Generating Random Numbers With A Fish Tank

While working towards his Computing and Information Systems degree at the University of London, [Jason Fenech] submitted an interesting proposal for generating random numbers using nothing more exotic than an aquarium and a sufficiently high resolution camera. Not only does his BubbleRNG make a rather relaxing sound while in operation, but according to tools such as ENT, NIST-STS, and DieHard, appears to be a source of true randomness.

If you want to build your own BubbleRNG, all you need is a tank of water and some air pumps to generate the bubbles. A webcam looking down on the surface of the water captures the chaos that ensues when the columns of bubbles generated by each pump collide. In the video after the break [Jason] uses two pumps, but considering they’re cheaper than lava lamps, we’d probably chuck a few more into the mix. To be on the safe side, he mentions that the placement and number of pumps should be arbitrary and not repeated on subsequent installations.

To turn this tiny maelstrom into a source of random numbers, OpenCV is first used to identify the bubbles in the video stream that are between a user-supplied minimum and maximum radius. The software then captures the X and Y coordinates of each bubble, and the resulting values are shuffled around and XOR’d until a stream of random numbers comes out the other end. What you do with this cheap source of infinite improbability is, of course, up to you.

While this project has been floating around (no pun intended) the Internet for a few years now, it seems to have gone largely overlooked, and was only just brought to our attention thanks to a tip from one of our illustrious readers. An excellent reminder that if you see something interesting out there, we’d love to hear about it.

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Bring The Smithsonian Home With 3D Printing

If you’ve ever been to Washington DC, you know the Smithsonian isn’t just a building, instead it’s a collection of 19 museums, 21 libraries, 9 research centers, and a zoo. Even though there are hundreds of affiliated museums, there is a way to bring at least some of the museum to you. The Smithsonian has a 3D digitization portal that currently features 124 models of items from the collection. Almost 100 of them have models you can download and print — or have someone print for you.

Printing yourself is probably the most cost-effective option if you already have a printer. According to the Smithsonian, if you want a 1/20th scale model of a T. Rex cranium, Shapeways will do it for about $21. If you want a 9-inch version of Neil Armstrong’s spacesuit, that would go for $130 or so.

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Restoring A 1949 Golden Throat Radio

[Mr. Carlson] has a really beautiful old 1949-era radio to restore and you can watch him do it in a comprehensive video, below. We aren’t sure what we were more amused by: the odd speaker that looks like a ceiling air vent or the sticker on the back certifying that the radio produces the tone of the “golden throat” signed by RCA’s chief engineer.

Electrically, the radio didn’t look that remarkable. Of course, the capacitors were presumed bad and replaced. The video made us remember how much we hated restringing dial radios!

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Drive A Plasma Ball With An ATV Ignition Coil And A 555

[Discrete Electronics Guy] sends in his short tutorial on building a high voltage power supply from simple things.

The circuit is a classic, but we love the resourcefulness shown. The ignition coil comes from a three wheeler, the primary power supply is a ATX supply from a computer and the oscillator is powered by a 9V battery. We do wonder whose vehicle stopped working though.

He gives a great explanation of how the circuit works and was constructed and then moves on to build his own Plasma bulb. Despite expecting something more complicated the end result was achieved by putting a lightbulb on a stick. Fantastic. The circuitry was nearly packaged into a takeaway food container and the entire construction was called complete.

All in all it shows what someone can accomplish if they’re resourceful and understand the basics. However, it’s probably that you don’t electroBoom yourself to death if you can avoid it.

Hackaday Superconference: An Analog Engineer Dives Into RF

Those of us who work with electronics will usually come to the art through a particular avenue that we master while imbibing what we need from those around it. For example, an interest in audio circuitry may branch into DSP and microcontrollers as projects become more complex. Some realms though retain an aura of impossibility, a reputation as a Dark Art, and chief among them for many people is radio frequency (RF). Radio circuitry is often surprisingly simple, yet that simplicity conceals a wealth of complexity because the medium does not behave in the orderly manner of a relatively static analogue voltage or a set of low-frequency logic levels.

Chris Gammell is a familiar face to many Hackaday readers for his mastery of much electronic trickery, so it comes as something of a surprise to find that RF has been one of the gaps in his knowledge. In his talk at the Hackaday Superconference he took us through his journey into RF work, and the result is a must-watch for anyone with a curiosity about radio circuitry who didn’t know where to start.

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Can You Piezo A Peugeot?

Car manufacturers have a problem when it comes to climate change. Among the variety of sources for extra atmospheric CO2 their products are perhaps those most in the public eye, and consequently their marketing departments are resorting to ever more desperate measures to sanctify them with a green aura. Among these are the French marque Peugeot, whose new electric version of their 208 model features in a slick video alongside a futuristic energy-harvesting billboard.

This is no ordinary billboard, nor is it a conventional wind turbine or solar array, instead it harvests ambient noise in one of the busiest parts of Paris, and turns it into electricity to charge the car with an array of piezoelectric energy capture units. This caught our eye here at Hackaday, because it seemed rather too good to be true. Is it a marketing stunt, or could you make a piezo billboard as a practical green energy device? Let’s take a closer look.

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Open-Source Satellite Propulsion Hack Chat

Join us on Wednesday, December 11 at noon Pacific for the Open-Source Satellite Propulsion Hack Chat with Michael Bretti!

When you look back on the development history of any technology, it’s clear that the successful products eventually reach an inflection point, the boundary between when it was a niche product and when it seems everyone has one. Take 3D-printers, for instance; for years you needed to build one if you wanted one, but now you can buy them in the grocery store.

It seems like we might be getting closer to the day when satellites reach a similar inflection point. What was once the province of nations with deep pockets and military muscles to flex has become far more approachable to those of more modest means. While launching satellites is still prohibitive and will probably remain so for years to come,  building them has come way, way down the curve lately, such that amateur radio operators have constellations of satellites at their disposal, small companies are looking seriously at what satellites can offer, and even STEM programs are starting to get students involved in satellite engineering.

Michael Bretti is on the leading edge of the trend toward making satellites more DIY friendly. He formed Applied Ion Systems to address one of the main problems nano-satellites face: propulsion. He is currently working on a range of open-source plasma thrusters for PocketQube satellites, a format that’s an eighth the size of the popular CubeSat format. His solid-fuel electric thrusters are intended to help these diminutive satellites keep station and stay in orbit longer than their propulsion-less cousins. And if all goes well, someday you’ll be able to buy them off-the-shelf.

Join us for the Hack Chat as Michael discusses the design of plasma thrusters, the details of his latest testing, and the challenges of creating something that needs to work in space.

join-hack-chatOur Hack Chats are live community events in the Hack Chat group messaging. This week we’ll be sitting down on Wednesday, December 11 at 12:00 PM Pacific time. If time zones have got you down, we have a handy time zone converter.

Click that speech bubble to the right, and you’ll be taken directly to the Hack Chat group on You don’t have to wait until Wednesday; join whenever you want and you can see what the community is talking about.