Robust Water-Rocket Launcher Gets The Engineering Just Right

Normally when we run across a project that claims to be overengineered, we admit that we get a little excited. Such projects always hold the potential for entertainingly over-the-top designs, materials, and methods. In this case, though, we’ll respectfully disagree with [Zach Hipps] assessment of his remote-controlled soda bottle rocket launcher as “overengineered”. To us, it seems just right.

That’s not to take away from anything accomplished with this build. Indeed, we’re mighty impressed by the completeness of the build, which was intended to create a station for charging and launching air-powered water rockets. The process started with a prototype, built mainly from 3D-printed parts but with a fair selection of workshop scraps to hold it together. This allowed [Zach] to test the geometry of the parts, operation of the mechanism, and how it interfaced with the flange on the necks of 2-liter soda bottles.

Honestly, the prototype was pretty good by itself and is probably where many of us would have stopped, but [Zach] kept going. He turned most of the printed parts into machined aluminum and Delrin, making for a very robust pneumatically operated stand. We’ve got to say the force with which the jaws close around the bottle flange is a bit scary — looks like it could easily clip off a wayward finger. But if he manages to avoid that fate, such a hearty rig should keep [Zach] flying for a long time. Perhaps it could even launch a two-stage water rocket?

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Fiber Optics, But… Wetter?

Fiber optics are a great way to transfer huge quantity of data at lightning speed. Thanks to the property of total internal reflection, which allows light to flow through a glass fiber like fluid through a pipe, they can be used for communications at long distances and form the backbone of modern communication networks. However, water is also able to pull off the total internal reflection party trick, and [Mike Kohn] decided to see if it could be used as a communication medium, too.

The experimental setup consists of an ATTiny85 that receives signals over its serial port, and outputs the received bits by flashing an LED. This LED is attached to a plastic tube filled with water. On the receiving end, another ATTiny85 reads the voltage level of a photodiode placed in the other end of the tube. When the ADC detects voltage over a certain level, it toggles a pin connected to the serial RX pin.

Hooking the setup to a pair of terminals, [Mike] was able to successfully transmit 9600 baud serial data through a tube full of water with just an LED and a small microcontroller. To verify the success, he ran the test again with an air-filled tube instead, which failed. In doing so, he proved that the water was doing the work.

We’ve seen other optical data hacks, too – like this awesome laser ethernet build. Video after the break.

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Pour Yourself A Glass Of 100,000 Volts

You’d be hard pressed to find a hacker or maker who doesn’t have a soft spot for the tantalizing buzz and snap of a high voltage spark gap, but it remains the sort of project that most of us don’t take on personally. There’s a perceived complexity in building a device capable of shooting a proper spark through several inches of open air, with connotations of exotic components and massive hand-wound coils. Plus, nobody wants to inadvertently singe off their eyebrows.

While the latest video from [Jay Bowles] might not assuage anyone’s fear of performing impromptu electrolysis, it does at least prove that you don’t need to have a laboratory full of gear to produce six figure voltages. In fact, you don’t even need much in the way of electronics: the key components of this DIY Marx generator are made with little more than water and some household items.

This is made possible by the fact that the conductivity of water can be changed depending on what’s been dissolved into it. Straight tap water is a poor enough conductor that tubes of it can be used in place of high voltage resistors, while the addition of some salt and a plastic insulating layer makes for a rudimentary capacitor. You’ll still need wires to connect everything together and some bits of metal to serve as spark gaps, but nothing you won’t find lurking in the parts bin.

Of course, water and a smattering of nails won’t spontaneously generate electricity. You need to give it a bit of a kick start, and for that [Jay] is using a 15,000 volt DC flyback power supply that looks like it may have been built with components salvaged from an old CRT television. While the flyback transformer alone could certainly generate some impressive sparks, this largely liquid Marx generator multiplies the input voltage to produce a serious light show.

We’re always glad to see a new video from the perennially jovial [Jay] come our way. While his projects might not always be practical in the strictest sense, they never fail to inspire a lively discussion about the fascinating applications of high voltage.

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Compile A Hydroponics System From Source

Tending to a garden is usually a rewarding endeavor, as long as there is good soil to work with. If there isn’t, it can either get frustrating quickly having to deal with soils like sand or hard clay, or it can get expensive by having to truck in compost each year. Alternatively, it’s possible to set up systems of growing plants that don’t need any soil at all, although this requires an automated system otherwise known as hydroponics to manage water and nutrients sent to the plants.

