Working with high voltage is like working with high pressure plumbing. You can spring a leak in your plumbing, and of course you fix it. And now that you’ve fixed that leak, you’re able to increase the pressure still more, and sometimes another leak occurs. I’ve had these same experiences but with high voltage wiring. At a high enough voltage, around 30kV or higher, the leak manifests itself as a hissing sound and a corona that appears as a bluish glow of excited ions spraying from the leak. Try to dial up the voltage and the hiss turns into a shriek.
Why do leaks occur in high voltage? I’ve found that the best way to visualize the reason is by visualizing electric fields. Electric fields exist between positive and negative charges and can be pictured as electric field lines (illustrated below on the left.) The denser the electric field lines, the stronger the electric field.
Weak and strong electric fields
Ionization in electric fields
The stronger electric fields are where ionization of the air occurs. As illustrated in the “collision” example on the right above, ionization can happen by a negatively charged electron leaving the electrically conductive surface, which can be a wire or a part of the device, and colliding with a nearby neutral atom turning it into an ion. The collision can result in the electron attaching to the atom, turning the atom into a negatively charged ion, or the collision can knock another electron from the atom, turning the atom into a positively charged ion. In the “stripping off” example illustrated above, the strong electric field can affect things more directly by stripping an electron from the neutral atom, again turning it into a positive ion. And there are other effects as well such as electron avalanches and the photoelectric effect.
In either case, we wanted to keep those electrons in the electrically conductive wires or other surfaces and their loss constitutes a leak in a very real way.
Continue reading “Wrangling High Voltage”
Most of the incredible flight simulator enthusiasts with 737 cockpits in their garage are from the US. What happens when they’re from Slovenia? They built an A320 cockpit. The majority of the build comes from an old Cyprus Airways aircraft, with most of the work being wiring up the switches, lights, and figuring out how to display the simulated world out of the cockpit.
Google Cardboard is the $4 answer to the Oculus Rift – a cardboard box and smartphone you strap to your head. [Frooxius] missed being able to interact with objects in these 3D virtual worlds, so he came up with this thing. He adapted a symbol tracking library for AR, and is now able to hold an object in his hands while looking at a virtual object in 3D.
Heat your house with candles! Yes, it’s the latest Indiegogo campaign that can be debunked with 7th grade math. This “igloo for candles” will heat a room up by 2 or 3 degrees, or a little bit less than a person with an average metabolism will.
Last week, we saw a post that gave the Samsung NX300 the ability to lock the pictures taken by the camera with public key cryptography. [g3gg0] wrote in to tell us he did the same thing with a Canon EOS camera.
The guys at Flite Test put up a video that should be handy for RC enthusiasts and BattleBot contenders alike. They’re tricking out transmitters, putting push buttons where toggle switches should go, on/off switches where pots should go, and generally making a transmitter more useful. It’s also a useful repair guide.
[Frank Zhao] made a mineral oil aquarium and put a computer in it. i7, GTX 970, 16GB RAM, and a 480GB SSD. It’s a little bigger than most of the other aquarium computers we’ve seen thanks to the microATX mobo, and of course there are NeoPixels and a bubbly treasure chest.
For the last decade or so, [Jason] has wanted to build an underwater robot. Can you blame him? More recently, he’s been researching sonar sensing and experimenting with the relatively inexpensive HC-SR04 module. Since he had good luck getting it to work with a PC sound card and a Stellaris Launchpad, he figured it was time to try using it underwater.
Hydrophone research led him to the idea of submerging the sensor in mineral
water oil to both seal it and couple it with the water. Unfortunately, the HC-SR04 only sends one pulse and waits for echo. Through the air, it reliably and repeatedly returned a small value. Once inside a pill bottle filled with mineral oil, though, it does something pretty strange: it fluctuates between sending back a very small value and an enormous value. This behavior has him stumped, so he’s going to go back to the Launchpad unless you can help him figure out what’s going on. Should he use a different method to seal it?
Fail of the Week is a Hackaday column which runs every Thursday. Help keep the fun rolling by writing about your past failures and sending us a link to the story — or sending in links to fail write ups you find in your Internet travels.
After he saw a ‘falling water display,’ [Matt] figured he could turn that idea on its head. He built a display that uses bubbles for pixels. Even though the build isn’t complete, we love the results so far.
[Matt] began his build constructing a tall, thin water tank out of acrylic. Eight solenoids were mounted in the base of the tank, attached to an aquarium air supply, plastic tubing, and one way valves. The first run of the bubble display didn’t go too well, but after adding dividers between each column the display started working.
With the dividers, [Matt] no longer had to worry about bubbles colliding or moving any direction but up. The bubbles weren’t moving consistently, so he replaced the water with mineral oil. Oil made a huge improvement, but the bubbles still float up at different speeds. [Matt] ascribes this to the unregulated air supply, but we’re thinking this problem could be mitigated with glycerine like the previous bubble display we saw.
It may still have some problems, but we love the result. Check out the video of bubbles in mineral oil after the break.
Continue reading “Displaying bubbles in mineral oil”