Looking Mains Voltage In The Eye And Surviving

It is often a surprise to see how other people react to mains electricity when they encounter it in a piece of equipment. As engineers who have dealt with it both personally and professionally for many years it is easy to forget that not everyone has had that experience. On one hand we wince at those who dive in with no fear of the consequences, on the other we are constantly surprised at the number of people who treat any item with more than a few volts in it as though it was contaminated with radioactive anthrax and are scared to even think about opening it up.

We recently had a chat among the Hackaday writers about how we could approach this subject. The easy way out is to be all Elf-and-Safety and join the radioactive anthrax crowd. But the conclusion we came to was that this site is a resource for hackers and makers. Some of you are going to lift the lid on boxes containing significant voltages no matter what, so we thought we’d help you do it safely rather than just listen for the distant screams.

So here follows the first in a series on how to approach electronic devices containing high voltages, and live to tell the tale. By “high voltages” we mean anything up to mains voltages, and those directly derived from them such as the few hundred volts rectified DC you’ll find in a switch-mode PSU. For multi-kilovolt EHT you’ll have to wait for another article, because that is an entire subject in itself. We’ll mention these higher voltages in passing, but their detail is best left for a Hackaday colleague with more pertinent experience.

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Don’t Ignore The Artist’s Supply Store

So it’s Saturday morning and you’ve found yourself with an urge to build something involving copper plates or carbon electrodes. Maybe you need a metallic powder for a chemistry experiment. Casting supplies? Pure lead? Copper mesh? Silver wire?  Odd tools? Exceedingly caustic etchants?  There’s a store that sells it all, and it’s not usually frequented by hackers: the art store.

If you know where to look, the store is full of useful things. Each method of expression in art has its own set of supplies; a bountiful collection of various processes and the useful things therein. I grew up in a city that did not have a real art supply store. It had one of those big box craft stores that assault you with glittery plasticized flowers and terrible manufactured scents. When I moved to a different city and walked over to the local art supply to purchase some new pens I ended up staying for a few hours just looking at all the cool things they had for sale.

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The Coming Wide-Spread Use Of Drones In Agriculture

Whether you call them UAVs (Unmanned Aerial Vehicles), UAS (Unmanned Aerial System), Drones, or something less polite – people are more familiar than ever with them. We’ll call them drones, and we’re not talking about the remote-controlled toy kind – we’re talking about the flying robot kind. They have sensors (GPS and more), can be given a Flight Plan (instructions on where to go), and can follow that plan autonomously while carrying out other instructions – no human pilot required. Many high-end tractors are already in service with this kind of automation and we’ve even seen automated harvesting assistance. But flying drones are small and they don’t plant seeds or pull weeds, so what exactly do they have to do with agriculture?

There are certain things that drones are very good at, and there are things in agriculture that are important but troublesome to do or get. Some of these things overlap, and in those spaces is where a budding industry has arisen.

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Up Your CAD Game With Good Reference Photos

I’ve taken lots of reference photos for various projects. The first time, I remember suffering a lot and having to redo a model a few times before I got a picture that worked. Just like measuring parts badly, refining your reference photo skills will save you a lot of time and effort when trying to reproduce objects in CAD. Once you have a model of an object, it’s easy to design mating parts, to reproduce the original, or even for milling the original for precise alterations.

I’m adding some parts onto a cheap food dehydrator from the local import store. I’m not certain if my project will succeed, but it’s a good project to talk about taking reference photos. The object is white, indistinct, and awkward, which makes it a difficult object to take a good photo for reference use in a CAD program. I looked around for a decent tutorial on the subject, and only found one. Maybe my Google-fu wasn’t the best that day. Either way, It was mostly for taking good orthogonal shots, and not how to optimize the picture to get dimensions out of it later.

There are a few things to note when taking a reference photo. The first is the distortion and the setup of your equipment to combat it. The second is including reference scales and surfaces to assist in producing a final model from which geometry and dimensions can be accurately taken. The last is post-processing the picture to try to fight the distortion, and also to prepare it for use in cad and modeling software.

