The IP Of The Infinite Build Volume 3D Printer

June 6, 2017 by Brian Benchoff 55 Comments

Last week, the Blackbelt 3D printer launched on Kickstarter. What makes the Blackbelt 3D printer different than any other 3D printer on Kickstarter? This printer has an infinite build volume. It’s built for continuous production. As long as you have a large enough spool of filament, this printer will keep producing plastic parts with no downtime in between. The Blackbelt is a truly remarkable and innovative machine. Yes, it’s a bit expensive, but it’s designed for production and manufacturing, not some guy tinkering in his garage.

However, the Blackbelt 3D website includes two words that have sent the 3D printer community into an uproar. ‘Patent Pending’ is something no one in the community wants to see given the history of the industry and a few poor decisions from the first movers during the great 3D printer awakening of 2010. The idea of an infinite build volume printer that allows for continuous production is not new; we saw one last March at the Midwest RepRap Festival. The question, therefore, is what is covered by the upcoming Blackbelt patents, what is the prior art, and is it still possible to build an Open Source printer that uses these innovative techniques?

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FPGA Rescues Scope From The Dumpster

June 1, 2017 by Adil Malik 62 Comments

I’m always on the lookout for a quality addition to my lab that would respect my strict budget. Recently, I’ve found myself pushing the Hertz barrier with every other project I do and hence desperately wanted a high bandwidth scope. Unfortunately, only recently have 70 MHz to 100 MHz become really affordable, whilst a new quad channel oscilloscope in the 500 MHz to 1 GHz range still costs a fortune to acquire. My only option was to find an absolute miracle in the form of an old high bandwidth scope.

It seemed the Gods of Hand Me Down electronics were smiling upon me when I found this dumpster destined HP 54542C. It appeared to be in fairy good shape and was the Top Dog in its day. But something had to be broken right? Sure enough, the screen was clearly faulty and illegible. Want to know how I fixed it? Four letters: FPGA.

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Embed With Elliot: LIN Is For Hackers

May 26, 2017 by Elliot Williams 18 Comments

A car is a rolling pile of hundreds of microcontrollers these days — just ask any greybeard mechanic and he’ll start his “carburetor” rant. All of these systems and sub-systems need to talk to each other in an electrically hostile environment, and it’s not an exaggeration to say that miscommunication, or even delayed communication, can have serious consequences. In-car networking is serious business. Mass production of cars makes many of the relevant transceiver ICs cheap for the non-automotive hardware hacker. So why don’t we see more hacker projects that leverage this tremendous resource base?

The backbone of a car’s network is the Controller Area Network (CAN). Hackaday’s own [Eric Evenchick] is a car-hacker extraordinaire, and wrote up most everything you’d want to know about the CAN bus in a multipart series that you’ll definitely want to bookmark for reading later. The engine, brakes, doors, and all instrumentation data goes over (differential) CAN. It’s fast and high reliability. It’s also complicated and a bit expensive to implement.

In the late 1990, many manufacturers had their own proprietary bus protocols running alongside CAN for the non-critical parts of the automotive network: how a door-mounted console speaks to the door-lock driver and window motors, for instance. It isn’t worth cluttering up the main CAN bus with non-critical and local communications like that, so sub-networks were spun off the main CAN. These didn’t need the speed or reliability guarantees of the main network, and for cost reasons they had to be simple to implement. The smallest microcontroller should suffice to roll a window up and down, right?

In the early 2000s, the Local Interconnect Network (LIN) specification standardized one approach to these sub-networks, focusing on low cost of implementation, medium speed, reconfigurability, and predictable behavior for communication between one master microcontroller and a small number of slaves in a cluster. Cheap, simple, implementable on small microcontrollers, and just right for medium-scale projects? A hacker’s dream! Why are you not using LIN in your multiple-micro projects? Let’s dig in and you can see if any of this is useful for you. Continue reading “Embed With Elliot: LIN Is For Hackers” →

Ohm? Don’t Forget Kirchhoff!