This setup by [Kyle] is unique in that it uses his own open-source software which he calls Mycodo to control the hydroponic system. It is loaded onto a Raspberry Pi 4 (which he notes can now be booted from a USB drive instead of an SD card) which controls all of the peripherals needed for making sure that the water has the correct amount of nutrients and chemical composition.

The build is much more than just a software control panel, though. [Kyle] walks through every part of setting up a small hydroponic system capable of effectively growing 15-20 plants indoors. He grows varieties of lettuce and basil, but this system can work for many more types of plants as well. With just slight variations, a similar system can not only grow plants like these, but fish as well.

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High Voltage Experiment Pipes Power With Water

The idea of transferring energy with water isn’t exactly new. In fact, it’s downright ancient. Running water has been tapped to power our contrivances since folks were getting excited about that new library they were opening up over in Alexandria. But what if there was a way to deliver power with water that wasn’t kinetic, and instead relied on the electrical properties of the planet’s favorite libation?

That’s exactly what [Jay Bowles] set out to explore with his latest experiment. Since water (we know, not pure water) conducts electricity, it stands to reason that it could be used as a stand-in for traditional copper wiring. Why would you want to do such a thing? Because unlike wires, water can easily morph into whatever shape may be required, and can be moved around and controlled with nothing more complex than ball valves.

To test this concept, [Jay] put together a water distribution system out of simple acrylic tubing. A reservoir was attached to one of his high voltage generators, and copper caps were placed at the end of the tubes to serve as direct attachment points for devices.

But thanks to capacitive coupling, the fluorescent lights he uses don’t actually need to be physically connected to light up. As demonstrated in the video after the break, the lights surrounding the system can be independently controlled just by turning their respective valves on and off; all without any physical contact being made.

Of course, compared to traditional wiring there are plenty of downsides to this idea. Copper wires don’t tend to freeze in the winter and spring a leak, nor do they build up bubbles of explosive hydrogen gas. So it’s safe to say the wiring in your house probably won’t ever be replaced with a tube of charged water. But [Jay] does have some interesting ideas of how this technique could be used in non-traditional ways. For example, he describes how outdoor lighting could be powered by the energy radiating from a small stream.

Even if the practical applications of this technique are somewhat limited, there’s no question that it’s a fascinating idea. Believing that he’s the first person to ever demonstrate power transmission under these specific circumstances, he’s decided to call the concept “Bowles Transmission”. We’d love to see somebody use this principle in one of their projects, and we’re willing to bet so would [Jay].

As with his recent ozone sterilization experiments, we imagine this idea is going to be met with some debate. But that’s sort of the point. [Jay] doesn’t claim to have all the answers, and hopes these videos get people thinking and talking. As they say, nothing great was ever achieved without enthusiasm.

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Irrigation Controller Uses Google Calendar To Make Things Easy

Irrigation controllers have been around for a long time, often using similar hardware inside that would be familiar to the average maker. However, many of the products on the shelf at your local hardware store can be quite expensive for what amounts to a microcontroller, display, and relay board. [oscillatory] had such a rig, but wanted to bring it into the 21st century, IOT style.

The existing Holman irrigation system consisted of a control box, hooked up to four solenoid valves controlled by relays. [oscillatory] decided that replacing this with something fancier would thus be straightforward. A relay board packing an ESP8266 was sourced, and flashed with the Tasmota firmware. This was then hooked up to run off the Holman’s 24 VAC supply via a CCTV power supply, allowing the new controller to be run in parallel with the existing hardware, just in case. Scheduling is then controlled by Google Calendar, in concert with Home Assistant.

[oscillatory] now has a watering system that can be controlled over the web, and without the need to install any custom apps. Simply creating a calendar entry is enough for the system to spring into action. We’ve seen others use a similar approach, too.  It’s a great example of using off-the-shelf parts to whip up a useful custom home automation setup!

Detecting Water Before It’s Too Late

[mcu_nerd] is like any engineer, which is why his problem of an occasionally leaky water heater sure looks like a research project with no end in sight. Sure there’s probably a commercial product out there that can be had for half the cost and a few clicks of the mouse, but what’s the point in actually solving the problem?

His log starts with research into detecting low battery voltages. Then it was a quick exploration in designing low-power circuits. When the Flexible PCB contest came along, he realized that there was a chance to design a better electrode, and he ended up winning one of the vouchers; which is where he’s at now.

It’s definitely a work in progress, and if anything it’s just a quick five minute read and an opportunity to commiserate with another wayward soul. We do like his clever use of a tealite candle tin as both the second electrode and case for his water detection circuit. There are also some KiCad files and code.