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Which Wireless Tech Is Right For You?

It seems these days all the electronics projects are wireless in some form. Whether you choose WiFi, Bluetooth Classic, Bluetooth Low Energy, ZigBee, Z-Wave, Thread, NFC, RFID, Cell, IR, or even semaphore or carrier pigeon depends a lot on the constraints of your project. There are a lot of variables to consider, so here is a guide to help you navigate the choices and come to a conclusion about which to use in your project.

We can really quickly reduce options down to the appropriate tech with just a few questions.

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Analog To Digital Converter (ADC): A True Understanding

Back in the day where the microprocessor was our standard building block, we tended to concentrate on computation and processing of data and not so much on I/O. Simply put there were a lot of things we had to get working just so we could then read the state of an I/O port or a counter.

Nowadays the microcontroller has taken care of most of the system level needs with the luxury of built in RAM memory and the ability to upload our code. That leaves us able to concentrate on the major role of a microcontroller: to interpret something about the environment, make decisions, and often output the result to energize a motor, LED, or some other twiddly bits.

Often the usefulness of a small microcontroller project depends on being able to interpret external signals in the form of voltage or less often, current. For example the output of a photocell, or a temperature sensor may use an analog voltage to indicate brightness or the temperature. Enter the Analog to Digital Converter (ADC) with the ability to convert an external signal to a processor readable value.

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Volkswagen Beetle – The Most Hackable Car

If you build a better mousetrap, the world will beat a path to your door. Of course it helps if your mousetrap is reliable, simple, cheap, and easy to work on. In the car world, look no further than arguably the most successful, and most hackable, car in history: the Volkswagen Type 1, more commonly known as the Beetle. The ways in which this car was modified to suit the needs of a wide range of people over its 65-year-long production run proves that great design, ease of use, and simplicity are the keys to success, regardless of the project or product.

Built by Ferdinand Porsche in 1930’s Germany, the Beetle was designed to be a car for anyone and everyone. Its leader at the time wanted a true “people’s car” (i.e. “Volkswagen”) that was affordable for a German family, could reliably travel at sustained highway speeds on the new German autobahns, and easily be repaired by its owners. The car features an air-cooled engine for simplicity and cost savings: no radiator, water pump, or coolant, plus reduced overall complexity. The engine can be easily removed by disconnecting the fuel line, the throttle cable, and the four bolts that hold it to the transaxle. The entire body is held on to the chassis by eighteen bolts and is also easy to remove by today’s standards. There’s no air conditioning, no power steering, and a rudimentary heater of sorts for the passenger cabin that blows more hot air depending on how fast the engine is running. But possibly the best example of its simplicity is the fact that the windshield washer mechanism is pressurised with air from the over-inflated spare tire, eliminating the need to install another piece of equipment in the car.

It’s not too big of a leap to realize how easily hackable this car is. Even Volkswagen realized this and used the platform to build a number of other vehicles: the Type 2 (otherwise known as the bus, van, hippie van, Kombi, etc.) the eclectic Karmann Ghia, and the Types 3 and 4. Parts of the Type 1 were used to build the Volkswagen 181, commonly referred to as “the Thing”. Ferdinand Porsche also used design elements and other parts of the Type 1 to build the first Porsche, essentially making a souped-up Beetle. The rear-engine, rear-wheel drive layout of modern Porsches is a relic of this distant Beetle cousin. But the real magic is what people started doing to the Beetles in their backyards in the ’60s and 70s: turning them into buggies, off road machines, race cars, and hot rods that are still used today.

At some point around this time, a few people realized that the Beetle was uniquely suited to off-road racing. The type of suspension combined with the rear-engine, rear-wheel-drive layout meant that even without four-wheel drive, this car could excel in desert racing. There are still classes in this race for stock Beetles and modified Beetles called Baja Bugs.

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