Simple, Cheap Nitrate Tester is Open Source

Too much of a good thing can be a bad thing, and nitrate pollution due to agricultural fertilizer runoff is a major problem for both lakes and coastal waters. Assessing nitrate levels commercially is an expensive process that uses proprietary instruments and toxic reagents such as cadmium. But [Joshua Pearce] has recently developed an open-source photometer for nitrate field measurement that uses an enzyme from spinach and costs a mere $65USD to build.

The device itself is incredibly simple – a 3D printed enclosure houses an LED light source and a light sensor. The sample to be tested is mixed with a commercially available reagent kit based on the enzyme nitrate reductase, resulting in a characteristic color change proportional to the amount of nitrate present. The instrument reads the amount of light absorbed by the sample, and communicates the results to an Android device over a Bluetooth link.

Open-source instruments like this can really open up educational opportunities for STEM groups to get out into the real world and start making measurements that can make a difference. Not only can this enable citizen scientists and activists, but it also opens the door for getting farmers involved in controlling nitrate pollution at its source – knowing when a field has been fertilized enough can save a farmer unnecessary expense and reduce nitrate runoff.

There are a lot of other ways to put an open-source instrument like this to use in biohacking – photometery is a very common measuring modality in the life sciences, after all. We’ve seen similar instruments before, like a DIY spectrophotometer, or this 2015 Hackaday Prize entry medical tricorder with a built-in spectrophotometer. Still, for simplicity of build and potential impact, it’s hard to beat this instrument.

Irrighino, an Arduino Yun Based Watering System

There are many different ways to keep your plants watered on a schedule. [Luca Dentella] just created a new one by building the irrighino watering system. He used standard off the shelf, hardware to keep it simple. Irrighino is a complete watering system based on the Arduino Yun, featuring a user friendly AJAX interface. This allows scheduling in a manner similar to creating appointments in Outlook. It’s also possible to manually control the various water solenoids. The code is fully customizable and open source, with code available from [Luca’s] github repository. The web interface is divided in to three tabs – “runtime” for manual control, “setup” to configure the scheduling, and “events” to view system logs.

The Arduino Yun activates solenoid valves via a relay shield. A switch panel has indicator Status LED’s and three position switches. These allow the outputs to be switched off or on manually, or controlled via the Yun when in auto mode. [Luca] describes how to read three states of the switch (On-Off-On) when connected to a single analog input of the Arduino. He’s also got another tutorial describing how to connect a USB WiFi adapter to the Yun. This is handy since the Yun is mounted inside an enclosure where the signal strength is very weak. While the Yun has on-board WiFi, there is no possibility to attach an external antenna directly to the test SMA socket.

One interesting part is the commercial rain sensor. It’s a switch surrounded by a spongy material. When this material absorbs rain water, it begins to expand and triggers the switch. The Arduino sees the sensor as a simple digital input.

Check a short demo of his system in the video after the break.

Continue reading “Irrighino, an Arduino Yun Based Watering System”

Lighting The Great Indoors With A Solar Security Light

Look at any list of things to do to make your house less attractive to the criminal element and you’ll likely find “add motion sensing lights” among the pro tips. But what if you don’t want to light up the night? What if you want to use a motion sensor to provide a little light for navigating inside a dark garage? And what if the fixture you’ve chosen is a solar fixture that won’t quite cooperate? If you’re like [r1ckatkinson], you do a teardown and hack the fixture to do your bidding.

[r1ckatkinson]’s fixture was an inexpensive Maplin solar unit with PIR motion sensing, with the solar panel able to be mounted remotely. This was perfect for the application, since the panel could go outside to power the unit, with the lamp and PIR sensor inside. Unfortunately, the solar cell is also the photosensor that tells the unit not to turn on during the day. Armed with scratch pad and pencil, [r1ckatkinson] traced the circuit and located the offending part – a pull-down resistor. A simple resistor-ectomy later and he’s got a solar-powered light working just the way he likes it.

A simple hack, but effective. Seeing off-the-shelf gear modified is always a treat. Of course there’s something to be said for the more home-brew approach to security lighting, too.

Become a Mad Scientist, Build A Power Distribution Panel

One practical use of large switches and indicator lamps is to make a power distribution panel which can be useful when you want to control and monitor the power consumption of numerous devices such as your electronics work bench or amateur radio station. Old-school in appearance and using military surplus electronics, this power distribution panel allows for control of outlet on back. Did I mention I built it when I was 16?

