Spot This DIY Electronic Load’s Gracefully Hidden Hacks

February 28, 2019 by Donald Papp 11 Comments

Sometimes it’s necessary to make do with whatever parts one has on hand, but the results of squashing a square peg into a round hole are not always as elegant as [Juan Gg]’s programmable DC load with rotary encoder. [Juan] took a design for a programmable DC load and made it his own in quite a few different ways, including a slick 3D-printed enclosure and color faceplate.

The first thing to catch one’s eye might be that leftmost seven-segment digit. There is a simple reason it doesn’t match its neighbors: [Juan] had to use what he had available, and that meant a mismatched digit. Fortunately, 3D printing one’s own enclosure meant it could be gracefully worked into the design, instead of getting a Dremel or utility knife involved. The next is a bit less obvious: the display lacked a decimal point in the second digit position, so an LED tucked in underneath does the job. Finally, the knob on the right could reasonably be thought to be a rotary encoder, but it’s actually connected to a small DC motor. By biasing the motor with a small DC voltage applied to one lead and reading the resulting voltage from the other, the knob’s speed and direction can be detected, doing a serviceable job as rotary encoder substitute.

The project’s GitHub repository contains the Arduino code for [Juan]’s project, which has its roots in a design EEVblog detailed for an electronic load. For those of you who prefer your DIY rotary encoders to send discrete clicks and pulses instead of an analog voltage, a 3D printed wheel and two microswitches will do the job.

The No-Parts Temperature Sensor In Your Arduino

February 26, 2019 by Brian Benchoff 25 Comments

[Edward], creator of the Cave Pearl project, an underwater data logger, needed a way to measure temperature with a microcontroller. Normally, this problem is most easily solved by throwing a temperature sensor on the I2C bus — these sensors are cheap and readily available. This isn’t about connecting a temperature sensor in your Arduino. This build is about using the temperature sensor in your clock.

The ATMega328p, the chip at the heart of all your Arduino Uno clones, has within it a watchdog timer that clicks over at a rate of 110 kHz. This watchdog timer is somewhat sensitive to temperature, and by measuring this temperature sensor you can get some idea of the temperature of the epoxy blob that is a modern microcontroller. The trick is calibrating the watchdog timer, which was done with a homemade ‘calibration box’ in a freezer consisting of two very heavy ceramic pots with a bag of rice between them to add thermal mass (you can’t do this with water because you’re putting it in a freezer and antique crocks are somewhat valuable).

By repeatedly taking the microcontroller through a couple of freeze-thaw cycles, [Edward] was able to calibrate this watchdog timer to a resolution of about 0.0025°C, which is more than enough for just about any sensor application. Discussions of accuracy and precision notwithstanding, it’s pretty good.

This technique measures the temperature of the microcontroller with an accuracy of 0.005°C or better, and it’s using it with just the interrupt timer. That’s not to say this is the only way to measure the temperature of an ATMega; some of these chips have temperature sensors built right into them, and we’ve seen projects that use this before. However, this documented feature that’s clearly in the datasheet seems not to be used by many people.

Thanks [jan] for sending this in.

A Modern Solution To Tea Bag Inventory Management

February 20, 2019 by Lewin Day 13 Comments

Britain is famously known as a land of manners and hospitality. Few situations could make an Englishman’s stiff upper lip quiver, short of running out of tea bags while entertaining house guests. Thankfully, [The Gentleman Maker] is here and living up to his name – with a helpful tea monitor to ensure you’re never caught out again.

The Intelli-T, as it has been dubbed, monitors tea inventory by weight. An Arduino Uno combined with a HX711 IC monitors a load cell mounted under a canister, with a reed switch on the lid. Upon the canister being open and closed, the Arduino takes a measurement, determining whether tea stocks have dipped below critical levels. If the situation is dire, a Raspberry Pi connected over the serial port will sound an urgent warning to the occupants of the home. If there is adequate tea, the Raspberry Pi will instead provide a helpful tea fact to further educate the users about the hallowed beverage.

It’s a fun project, and one that has scope for further features, given the power of the Raspberry Pi. A little more work could arrange automatic ordering of more tea online, or send alerts through a service like IFTTT. We’ve seen [The Gentleman Maker]’s uniquely British hacks before, such as the umbrella that tells you the weather. Video after the break.

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Custom Firmware For Cheap Fitness Trackers

February 20, 2019 by Lewin Day 51 Comments

The concept of wearable hardware is an enticing one, but it can be difficult to tackle for the first-time maker. While many of us are experienced at designing PCBs and soldering up arcane gadgets, interfacing with the soft and fleshy human form can present unforeseen difficulties. There’s a way around that, of course – leveraging an existing platform where someone else has already done the work. That’s precisely what [Aaron Christophel] has done, by reverse engineering and developing custom firmware for cheap fitness trackers (Google Translate).

The first part of [Aaron]’s work consisted of research and disassembly. After purchasing a wide variety of fitness trackers online, he eventually came across his favored unit, the Tracker I6HRC by IWOWNFIT. This features an NRF52832 microcontroller, as well as an IPS display, some Flash storage, and a vibration motor. Connectivity is handled over Bluetooth Low Energy. [Aaron] particularly rates it for the well-made case that can be disassembled without damage, and the spare USB 2.0 pads on the board which can be used to program the device over the SWD interface.

