APRS is a radio-based system for relaying various data of interest to users in the broadcasting region.
As is often the case on the PJRC forums, various other members were inspired by the project, including Malaysian ham enthusiast Stanley, who used it to upgrade their own open-source APRS Tracker, SVTrackR. rvnash’s code, as well as Stanley’s project, are available on GitHub.
Tracking indoor CO2 PPM levels emerged early in the pandemic as a way to measure one’s local environment for stale air and the increased likelihood of disease transmission. But measurements such as CO2 levels and the Air Quality Index (AQI) have also entered the public consciousness due to frequent large wildfires in recent years, and the propensity for their effects to spread well beyond their origins.
The system consists of a Teensy 3.1 connected to a Plantower PMS5003 laser particle sensor, with a small OLED display presenting time series data from the sensor. Initial test measurements showed particle pollution levels of 3-5 PM2.5, but the wildfires brought readings to 90 indoors and 380 outdoors. The resulting thread also brought out AQM projects from other forum members, as well as JBeale’s own Teensy 4.1-based evolution that uses the built-in mSD for data logging. The original sketch is available on GitHub as part of JBeale’s DataAcq collection of data acquisition tools.
Alessandro Fasan and his team of Ensoniq enthusiasts are bringing this classic synth back to life via Teensy!
The MOS Technology 6581 SID. The Yamaha OPN and OPL chips. General Instruments’ AY-3-8910. These legendary sound chips are perhaps not quite household names, but have obtained a cult following with legions of fans each declaring their allegiance to one as the superior sound generator. When the SID’s designer, Bob Yannes left MOS, he co-founded Ensoniq, and designed the 5503 Digital Oscillator Chip (DOC) at the heart of the groundbreaking Ensoniq Mirage sampler synth.
The ALFASoniQ Mirage II began development a Teensy 3.5 coupled with Erturk Kocalar’s Retroshield 6809 housing the DOC (Digital Oscillator Chip). The system is capable of booting the alternative Mirage operating system MASOS 3.2 from SD, and while not all of the voices and modes are functional, full polyphony is supported. Source code can be found on GitHub, while the video below gives a demonstration of the project’s state.
More recently, the ALFASoniQ has moved to development on Teensy 4.1 with software emulation of the 6809 chip. This quick video demos show the project’s progression to utilizing the more powerful hardware to implement more Ensoniq capability.
Step sequencers have been around since at least the 1960s, and from the 1980s and beyond became a very common sight as the number and variety of digital instruments exploded.
This DIY Drum Machine from Robert Robert on YouTube is a unique blend of the two, with a huge number of switches and knobs up front, but a Teensy 3.6 and Audio Adaptor Board generating the beats behind the scenes.
Most step sequencers have 16 buttons with LEDs to indicate on/off status, which are reused in order to create multiple tracks and thus produce layered sounds. This device has a dedicated row of 16 switches for each of its ten tracks/samples, with 16 LEDs above them to indicate which note in the sequence is currently playing. Momentary switches on each row allow the same samples to be triggered at any time, and 10 potentiometers allow the volume of each sample to be adjusted, also effectively allowing a track to be muted. Four additional buttons and knobs allow a further four samples to be triggered at corresponding volumes. A 16×2 I2C LCD display and further knob allows configuration of parameters such as BPM. See it in action and learn more about its construction in the video below!
The Arcom RC210 Advanced Repeater Controller is a popular solution for managing multiple amateur radio repeaters. It has a built-in real-time clock (RTC) for scheduling and other features, but extended power outages and other factors can cause it to drift.
MatA came up with a great solution to this problem in the form of their GPS Time Source project.
Initially based on an Arduino, MatA switched to the Teensy LC on recommendation from a friend, greatly enhancing the project’s capabilities thanks to increased memory and processing power over the original. A custom PCB holds the Teensy, GPS module, LCD display, and DB9 connectors for interfacing to the repeater controller. Find out more on the project’s web page.
The idea of aeroponics — growing plants in an air or mist environment rather than soil — has been around for over a century, yet somehow it always appears very high-tech and novel in practice.
The system uses a custom PCB, which incorporates an LM2596S buck converter and TI P82B715DR I2C extenders to give the humidity sensors further reach. The TI HDC1080 low-power digital relative humidity sensors used have a single hard-coded I2C address, so an Analog Devices LTC4316CDD#TRPBF I2C address translator is used to allow them to coexist on the same bus. After creating a successful aeroponic monitoring system, boomish went on to create a SQL-backed hardwood floor humidity monitoring and logging system, with the exciting additional feature of Power over Ethernet (PoE).
ThinkPad keyboards and TrackPoint pointing devices are somewhat legendary, with many connoisseurs preferring older IBM models to current Lenovo products.
The project consists of a custom PCB, in order to provide the required connectors, an Analog Devices AD8236 Instrumentation Amplifier reading each channel of the strain gauge, and TI LM358 op-amps providing a reference voltage. Code and documentation can be found on GitHub, with additional detail on Hackaday, and a detailed overview in the video below.
We love to see ham and software-defined radio (SDR) projects. K7MDL discovered the Teensy-based KeithSDR project and effectively forked it with a plethora of enhancements including a color touchscreen and illuminated rotary encoders for a beautiful finished build.
Various implementations allow the device to be used as a receiver, panadapter, or control head over Ethernet. Particular attention was paid to performance with the Bit Transfer Engine (BTE) functionality of the RA8875/RA8876 controller being leveraged to provide smooth scrolling of the spectrum and waterfall without taking CPU cycles away from the Teensy 4.1.
A custom UI framework and gesture engine provide a highly-optimized user experience. Example builds and an extensive wiki can be found on GitHub, with even more pictures and detail on Mike’s blog.
1bit shares the TELEZ BioReactor Controller project. Teensy runs a collection of pumps, HX711-based load cells, and associated I/O in a 3U rack.
This homebrew solution replaces about $1200 of Siemens hardware, with the added bonus that users will be able to monitor the bioreactor remotely using a custom Android app, thanks to the addition Particle Electron providing cellular data.
Everybody* loves rhythm games, and everybody* loves roller coasters, which is why the two were combined so gloriously in the unique arcade game Groove Coaster.
Consisting of a Teensy 3.2, two Seimitsu LS32-SE joysticks, two giant 60mm buttons, some 3d-printed parts, a plywood box, and some simple hardware to hold it all together, the result is an incredible likeness of the unique arcade interface. CAD files, code, BOM, and assembly instructions can all be found in the GitHub repo!
*OK, maybe not everybody, but it sounds better that way!