Building it was easy, 120 VAC line enters through a main breaker. It is fed through an AC amp meter (with built-in shunt) then to a line filter. From the line filter it goes to a line voltage meter and filament transformer to power the indicator lamps. This AC line is then bussed out to the circuit breakers. Each breaker controls one outlet on the rear panel. As devices are switched on or off the current draw can be measured. This is well demonstrated in the video overview found after the break.

Be creative. Use military surplus switches, indicators, and other unique looking hardware. Customize to give your preferred mad scientist look while also providing valuable functionality.

Continue reading “Become a Mad Scientist, Build A Power Distribution Panel”

Wired Hive Counts Bees, Keeps Them Cozy

The world has a bee problem. Honey bees are a major pollinator for all sorts of tasty crops, but an estimated one-third of all colonies in the US have vanished since 2006. These mass disappearances are collectively known as Colony Collapse Disorder, and everything from pesticides to global warming to a new bee virus has been blamed for bees going MIA. Regardless of the cause, keeping the bees that do remain alive and pollinating is important work, and an intelligent bee hive could go a long way toward that goal.

Normally, bee hives are a black – err, white –  box, where the bees go about their business without revealing much about it. While bees are amazing animals with an incredibly rich social structure that allows them to, for instance, team together to ventilate a too-warm hive with their wings, or gang up on invading predators, they have their limits, and knowing what’s going on in the hive helps the beekeeper to maintain an optimal environment. [Miguel’s] system, which appears to still be in the prototyping phase, aims to provide the beekeeper with data on temperature and humidity within each hive. GPS tagging allows the beekeeper to track where a hive is, which is important since hives are moved around as various crops begin to flower. The system can even keep track of the comings and goings of bees using photoelectric sensors; while [Miguel] doesn’t go into detail, we imagine that aspect working something like this bee counter we featured a few years back. And being from Portugal, [Miguel] has incorporated cork into the design of the hive, a sustainable material available locally and offering great thermal properties.

Sounds like [Miguel] is onto something here. The bees need all the help they can get, and anything that improves their husbandry will go a long way toward keeping the world fed. We’ll be watching to see where [Miguel] takes this system.

Shapeshifting Material For Weather Adaptive Structures

Where [Isaac Newton] had his apple (maybe), [Chao Chen] found inspiration in a pine cone for a design project that lead to a water-sensitive building material. He noticed the way some pine cones are sensitive to water, closing up tight when it rains, but opening up with dry conditions. Some dissection of a pine cone revealed [Mother Nature’s] solution – different layers that swell preferentially when exposed to moisture, similar to how a bimetallic strip flexes when heated. [Chao Chen’s] solution appears to use balsa wood and a polystyrene sheet laminated to a fabric backing to achieve the same movement – the wood swells when wet and pulls the laminate flat, but curls up when dry.

As [Chao] points out, the material is only a prototype, but it looks like a winner down the road. The possibilities for an adaptive material like this are endless. [Chao] imagines a picnic pavilion with a roof that snaps shut when it rains, and has built a working model. What about window shutters that let air and light in but close up automatically in that sudden summer storm? Self-deploying armor for your next epic Super Soaker battle? Maybe there are more serious applications that would help solve some of the big problems with water management that the world faces.

Make sure you check out the video after the break, with a more decorative application that starts out looking like an [M.C. Escher] print but ends up completely different.

Continue reading “Shapeshifting Material For Weather Adaptive Structures”

Why Build Furniture When you can Grow it?

[Gavin Munro] is turning the standard paradigm of furniture making on its head. Instead of harvesting trees and slicing them up into boards – or worse, turning them into sawdust to be used for particle board – [Gavin] is literally growing furniture.

Supple young willow saplings are pruned and trained using wire and plastic form work. The trees are encouraged to grow in the right directions to form legs, arms, seat and back, and eventually the individual pieces are grafted Fg_3_chairs_growingtogether to continue growing into one solid piece. When the chair is mature, the leaves are removed, the chair is cut free from the ground, and with a little seasoning and finishing, you’ve got a unique and functional chair. And what’s more, since it’s a solid piece of wood, there are no joints to loosen over time.

You’ve got to admire the dedication that goes into these chairs. The current crop is about nine years old and still a few years from harvest. There’s a lot to be learned from the organization of a project like this – planning a production line where the first finished pieces are a decade or more from the showroom is no mean feat. Looks like [Gavin] has thought that through as well, by starting a line of lamps that will be turning a profit sooner. The video after the break demonstrates not only [Gavin’s] chairs and lamps, but also features his first harvest of tables.

Continue reading “Why Build Furniture When you can Grow it?”