May 25, 2017 by Al Williams 52 Comments

It is hard to get very far into electronics without knowing Ohm’s law. Named after [Georg Ohm] it describes current and voltage relationships in linear circuits. However, there are two laws that are even more basic that don’t get nearly the respect that Ohm’s law gets. Those are Kirchhoff’s laws.

In simple terms, Kirchhoff’s laws are really an expression of conservation of energy. Kirchhoff’s current law (KCL) says that the current going into a single point (a node) has to have exactly the same amount of current going out of it. If you are more mathematical, you can say that the sum of the current going in and the current going out will always be zero, since the current going out will have a negative sign compared to the current going in.

You know the current in a series circuit is always the same, right? For example, in a circuit with a battery, an LED, and a resistor, the LED and the resistor will have the same current in them. That’s KCL. The current going into the resistor better be the same as the current going out of it and into the LED.

This is mostly interesting when there are more than two wires going into one point. If a battery drives 3 magically-identical light bulbs, for instance, then each bulb will get one-third of the total current. The node where the battery’s wire joins with the leads to the 3 bulbs is the node. All the current coming in, has to equal all the current going out. Even if the bulbs are not identical, the totals will still be equal. So if you know any three values, you can compute the fourth.

If you want to play with it yourself, you can simulate the circuit below.

The current from the battery has to equal the current going into the battery. The two resistors at the extreme left and right have the same current through them (1.56 mA). Within rounding error of the simulator, each branch of the split has its share of the total (note the bottom leg has 3K total resistance and, thus, carries less current).

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On Point: The Yagi Antenna

May 24, 2017 by Dan Maloney 86 Comments

If you happened to look up during a drive down a suburban street in the US anytime during the 60s or 70s, you’ll no doubt have noticed a forest of TV antennas. When over-the-air TV was the only option, people went to great lengths to haul in signals, with antennas of sometimes massive proportions flying over rooftops.

Outdoor antennas all but disappeared over the last third of the 20th century as cable providers became dominant, cast to the curb as unsightly relics of a sad and bygone era of limited choices and poor reception. But now ~~cheapskates~~ cable-cutters like yours truly are starting to regrow that once-thick forest, this time lofting antennas to receive digital programming over the air. Many of the new antennas make outrageous claims about performance or tout that they’re designed specifically for HDTV. It’s all marketing nonsense, of course, because then as now, almost every TV antenna is just some form of the classic Yagi design. The physics of this antenna are fascinating, as is the story of how the antenna was invented.

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A Few Of Our Favorite Chips: 4051 Analog Mux

May 17, 2017 by Elliot Williams 57 Comments

Raindrops on roses, and whiskers on kittens? They’re alright, I suppose. But when it comes down to it, I’d probably rather have a bunch of 4051, 4052, and 4053 analog multiplexers on the component shelf. Why? Because the ability to switch analog signals around, routing them at will, under control of a microcontroller is tremendously powerful.

Whether you want to read a capacitive-sensing keyboard or just switch among audio signals, nothing beats a mux! Read on and see if you agree.

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If The I And Q Of Software Defined Radio Are Your Nemesis, Read On

May 16, 2017 by Jenny List 30 Comments

For those of us whose interests lie in radio, encountering our first software defined radio must have universally seemed like a miracle. Here is a surprisingly simple device, essentially a clever mixer and a set of analogue-to-digital or digital-to-analogue converters, that can import all the complex and tricky-to-set-up parts of a traditional radio to a computer, in which all signal procession can be done using software.

A quadrature mixer. Jugandi (Public domain).

When your curiosity gets the better of you and you start to peer into the workings of a software defined radio though, you encounter something you won’t have seen before in a traditional radio. There are two mixers fed by a two local oscillators on the same frequency but with a 90 degree phase shift, and in a receiver the resulting mixer products are fed into two separate ADCs. You encounter the letters I and Q in relation to these two signal paths, and wonder what on earth all that means.

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