Cloning a water-based light wall project

A few weeks ago, we featured this water-based LED graffiti art installation that allows anyone to paint in light using only a bottle of water. When one of [Chris]‘ friends saw the video of this build, he immediately asked him how it worked. One thing led to another, and now [Chris] and a few other members at the BUILDS hackerspace at Boston University are building their own water LED installation.

The basic premise of this build is allowing water to serve as a conductor between the anode and cathode of a LED. Without spraying or painting water on the circuit [Chris] whipped up, there is an infinite resistance between the two pins of the LED and current cannot flow. After applying water to the anode and cathode pads, a small amount of current is conducted through the water and the LED lights up.

Right now, [Chris] is working on a test board with different sizes of pads and spacing to get the best water graffiti LED effect for his future build. The plan is to build a single one-meter panel out of one hundred 10 cm x 10 cm boards connected together with jumpers.

All of [Chris]‘ work is up on GitHub, and even though [Chris] hasn’t begun designing the production boards, it’s more than enough to get you started if you’d like your own water LED painting panel.

Painting a wall with light using water as ink

This art installation uses a fantastic concept. The wall can be painted using water as ink which lights up a huge grid of white LEDs. This offers a very wide range of interactive possibilities since water can be applied in so many ways. Grab a paint brush, wet your finger, use a squirt gun, or mist with a spray bottle and the lights will tell you where you hit the wall.

We’re hoping a reader who speaks both French and English might help out by posting a translation as a comment on the prototyping video. In it, [Antonin Fourneau] shows off the various prototypes that led to the final product and we’d love to know what he’s saying. But by seeing the prototypes, then watching the English promo video after the break we can make a pretty good guess.  The boards have a hole that fits the flat-lens LEDs perfectly. This creates a mostly water tight seal to keep the liquid on one side while the leads are safe on the other. The water side has squiggly pads which allow droplets of water to complete an electrical connection.

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Create a laminar flow jet without pesky fiber optics.

[ApexLogic] had some PMMA core acrylic rod rod left over from a project and decided to use it as the lighting element in a laminar flow water jet.

The typical water jet consists of a bunch of sponges and drinking straws sandwiched together to slow a rough water stream and then a finely cut nozzle to provide a smooth ripple-free strand of clear water. If light is applied to this stream of water it tends to act similarly to fiber optics. [ApexLogic], however, uses a combination of shaved PVC filings, Brillo, and what appears to be most of the plumbing aisle of a local hardware store to get the same laminar flow. To top it off the polished acrylic rod is much less fragile than its glass-fiber counterpart and can have a high power light glued to the end for a nice water tight seal.

The system currently runs off of garden hose pressure, and would probably need some kind of a boost before it went into that front yard mega fountain that [Caleb] is still waiting for somebody to make.  If you still need some clarity on laminar water jets check out these videos on a few

Automatic trough filler makes sure the animals have water

It has been a hot hot summer for many parts of the US. The heat has been dangerous at times and making sure the livestock has the water they need is incredibly important. [Maddox] recently upgraded the automation on their water troughs which will help with the process. Sure, they still have to check on the animals, but this will ensure there’s plenty to drink in between those visits, and that a malfunction doesn’t waste precious water.

There has always been some level of automation here, but it relied on float valves which were frequently malfunctioning. This project seeks to get rid of the float value and use solenoid valves like those used in irrigation. These solenoids can run from a 9V battery and offer quite a bit more reliability than the mechanical vales. There is still a float sensor which measures the water level, filling up the trough when needed.

An MSP430 Launchpad was used for the prototype, from which a PCB was designed. Since this needs to be weather-proof a water tight enclosure was sourced. The company that makes the enclosure also provides DXF templates which [Maddox] used to establish the size and outline of the PCB.

High speed photography controller built to catch water droplets

One high-speed photography controller to rule them all. If you’re looking to photograph droplets of water splashing on a still reservoir this is the ticket. But if you’re not, it still offers an incredible amount of flexibility for other high-speed needs. Inside you’ll find an Arduino Mega, which has plenty of room to bend to your will.

[Michael Ross] is the man behind this box. He wanted a system that did it all; timings, droplet control, camera shutter, etc. What you can’t see in the image above is the interface panel on the back of this enclosure (this shot shows the top of the box). The video after the break will give you a look at the overall setup. It has ports to control two different light sources, detectors to snap the images using an infrared sensor or via sound (we’re thinking bullet photography), and four ports to control solenoid valves.

He produced a mammoth PDF tutorial which will guide even the biggest noob through the entire build process. Find it at his site linked above.

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Charting the efficiencies of boiling water

Water takes a lot of energy to heat up. If you’d like evidence of this, simply jump into a 50° F swimming pool on Memorial Day. Despite the difficulty of heating water, that simple act accounts for a lot of industrial processes. From cooking a steak to running a nuclear reactor, there isn’t much that doesn’t involve heating water.

[Tom Murphy], Physics prof at UCSD decided to test out exactly how efficiently he could boil water. Armed with a gas stove, electric kettle, microwave, and a neat laser pointer/photodiode setup on his gas meter to measure consumption, he calculated exactly how much energy he was using to make a cup of tea.

The final numbers from [Tom]‘s experiment revealed that a gas stove – using a pot with and without a lid on large and small burners – was about 20% efficient. A gas-powered hot water heater was much better at 55% efficiency, but the microwave and electric kettle had a miserable efficiencies of around 15 and 25%, respectively. There is a reason for the terrible inefficiency of using electricity to heat water; if only the power from the wall is considered, the electric kettle put 80% of energy consumed directly into the water. Because the electricity has to come from somewhere, usually a fossil-fueled power plant that operates at around 30% efficiency, the electric kettle method of turning dinosaurs into hot water is only about 25% efficient.

The take-home from this is there’s a lot of power being wasted every time you run a bath, make some coffee, or wash the dishes. We would all do better by decreasing how much energy we use, much like [Tom]‘s efforts in using 5 times less power than his neighbor. Awesome job, [Tom].

Floating sensor networks

These cool looking little bots are part of a fleet of floating water sensors built by The Lagrangian Sensor Systems Laboratory (LSSL) at UC Berkeley, the Lawrence Berkeley National Laboratories (LBNL) and the California Department of Water Resources.

In an emergency such as a levee break, flood, or spill, they can be deployed to gather information in a way that is completely impossible with stationary sensors. These 17″ tall bots can steer with the help of their twin props and communicate water quality information back to the base via cellular communication and short wave radio. They describe the resulting data as being like a “google traffic map” showing speed, depth, and contamination of the water.

There’s a ton of detail on their site, including breakdowns of how the software and hardware are put together. There’s even a bit of the evolution of the hardware showing the abandoned previous models.