We often lament that the days of repairable electronics are long gone. It used to be you’d get schematics for a piece of gear, and you could just as easily crack it open and fix something as the local repairman — assuming you had the knowledge and tools. But today, everything is built to be thrown away when something goes wrong, and you might as well check at the end of a rainbow if you’re searching for a circuit diagram for a new piece of consumer electronics.
But [Robson] writes in with an interesting story that gives us hope that the “old ways” aren’t gone completely, though they’ve certainly changed for the 21st century. After blowing out his laptop’s USB ports when he connected a suspect circuit, he was desperate for a fix that would fit his student budget (in other words, nearly zero). Only problem was that he had no experience fixing computers. Oh, and it takes months for his online purchases to reach him in Brazil. Off to a rocky start.
His first bit of luck came with the discovery he could purchase schematics for his laptop online. Now, we can’t vouch for the site he used (it sure isn’t direct from Dell), but for under $5 USD [Robson] apparently got complete and accurate schematics that let him figure out what part was blown on the board without even having to open up the computer. All he had to do was order a replacement IC (SY6288DAAC), and solder it on. It took two months for the parts to arrive, and had to do it with an iron instead of a hot air station, but in the end, he got the part installed.
Playing the drums is pretty hard, especially for the uncoordinated. Doing four things at the same time, all while keeping an even tempo, isn’t reasonable for most of us. Rather than hiring a drummer for your band who is well versed in this art, though, you might opt instead to outsource this job to a machine instead. It’s cheaper and also less likely to result in spontaneous combustion.
This drum machine is actually a MIDI Euclidean sequencer. Euclidean rhythms are interesting in their own regard, but the basics are that a common denominator between two beats is found in order to automatically generate complicated beats. This particular unit is running on a Teensy 3.5 and consists of four RGB rotary encoders, an SSD1306 LCD, four momentary buttons, and four 16 LED Neopixel rings. Setting each of the dials increases the number of beats for that particular channel, and it can be configured for an almost limitless combination of beats and patterns.
To really get a feel of what’s going on here, it’s worth it to check out the video after the break. MIDI is also a fascinating standard, beyond the fact that it’s one of the few remaining standards created in the 80s that still enjoys active use, it can also be used to build all kinds of interesting instruments like one that whacks wine glasses with mallets or custom synthesizers.
In this case, the light is courtesy of WS2812b LED strips. They’re a great choice, as they interface easily with most microcontrollers thanks to readily available libraries. An ESP8266 runs the show here, serving up a basic web interface over WiFi. This allows the color of the various LEDs to be controlled remotely. It also allows the lights to be switched on and off to direct whatever traffic you may be controlling. The whole project is all wrapped up in a simple cardboard enclosure, mimicking the municipal street furniture which so resolutely commands our movements.
The cardboard traffic light is a project that shows just what can be done with some off-the-shelf parts and some good old-fashioned kindergarten-style arts and crafts. If you find yourself similarly admiring these devices, check out our primer on the North American traffic signal. Video after the break.
Toys are now musical instruments. Or we’ll just say musical instruments are now toys. You can probably ascribe this recent phenomenon to Frooty Loops or whatever software the kids are using these days, but the truth is that it’s never been easier to lay down a beat. Just press the buttons on a pocket-sized computer.
One of the best examples of the playification of musical instruments is Pocket Operators from Teenage Engineering. They’re remarkable pieces of hardware, and really just a custom segment LCD and a few buttons. They also sound great and you can play real music with them. It’s a game changer when it comes to enabling musicianship.
Of course, with any popular platform, there’s a need for an Open Source copy. That’s where [Chris]’ Teensy Beats Shield comes in. It’s a ‘shield’ of sorts for a Teensy microcontroller that adds buttons, knobs, and a display, turning this into a platform that uses the Teensy’s incredible audio system designer.
When it comes to the world of microcontrollers and audio processing, the Teensy is a champ. The Teensy Audio Library has polyphonic playback, recording, synthesis, analysis, and effects, along with multiple simultaneous inputs and outputs. If you’re building a tiny synth that can fit in your pocket, the Teensy is the way to go, and [Chris]’ Teensy Beats Shield does it all, with a minimal and useful user interface. You can check out a video of the Teensy Beats Shield below.
It used to be any good electronics experimenter had a bag full of crystals because you never knew what frequency you might need. These days, you are likely to have far fewer because you usually just need one reference frequency and derive all the other frequencies from it. But how can you test a crystal? As [Mousa] points out in a recent video, you can’t test it with a multimeter.
His approach is simple: Monitor a function generator with an oscilloscope, but put the crystal under test in series. Then you move the frequency along until you see the voltage on the oscilloscope peak. That frequency should match the crystal’s operating frequency.
There are a few different ways of getting firmware onto one of AVR’s ATtiny85 microcontrollers, including bootloaders that allow for firmware to be updated without the need to plug the chip into a programmer. However, [casanovg] wasn’t satisfied with those so he sent us a tip letting us know he wrote an I2C bootloader for the ATtiny85 called Timonel. It takes into account a few particulars of the part, such as the fact that it lacks a protected memory area where a bootloader would normally reside, and it doesn’t have a native I2C interface, only the USI (Universal Serial Interface). He’s just released the first functional version for the ATtiny85, but there’s no reason it couldn’t be made to work with the ATtiny45 and ATtiny25 as well.
Timonel is designed for systems where there is a more powerful microcontroller or microprocessor running the show (such as an ESP8266, Arduino, or even a board like a Raspberry Pi.) In designs where the ATtinys are on an I2C bus performing peripheral functions such as running sensors, Timonel allows the firmware for these peripheral MCUs to be updated directly from the I2C bus master. Embedded below is a video demo of [casanovg] sending simple serial commands, showing a successful firmware update of an AVR ATtiny85 over I2C.
It’s pretty hard to use the internet to complete a task without being frequently distracted. For better or worse, there are rabbit holes at every turn and whilst exploring them can be a delight, sometimes you just need to focus on a task at hand. The solution could be in the form of distraction-blocking software, razor-sharp willpower, or a beautifully crafted modern “typewriter”. The constraint and restriction of a traditional typewriter appealed to [NinjaTrappeur], but the inability to correct typos and share content online was a dealbreaker. A hybrid was the answer, with a mechanical keyboard commanding an E-ink display driven by a Raspberry Pi.
The main point of interest in this build is the E-ink screen. Though it’s easy to acquire theses displays in small sizes, obtaining a screen greater than four inches proved to be a challenge. Once acquired, driving the screen over SPI was easy, but the refresh rate was horrific. The display takes three seconds to redraw, and whilst [NinjaTrappeur] was hoping to implement a faster “partial refresh”, he was unable to read the appropriate values from the onboard flash to enable manual control of the drawing stages. Needless to say, [NinjaTrappeur] asks if people have had success driving these displays at a more usable rate, and would love to hear from you if so.
Some auxiliary hacks come in the form of terminal emulator adaptation, porting the E-ink screen library from C++ to C, and capturing the keyboard input. A handmade wooden case finishes it off.