The “P Cell” Is Exactly What You Might Suspect

August 6, 2018 by 34 Comments

[Josh Starnes] had a dream. A dream of a device that could easily and naturally be activated to generate power in an emergency, or just for the heck of it. That device takes in urea, which is present in urine, and uses it to generate a useful electrical charge. [Josh] has, of course, named this device the P Cell.

An early proof of concept uses urine to create a basic galvanic cell with zinc and copper electrodes, but [Josh] has other ideas for creating a useful amount of electricity with such a readily-available substance. For example, the urea could be used to feed bacteria or micro algae in a more elegantly organized system. Right now the P Cell isn’t much more than a basic design, but the possibilities are more than just high-minded concepts. After all, [Josh] has already prototyped a Hybrid Microbial Fuel Cell which uses a harmonious arrangement of bacteria and phytoplankton to generate power.

[Josh]’s entries were certainly among some of the more intriguing ones we saw in the Power Harvesting Challenge portion of The Hackaday Prize, and we’re delighted that his ideas will be in the running for the Grand Prize of $50,000.

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DSO Nano 3 Review: A 20 MHz Pocket ‘Scope For Not A Lot

August 6, 2018 by 45 Comments

The oscilloscope is an essential tool of any electronics bench, and it is also an instrument whose capabilities have expanded exponentially over the decades. Your entirely analogue CRT ‘scope of a few decades ago has now been supplanted by a digital device that takes on many of the functions of both an expensive multimeter a frequency counter, and more. At the top end of the market the sky is the limit when it comes to budget, and the lower end stretches down to low-bandwidth devices based upon commodity microcontrollers for near-pocket-money prices.

These super-cheap ‘scopes are usually sold as kits, and despite their very low bandwidth are surprisingly capable instruments with a useful feature set due to well-written software. I  reviewed a typical model last year, and came away lamenting its lack of an internal battery and a decent quality probe. If only someone would produce an inexpensive miniature ‘scope with a decent bandwidth, decent probe, and an internal battery!

As it happens, I didn’t have long to wait for my wish to be satisfied, with news of the release of the DSO Nano 3. Let’s see what you can do with a portable scope for less than $50.

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Learn FPGA Fast With Hackaday’s FPGA Boot Camp

August 6, 2018 by 39 Comments

FPGAs have gone from being a niche product for people with big budgets to something that every electronics experimenter ought to have in their toolbox. I am always surprised at how many people I meet who tell me they are interested in using FPGAs but they haven’t started. If you’ve been looking for an easy way to get started with FPGAs, Hackaday’s FPGA boot camp is for you. There’s even a Hackaday.io chat in the group specifically for FPGA talk for questions and general discussion!

While it is true FPGAs aren’t for everything, when you need them you really need them. Using FPGAs you can build logic circuits — not software simulations, but real circuits — and reap major performance benefits compared to a CPU. For digital signal processing, neural networks, or computer vision applications, being able to do everything essentially in parallel is a great benefit. Sometimes you just need the raw speed of a few logic gates compared to a CPU plodding methodically through code. We expect to see a lot more FPGA activity now that Arduino is in the game.

These boot camps gather together some of the material you seen spread over many articles here before, plus new material to flesh it out. It’s designed for you to work through more like a training class than just some text to read. There’s plenty of screenshots and even animations to help you see what you are supposed to be doing. You’ll be able to work with simulations to see how the circuits we talk about work, make changes, and see the results. We’ll focus on Verilog — at least for now — as it is close to C and easier for people who know C to pick up. Still not convinced? Let’s run though the gist of the boot camp series.

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Feeling The Heat Of High-Frequency Trading

August 6, 2018 by 45 Comments

It’s high summer here in North America, and for a lot of us, this one has been a scorcher. Media reports have been filled with coverage of heat wave after heat wave, with temperature records falling like dominoes.

But as they say, it’s not the heat, it’s the humidity, and that was painfully true in the first week of July as a slug of tropical air settled into the northeast United States. With dewpoints well into the 70s (25°C plus) and air temperatures pushing the century-mark (38°C), people suffered and systems from transportation to the electrical grid strained under the load. But as punishing as such soupy conditions are for people, there are other effects that are less well known but of critical importance to financial markets, where increased humidity can lead to billion-dollar losses for markets. Welcome to the weird world of high-frequency trading.

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Mouse Trap Game Used As An Actual Mouse Trap

August 6, 2018 by 7 Comments

Just when you thought you had explored all the weird stuff on YouTube, along comes [Shawn Woods] with his channel dedicated to testing different types of mouse traps. His weekly videos demonstrate the construction and ultimate effectiveness of everything from primitive traps that can be made in the field from sticks and rocks to 3D printed creations sent in from viewers. But his latest video might just be the weirdest one yet, as he found a way to use the classic “Mousetrap” board game to capture an actual rodent.

