Two Guys, A Hotel Room And A Radio Fire

May 13, 2016 by Gregory L. Charvat 45 Comments

Can you build a HF SSB radio transciever in one weekend, while on the road, at parts from a swap meet? I can, but apparently not without setting something on fire.

Of course the swap meet I’m referring to is Hamvention, and Hamvention 2016 is coming up fast. In a previous trip to Hamvention, Scott Pastor (KC8KBK) and I challenged ourselves to restore tube radio gear in a dodgy Dayton-area hotel room where we repaired a WW2 era BC-224 and a Halicrafters receiver, scrounging parts from the Hamfest.

Our 2014 adventures were so much fun that it drove us to create our own hacking challenge in 2015 to cobble together a <$100 HF SSB transceiver (made in the USA for extra budget pressure), an ad-hoc antenna system, put this on the air, and make an out-of-state contact before the end of Hamvention using only parts and gear found at Hamvention. There’s no time to study manuals, antennas, EM theory, or vacuum tube circuitry. All you have are your whits, some basic tools, and all the Waffle House you can eat. But you have one thing on your side, the world’s largest collection of surplus electronics and radio junk in one place at one time. Can it be done?

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To See Within: Making Medical X-rays

May 12, 2016 by Dan Maloney 47 Comments

I was a bit of a lost soul after high school. I dabbled with electrical engineering for a semester but decided that it wasn’t for me – what I wouldn’t give for a do-over on that one. In my search for a way to make money, I stumbled upon radiologic technology – learning how to take X-rays. I figured it was a good way to combine my interests in medicine, electronics, and photography, so after a two-year course of study I got my Associates Degree, passed my boards, and earned the right to put “R.T.(R) (ARRT)” after my name.

That was about as far as that career went. There are certain realities of being in the health care business, and chief among them is that you really have to like dealing with the patients. I found that I liked the technology much more than the people, so I quickly moved on to bigger and better things. But the love of the technology never went away, so I thought I’d take a look at exactly what it takes to produce medical X-rays, and see how it’s changed from my time in the Radiology Department.

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Path To Craftsmanship: Safety, Cleanliness, And Documentation As Habits

May 12, 2016 by Gerrit Coetzee 49 Comments

When I started boxing classes I was told, at my level, I could do just as much good for my form by doing core exercises such as crunches, running, push-ups, and pull-ups for a month as I could by doing the class. I consder habits like safety, cleanliness, and documentation to be habits that influence the quality of hacks much the same way. They’re not really related, and the work can get done without them, but their implementation alone improves the quality of everything you do at the workbench.

The best mechanic I’ve ever met had a well-organized shop. All of his employees wore nitrile gloves when they worked on engines to protect their hands from the chemicals inside. They used ear protection and safety glasses. His rates were low, and the car was always repaired fast. I never had to go back for the same repair twice. He knew exactly what repairs were done, and even kept the parts removed from my vehicle to show me if I desired. I got some of the most fantastic explanations of why parts failed from him. Two blocks down the street was a shop which was unorganized and had double rates. The employees were always sitting on the waiting chairs in the lounge. It took one trip there to never return.

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Open Robots With Open Roberta

May 11, 2016 by Elliot Williams 11 Comments

Kids, and Hackaday editors, love robots! The Open Roberta project (OR) takes advantage of this to teach kids about programming. And while the main focus is building a robot programming language that works for teaching grade-school and high-school kids, it’s also a part of a large open source robotics ecosystem that brings a lot more to the table than you might think. We talked with some folks at Google, one of the projects’ sponsors, about where the project is and where it’s going.

Building a robot can be very simple — assembling pre-configured parts or building something small, quick, and cute — or it can be an endeavour that takes years of sweat and tears. Either way, the skills involved in building the ‘bot aren’t necessarily the same as those it takes to program the firmware that drives it, and then eventually the higher-level software that makes it functional and easy to drive.

OR, as an educational project, makes it very, very easy for kids to start off programming robots, but it’s expandable as the user gets more experienced. And since everything is open source, it’s part of a whole ecosystem that makes it even more valuable. We think it’s worth a look (along with something significantly more complex like ROS) if you’re playing around with robotics.

System Architecture

Open Roberta is the user-facing middleware in a chain of software and firmware bits that make a robot work in a classroom environment. For the students, everything runs inside a browser. OR provides a webserver, robot programming interface and language, and then converts the output of the students’ programs to something that can be used with the robots’ firmware. The robots that are used in classrooms are mostly based on the Lego Mindstorms EV3 platform because it’s easy to put something together in short order. (But if you don’t have an EV3, don’t despair and read on!)

The emphasis is on ease of entry for the students and the teachers supervising the class. Everything runs in a browser, so there’s nothing to install on the client side. The students connect to a server that directs the robots, communicating with the robots’ own operating system, and uploading the students’ programs.

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Looking Mains Voltage In The Eye And Surviving

May 11, 2016 by Jenny List 198 Comments

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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Tools Of The Trade – Component Placing

May 10, 2016 by Bob Baddeley 34 Comments

Recently we started a series on the components used to assemble a circuit board. The first issue was on dispensing solder paste. Moving down the assembly line, with the paste already on the board, the next step is getting the components onto the PCB. We’re just going to address SMT components in this issue, because the through hole assembly doesn’t take place until after the SMT components have gone through the process to affix them to the board.

SMT components will come in reels. These reels are paper or plastic with a clear plastic strip on top, and a reel typically has a few thousand components on it. Economies of scale really kick in with reels, especially passives. If you order SMT resistors in quantities of 1-10, they’re usually $.10 each. If you order a reel of 5000, it’s usually about $5 for the reel. It is cheaper to purchase a reel of 10 kOhm 0603 resistors and never have to order them again in your life than it is to order a few at a time. Plus the reel can be used on many pick-and-place machines, but the cut tape is often too short to use in automated processes.

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Don’t Ignore The Artist’s Supply Store

May 10, 2016 by Gerrit Coetzee 49 Comments

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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