while in town for the Dayton Hamvention, brought it back to their hotel and got to work.

The BC-224E came in two parts – the receiver and the power supply. The speaker for the system, which is actually located in the power supply, is driven by a large inductor.  Apparently when the receiver was constructed, the permanent magnets of the day were not powerful enough to drive a speaker.

Fortunately, the receiver also came with some schematics, allowing [Gregory] and his fellow radio enthusiast to reverse engineer the power supply. After a few tweaks and cap swaps, they crossed their fingers and plugged it in. Stay tuned to see what happened next.

[Read more...]

5-Gallon 5-Piece Electronic Drum Set

electronic drums from 5 gallon buckets

Who hasn’t wanted to rock out on some drums in the middle of the night? If you have anything that resembles neighbors then a midnight jam session is out of the question. That is unless a set of electronic drums is available… but alas, those are expensive. If you don’t have the spare cash burning a hole in your pocket, then be like [Mike] and build a complete 5 piece e-drum set.

[Mike] started off with 5 gallon buckets that would become the drum shells. On a real drum set, all of the drums are different sizes in order to produce different notes. Drum size doesn’t matter with an electronic drum as a drum module creates the note and sound. Even so, to make this set a little more realistic, each drum was sectioned and pulled back together to change the diameter. A homemade circle cutting jig and a wood router were used to cut top and bottom rim hoops out of 3/4″ plywood. The inner diameter of these hoops were made just a hair larger than the outer diameter of the 5 gallon bucket shells. The bottom of the top hoop was then routed to produce a groove which would allow a standard mesh drum head to fit inside.

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A Masterpiece Of 3D Printed Case Modding. With An Ouya.


We’ve seen a few of [Downing]‘s portabalized console builds before, but this one is his first build in over two years. That’s a lot of time, and since then he’s picked up a lot of great fabrication techniques, making this one of the best looking portables we’ve ever seen. It’s a repackaging of an Ouya, but we won’t hold that against him, it’s still an amazing piece of work.

In the build log, [Downing] started off this build by using a 3D printed enclosure, carefully milled, filled, and painted to become one of the best one-off console repackagings we’ve ever seen. The speaker and button cutouts were milled out, and an amazing backlit Ouya logo completes the front.

Stuffing the Ouya controller inside a case with a screen, battery, and the console itself presented a challenge: there is no wired Ouya controller. Everything is over Bluetooth. Luckily, the Bluetooth module inside each controller can be desoldered, and slapped on a small breakout board that’s stuffed in the case.

It’s a great build, and in [Downing]‘s defense, the Ouya is kinda a cool idea. An idea much better suited to a handheld device, anyway. Videos below.

[Read more...]


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