Well, sort of. For one, [Shawn] admits the “trap” is completely impractical and is just for fun. Which should be pretty obvious considering the thing is enclosed in a box the size of a small refrigerator. Second, the lucky rodent that gets to test drive this Milton Bradley-powered gadget is actually the family’s pet chinchilla which is obviously rather calm and we dare say accustomed to these sort of shenanigans.

The key to the whole contraption comes via two traditional mousetraps, one on either end of the game’s more fanciful rendition of the same device. The first trap is used to pull the crank which gets the board game going when the mouse steps on the pad (a piece of wood with padding prevents the bar from actually hitting the animal). The game goes through its nostalgic routine featuring metal balls rolling down tracks and figurines on jumping boards, eventually triggering the second real mouse trap. In this case, the trap pulls a rope which closes a door at the opening of the box.

Assuming your target rodent is very patient and not startled by the cacophony of plastic machinery, the whole thing works perfectly. To use the parlance of his channel, this is what’s known as a “Live Catch” trap as it doesn’t hurt the mouse and lets you easily remove them after the fact. Which is the least you could do after humiliating it like this.

While likely the most unique, it surely isn’t the only mouse trap we’ve ever covered here at Hackaday. This clever soda bottle trap can be built cheaply and easily, but if you want something expensive and complex you can always use a Raspberry Pi.

[Thanks to Pete for the tip.]

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Rolling Out A Slick Rotary Phase Converter

August 6, 2018 by 46 Comments

Home machinists can often find great deals on used industrial equipment, and many a South Bend lathe or Bridgeport milling machine has followed someone home. Then comes the moment to plug it in, and the new owner discovers that the three-phase plug needed to power the new beast is nowhere to be found in the shop. Thus commences the weeping and the gnashing of teeth.

Luckily, [Handmade Extreme] is ahead of the curve in terms of shop power, and built a rotary phase converter to power his machines. Industry generally runs on three-phase AC systems, mainly because three-phase electric motors are so much more efficient and compact than the equivalent single-phase motor. But residential electrical service is either split-phase or, in the UK where [Handmade Extreme] is based, single phase. A rotary phase converter is an electromechanical device that can generate the missing phases – in essence a three-phase motor that can run on one winding and generate the missing phases across the other windings. It needs some supporting control circuitry to do so, such as timers and contactors to switch the winding connections once the motor starts, plus capacitors for motor starting and for balancing the voltage across the phases. The control gear is DIN-rail mounted and neatly wired to a smart-looking control panel. Everything is housed in a sturdy enclosure that’s big enough to serve as a mobile tool cart. It’s a really nice job – watch the whole build in the video below.

If you’re interested in power distribution, we’ve got a primer that covers the basics. And if you’re in the market for machine tools, [Quinn]’s machine tool buyer’s guide will let you decide if a three-phase machine is worth the extra effort.

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Spot Welding …Plastic?

August 5, 2018 by 12 Comments

Plastic milk bottles, when your project or prototype needs an urgent source of plastic, they are often the first thing to hand. Convenient and flexible, but strong at the same time and usually free, they’re the ultimate source of material in a pinch. However, when it comes to actually manipulating the HDPE plastic they’re made from, there’s often a challenge. It’s easy to cut, but not so easy to join. Conventional glues can have a hard time, making it difficult to bond.

Enter [zimitt], and a spot welding solution for joining HDPE with ease. Ok, so ‘spot welding’ might be a little optimistic given the speed of this process, but it’s useful nonetheless. To heat the plastic, a cheap soldering iron is recommended. A low wattage, straight-to-the-wall one does well, especially as they commonly have the washer-style end shown in the picture. To protect the plastic from burning, a BBQ mat is used – they’re temperature resistant and usually made with a PTFE surface.

First, place the two sheets of plastic face to face and sandwich top and bottom with the BBQ mat. Apply some heat to the mat with the soldering iron then, after a few seconds, remove the iron and provide pressure with a flat object to bond the plastic. [zimitt] used an espresso tamper for this which was ideal.

The results are impressive, and [zimitt] experiments with different plastics as well. Of course, you should exercise caution when attempting anything like this, given the health risks present when heating up different types of plastic.

HDPE is easy to recycle at home, and we’ve seen a lot of great uses: a plastic joiner’s mallet, plastic tiles, and even a filament extruder for 3D printing.