[Aaron] has developed an Arduino-compatible firmware which is discussed further in a forum post. Most of the peripherals on board have been explored, and reducing power consumption is a current area of active development.

Firmware hacks are always fun – have you considered giving your TV a custom boot screen? Have a FitBit original instead of the clone? There’s a hack for that too.

[Thanks to Jim for the tip!]

Laser Light Show Turned Into Graphical Equalizer

February 13, 2019 by Bryan Cockfield 25 Comments

The gold standard for laser light shows during rock concerts is Pink Floyd, with shows famous for visual effects as well as excellent music. Not all of us have the funding necessary to produce such epic tapestries of light and sound, but with a little bit of hardware we can get something close. [James]’s latest project is along these lines: he recently built a laser light graphical equalizer that can be used when his band is playing gigs.

To create the laser lines for the equalizer bands, [James] used a series of mirrors mounted on a spinning shaft. When a laser is projected on the spinning mirrors it creates a line. From there, he needed a way to manage the height of each of the seven lines. He used a series of shrouds with servo motors which can shutter the laser lines to their appropriate height.

The final part of the project came in getting the programming done. The brain of this project is an MSGEQ7 which takes an audio input signal and splits it into seven frequencies for the equalizer. Each one of the seven frequencies is fed to one of the seven servo-controlled shutters which controls the height of each laser line using an Arduino. This is a great project, and [James] is perhaps well on his way to using lasers for other interesting musical purposes.

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Freeform Wire Frame Tulip Blooms To The Touch

February 12, 2019 by Roger Cheng 5 Comments

Holidays are always good for setting a deadline for finishing fun projects, and every Valentine’s Day we see projects delivering special one-of-a-kind gifts. Why buy a perishable bulk-grown biological commodity shipped with a large carbon footprint when we can build something special of our own? [Jiří Praus] certainly seemed to think so, his wife will receive a circuit sculpture tulip that blooms when she touches it.

This project drew from [Jiří]’s experience with aesthetic LED projects. His Arduino-powered snowflake, with LEDs mounted on a custom PCB, is a product available on Tindie. For our recent circuit sculpture contest, his entry is a wire frame variant on his snowflake. This tulip has 7 Adafruit NeoPixel in the center and 30 white SMD LEDs in the petals, which look great. But with the addition of mechanical articulation, this project has raised the bar for all that follow.

We hope [Jiří] will add more details for this project to his Hackaday.io profile. In the meantime, look over his recent Tweets for more details on how this mechanical tulip works. We could see pictures and short videos of details like the wire-and-tube mechanism that allowed all the petals to be actuated by a single servo, and the components that are tidily packaged inside that wooden base.

Need more digital expressions of love? We have no shortage of hearts. Animated LED hearts, illuminated acrylic hearts, and talking hearts. We’re a little short on flower projects, but we do have X-ray of a rose among others to accompany [Jiří]’s tulip.

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State Of The Art Big Mouth Alexa Bass

February 7, 2019 by Tom Nardi 9 Comments

Hackers seem intent on making sure the world doesn’t forget that, for a brief shining moment, everyone thought Big Mouth Billy Bass was a pretty neat idea. Every so often we see a project that takes this classic piece of home decor and manages to shoehorn in some new features or capabilities, and with the rise of voice controlled home automation products from the likes of Amazon and Google, they’ve found a new ingredient du jour when preparing stuffed bass.

[Ben Eagan] has recently completed his entry into the Pantheon of animatronic fish projects, and while we’ll stop short of saying the world needed another Alexa-enabled fish on the wall, we’ve got to admit that he’s done a slick job of it. Rather than trying to convince Billy’s original electronics to play nice with others, he decided to just rip it all out and start from scratch. The end result is arguably one of the most capable Billy Bass updates we’ve come across, if you’re willing to consider flapping around on the wall an actual capability in the first place.

The build process is well detailed in the write-up, and [Ben] provides many pictures so the reader can easily follow along with the modification. The short version of the story is that he cuts out the original control board and wires the three motors up to an Arduino Motor Driver Shield, and when combined with the appropriate code, this gives him full control over Billy’s mouth and body movements. This saved him the trouble of figuring out how to interface with the original electronics, which is probably for the better since they looked rather crusty anyway.

From there, he just needed to give the fish something to get excited about. [Ben] decided to connect the 3.5 mm audio jack of an second generation Echo Dot to one of the analog pins of the Arduino, and wrote some code that can tell him if Amazon’s illuminated hockey puck is currently yammering on about something or not. He even added a LM386 audio amplifier module in there to help drive Billy’s original speaker, since that will now be the audio output of the Dot.

A decade ago we saw Billy reading out Tweets, and last year we presented a different take on adding an Alexa “brain” to everyone’s favorite battery powered fish. What will Billy be up to in 2029? We’re almost too scared to think about it. Continue reading “State Of The Art Big Mouth Alexa Bass” →