Winners have just been announced for Hackaday’s Earth Day Challenge. We were on the lookout for projects that raise awareness of environmental issues and are happy to celebrate three top winners. Each have won a $200 shopping spree from Digi-Key who sponsored this contest.
Pictured above is the Open Flow Meter by [Eben]. The build includes sensors that are submerged into a river or stream to gauge the speed at which the water is moving. It uses a commodity plumbing flow volume sensor to help reduce costs, adding an Arduino and touch screen for reading the sensors and providing a UI to the user.
High-altitude balloons are used for air quality and weather sensing. To make those sensor packages more reusable, [Hadji Yohan] has been working on a parachute recovery system that automatically returns to a set GPS point. It’s a parafoil with auto-pilot!
Power harvesting is a fascinating and tricky game. To help ease the transition away from batteries, [Jasper Sikken] developed a solar harvesting module that charges a Lithium Ion Capacitor (LIC) from a very small solar panel. Based around a 100 uF 30 F capacitor, it uses an AEM10941 energy harvesting chip which includes Maximum Power Point Tracking (MPPT) to utilize the solar panel as efficiently as possible. The fully charged module can output regulated 2.2 V and is aimed at distributed sensor packages that can be run without any battery at all.
There’s almost always more than one way to get any particular job done. Suppose for instance you have a tank you fill up from a well, and you’d like to know when the time is right to refill the tank. The obvious answer is to measure the level of the tank, and there are plenty of ways to do that. However, [Liam Hanninen] has a different approach. Using a flow meter, he measures how much water leaves the tank. Assuming that you know it was once full, you can deduce how much water is left.
Using a YF-S201 flowmeter on a Raspberry Pi, the code uses Python to populate a database. The meter will need to be calibrated to get an exact volume measurement.
Everyone is familiar with pinwheels, and few of us haven’t crafted one from a square of paper, a stick, and a pin. Pinwheels are pretty optimized from a design standpoint, and are so cheap and easy to build that putting a pinwheel to work as an HVAC duct flow meter seems like a great idea.
Great in theory, perhaps, but as [ItMightBeWorse] found out, a homemade pinwheel is far from an ideal anemometer. His experiments in air duct flow measurements, which previously delved into ultrasonic flow measurement, led him to try mechanical means. That calls for some kind of turbine producing a signal proportional to air flow, but a first attempt at using a computer fan with brushless DC motor failed when a gentle airflow couldn’t overcome the drag introduced by the rotor magnets. But a simple pinwheel, custom cut from patterns scaled down from a toy, proved to be just the thing. A reflective optosensor counts revolutions as the turbine spins in an HVAC duct, and with a little calibration the rig produces good results. The limitations are obvious: duct turbulence, flimsy construction, and poor bearings. But for a quick and dirty measurement, it’s not bad.
Measuring air flow in an HVAC duct can be a tricky business. Paddle wheel and turbine flow meters introduce not only resistance but maintenance issue due to accumulated dust and debris. Being able to measure ducted airflow cheaply and non-intrusively, like with this ultrasonic flow meter, could be a big deal for DIY projects and the trades in general.
The principle behind the sensor [ItMightBeWorse] is working on is nothing new. He discovered a paper from 2015 that describes the method that measures the change in time-of-flight of an ultrasonic pulse across a moving stream of air in a duct. It’s another one of those “Why didn’t I think of that?” things that makes perfect sense in theory, but takes some engineering to turn into a functional sensor. [ItMightBeWorse] is using readily available HC-SR04 sensor boards and has already done a proof-of-concept build. He’s getting real numbers back and getting close to a sensor that will go into an HVAC automation project. The video below shows his progress to date and hints at a follow-up video with more results soon.
We’ve always wondered why we have indoor plumbing if it isn’t hooked up to our coffee pots. We probably drink as much coffee as water anyway, so why not just hook up a water line to refill the pot? [Loose Cannon] aka [LC] has been working on just that problem, with a whole lot of extra features, creating a very robust automatically-filled, gravity-fed, vacuum-sealed water tank for whatever appliance you have that could use it, including your coffee pot.
[LC] tapped into the 1/4″ water line from the ice maker, which has the added bonus of being a common size for solenoid valves. He’s using an eTape sensor to measure the water level in the reservoir, but he ALSO is using a flow meter in the line itself to double-check that the reservoir won’t overflow. The flow meter allows a hard limit to be set for the maximum amount of water allowed into the tank. He’s used an Arduino Micro to tie the project together, which also handles a real-time clock so the tank can be filled on a schedule.
The tank that [LC] was trying to fill was vacuum-sealed as well, which made things a little trickier. Without a vacuum on the tank, the water would just run out of the overflow valve. This is an interesting project that goes way beyond the usual automatic water supplies for coffee pots we’ve seen before.