E-Ink Equipped Sourdough Starter Jar

One of the unexpected side effects of our this pandemic is a sudden growth in the global population of captive colonies of Lactobacillus bacteria and yeast. Also known as sourdough starters, they are usually found in jars with curious names written on top, living off a mixture of flour and water. They require close monitoring to keep them healthy and to determine when they are ready for baking. [Noah Feehan] has been working to instrument and automate the process for the past two years, and has created a high-tech jar to keep an eye on his sourdough starter.

For a sourdough starter to stay active, it must be kept within a certain temperature range, and performance is measured by how much the level inside the jar rises. Existing open source and commercial projects monitor these two parameters and transmit data out, but [Noah] wanted to include a few more features. The height of a sourdough starter rises due to the production of CO2, so he added an SCD-30 sensor module, which includes a temperature and humidity sensor. For level monitoring, an VL6180 time-of-flight sensor is mounted over a hole on top of the jar. [Noah] wanted to be able to see recent CO2 production and height stats right on the jar, a ESP32 module with onboard E-ink display was used. To draw air over the CO2 sensor at a constant rate, a small extraction fan was also added. Power is provided by a small LiPo battery. For long term logging, the data is sent over MQTT to a server running Mycodo environmental regulation software.

There are still several software improvements [Noah] would like to make, including battery life, user interface and alerts, but everything is open-source and available on GitHub, so feel free to jump in and build your own.

Lidar House Looks Good, Looks All Around

A lighthouse beams light out to make itself and its shoreline visible. [Daniel’s] lighthouse has the opposite function, using lasers to map out the area around itself. Using an Arduino and a ToF sensor, the concept is relatively simple. However, connecting to something that rotates 360 degrees is always a challenge.

The lighthouse is inexpensive — about $40 — and small. Small enough, in fact, to mount on top of a robot, which would give you great situational awareness on a robot big enough to support it. You can see the device in action in the video below. Continue reading “Lidar House Looks Good, Looks All Around”

Lazydoro Mothers You Into Being Productive

The Pomodoro Technique has helped countless people ramp up their productivity since it was devised in the late 1980s. Breaking down tasks into 25 minute chunks can improve your focus tremendously, provided you show up, start the timer, and get to work.

Lazydoro takes the psychology focus even further. In [romilly.cocking]’s interpretation, a time-of-flight (ToF) sensor is your productivity Santa Claus — it knows whether you’re doing your part by simply applying butt to chair, and your present is a productive 25 minutes where not a second is wasted futzing with timers and worrying about time lost to such administrative tasks. When Lazydoro senses that you have arrived, the Raspi Zero starts a 25-minute Pomodoro timer, and represents the time remaining across a Pimoroni BLINKT LED matrix.

But hold on, you haven’t heard the best part yet. Lazydoro was designed with real life in mind, because [romilly] thought of everything. Whenever you leave your chair, a 5-minute timer starts, and there’s a beep when time is up. If you make it through the 25 minutes and hear the victory beep, then it’s break time. But if you get up too soon, the work timer stops, and the 5-minute timer becomes your limited space in which to fret, stare out the window, or get the snack you think you desperately need to keep going. This makes Lazydoro awesome even without the Pomodoro part, because simply sitting back down is a big step one.

If you make a circuit sculpture Pomodoro and stare at it on your 5-minute breaks, you might achieve productivity enlightenment.

Laser Trip Wire Hides What You’re (Not) Working On

We assume your office policy allows for reading Hackaday during work hours. But what about cruising reddit, or playing Universal Paperclips? There’s a special kind of stress experienced when attempting to keep one eye on your display and the other on the doorway; all the while convinced the boss is about to waltz into the room and be utterly disappointed in you.

But fear not, for [dekuNukem] has found the solution with Daytripper. This wireless laser tripwire communicates back to your computer using NRF24 (2.4 Ghz on the ISM band) and can be used to invisibly cordon off a door or hallway and fire a scripted action on your computer if its beam has been broken. Nominally this is used to send the keyboard command that hides all open windows, but we’re sure the imaginative readers of Hackaday could come up with all sorts of alternate uses for this capability.

The Daytripper transmitter uses a laser time-of-flight sensor, in this case the very small VL53L0X by STMicroelectronics. It’s best situated so the laser will be bounced straight back at it. It has a range of about four feet, which is perfect for covering a door, though a wide hallway could give it some trouble. [dekuNukem] admits that the 5 Hz scan rate means a sufficiently fast moving adversary might slip past the sensor, but if they’re trying that hard to see what’s on your monitor, they probably deserve a peek.

On the receiver side, there’s a small board that plugs into your computer and mimics a USB keyboard. It has a selector switch on the side that allows the user to set what key sequence will be “typed” once the system has been tripped. It has built-in support for minimizing all windows or locking the computer, or you can set it to send ALT + Pause, which you can listen for and act on however you see fit.

If you want to build your own Daytripper, the firmware and hardware are both available on GitHub under an MIT license. For those who prefer instant gratification, [dekuNukem] is doing a small production run and offering them up on Tindie.

Determining Kibble Level Via Time-of-Flight

[WTH] is building an IoT kitty food dispenser. There are a few of these projects floating around that measure out portions very sensibly — some use screws to dispense a set amount of food at a time, some measure the weight of the remaining stockpile. This build is definitely not that. This kitty food monitor uses a time of flight sensor to determine the remaining level of food in a hopper. [WTH]’s feeder lets the cat eat all the grub it wants, then alerts the hooman when kibble levels drop below a certain level.

The project starts with one of those pet food dispensers that consist of a hopper that gravity feeds into the food bowl. As the animal eats that food, more dispenses into the bowl. Attached to the lid is an ESP8266 connected to an Adafruit time of flight sensor. This reports the kibble level in centimeters, which is good enough for [WTH]’s purposes. Sensor data is logged to a Google Drive spreadsheet, published as a graph through M2X (AT&T’s IOT service), and texted to [WTH]’s smart watch via IFTTT.

Look for a plethora of Tweeting, Instagramming, and otherwise automated feeding of the cat overlords right here on Hackaday. Check out automatic cat feeder dispenses noms, wants cheezburger, and a cat feeder made with laminator parts.

Testing Distance Sensors

I’m working on a project involving the need to precisely move a tool based on the measured distance to an object. Okay, yeah, it’s a CNC mill. Anyway, I’d heard of time of fight sensors and decided to get one to test out, but also to be thorough I wanted to include other distance sensors as well: a Sharp digital distance sensor as well as a more sophisticated proximity/light sensor. I plugged them all into a breadboard and ran them through their paces, using a frame built from aluminum beams as a way of holding the target materials at a specific height.

Continue reading “Testing Distance Sensors”