Make Water Bridges With High Voltages

November 15, 2016 by Richard Baguley 42 Comments

It’s generally a bad idea to mix high voltage electricity and water, but interesting things happen if you do. This video from [RWGResearch] shows one of them: water bridging. If you have two water sources (such as two beakers full of very highly distilled water) with a high voltage between them, the voltage can create a gravity defying bridge that flows between them.

The experiment starts with the pouring spouts from two beakers nearly touching each other. Water fills the beakers right up to the spout, but it’s the application of electricity that pulls the bridge between the positive and negative beakers. With care, this technique can create a bridge of up to 2cm (about 0.8 inches). [RWGResearch] shows that he is able to create a bridge of about a centimeter with a 5KV voltage, but which only carries a few milliamps.

What forces are at play here isn’t exactly clear, but one recent paper speculates that it’s down to a combination of the dielectric force caused by the differing charges of parts of water molecules and the surface tension of the water. Whatever it is, it is fascinating and makes for a neat trick.

Want to make your own contribution to the scientific body of knowledge? Prove or disprove the speculation mentioned in the Wikipeadia article: is this possible because of an H3O2 lattice formed by the high voltage? How would you formulate a test for this?

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Archaeology, Virtually.

November 14, 2016 by James Hobson 3 Comments

Drone technology is seeing useful application in a new field seemingly every day — so it was only a matter of time before it saw use in archaeology. And so, a team of researches in Australia are combining drone and VR modeling technology to help investigate the Plain of Jars, in Laos.

After the drone images the site, those photos are patched together by object recognition software and are reviewed in the immersive CAVE2 3D facility at Melbourne, Australia’s Monash University. Multiple surveys catalog and archive the dig at various stages and enable the archaeologists to continue investigating the site after leaving — especially useful for digs in dangerous regions. In this case, the landscape around the Plain of Jars is dotted with unexploded cluster bomblets.

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Documentation? Wave Me!

November 14, 2016 by Al Williams 15 Comments

A lot of hardware and software hackers aren’t all that keen on documentation. The problem is, if you don’t document, it is harder for people to replicate or build on your work. If you aren’t happy writing, keep the old adage in mind: a picture is worth a thousand words.

With a digital design, a timing diagram is often a key piece of documentation. WaveMe is a free Windows program that makes it easy to create good-looking timing diagrams. You can run the software on other platforms via Wine.

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Getting A Handle On ESR With A Couple Of DIY Meters

November 14, 2016 by Dan Maloney 11 Comments

Got a bunch of questionable electrolytic caps sitting in your junk bin? Looking to recap a vintage radio chassis? Then you might need to measure the equivalent series resistance of the capacitors, in which case this simple five-transistor ESR meter might come in handy.

Even if you have no need for an ESR meter, [W2AEW]’s video below is a solid introduction to how ESR is determined. The circuit itself comes from EEVBlog forum user [Jay-Diddy_B] and is about as simple as such a circuit can get. Two transistors form an oscillator that generates a square wave that drives a resistor bridge network. The two legs of the bridge feed matched common-emitter amps, one leg through the device under test. The difference in voltage between the two legs is read on a meter, and you have a quick and simple way to sort through the caps in your junk bin. [Jay-Diddy_B]’s circuit is only presented in breadboard form; no attempt was made to field a practical instrument. Indeed, [W2AEW] already built a home-brew ESR meter using hex inverters and op amps to which he compares the five-transistor circuit’s results. His intention here seems to be to clarify the technique of ESR measurement and evaluate an even simpler circuit than his. We think he’s done a good job on both counts.

We’ve featured plenty of [WA2AEW]’s work before, like this Michigan Mity-Mite transmitter or his primer on oscilloscopes. We really like his laid back style and the way he makes complex topics easy to understand. Check them out.

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Power Wheels Rescued, Restored And Enhanced

November 14, 2016 by Steven Dufresne 14 Comments

It seems power wheels are like LEGO — they’re handed down from generation to generation. [Nicolas] received his brand-new Peg-Perego Montana power wheels in 1997 as a Christmas present. After sitting in a barn for a decade, and even being involved in a flood, it was time to give it to his godchildren, though not without some restoration and added features. His webpages have a very good write-up, just shy of including schematics, but you’ll find an abbreviated version below.

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New Part Day: Smoothie For RAMPS

November 14, 2016 by Brian Benchoff 59 Comments

When it comes to 3D printer controllers, there are two main schools of thought. The first group is RAMPS or RAMBo which are respectively a 3D printer controller ‘shield’ for the Arduino Mega and a stand-alone controller board. These boards have been the standard for DIY 3D printers for a very long time, and are the brains for quite a few printers from the biggest manufacturers. The other school of thought trundles down the path of ARM, with the most popular boards running the Smoothie firmware. There are advantages to running a printer with an ARM microcontroller, and the SmoothieBoard is fantastic.

Re-ARM for RAMPS — a Kickstarter that went live this week — is the middle ground between these two schools of thought. It’s a motherboard for RAMPS, but brings the power of a 32-bit LPC1768 ARM processor for all that smooth acceleration, fine control, and expansion abilities the SmoothieBoard brings.

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RC receiver to arduino converter for BB-8

Ask Hackaday: How Do You Convert Negative Voltages To Positive?

November 14, 2016 by Steven Dufresne 81 Comments

I have a good background working with high voltage, which for me means over 10,000 volts, but I have many gaps when it comes to the lower voltage realm in which RC control boards and H-bridges live. When working on my first real robot, a BB-8 droid, I stumbled when designing a board to convert varying polarities from an RC receiver board into positive voltages only for an Arduino.

Today’s question is, how do you convert a negative voltage into a positive one?

In the end I came up with something that works, but I’m sure there’s a more elegant solution, and perhaps an obvious one to those more skilled in this low voltage realm. What follows is my journey to come up with this board. What I have works, but it still nibbles at my brain and I’d love to see the Hackaday community’s skill and experience applied to this simple yet perplexing design challenge.

The Problem

I have an RC receiver that I’ve taken from a toy truck. When it was in the truck, it controlled two DC motors: one for driving backwards and forwards, and the other for steering left and right. That means the motors are told to rotate either clockwise or counterclockwise as needed. To make a DC motor rotate in one direction you connect the two wires one way, and to make it rotate in the other direction you reverse the two wires, or you reverse the polarity. None of the output wires are common inside the RC receiver, something I discovered the hard way as you’ll see below.

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