Misc Hacks

Reverse Engineering CMOS

October 18, 2018 by 6 Comments

ICs have certainly changed electronics, but how much do you really know about how they are built on the inside? While decapsulating and studying a modern CPU with 14 nanometer geometry is probably not a great first project, a simple 54HC00 logic gate is much larger and much easier to analyze, even at low magnification. [Robert Baruch] took a die image of the chip and worked out what was going on, and shares his analysis in a recent video. You can see that video, below.

The CMOS structures are simple because a MOSFET is so simple to make on an IC die. The single layer of aluminum conductors also makes things simple.

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DIY Arc Light Makes An Unnecessarily Powerful Bicycle Headlight

October 17, 2018 by 38 Comments

Remember when tricking out a bike with a headlight meant clamping a big, chrome, bullet-shaped light to your handlebar and bolting a small generator to your front fork? Turning on the headlight meant flipping the generator into contact with the front wheel, powering the incandescent bulb for the few feet it took for the drag thus introduced to grind you to a halt. This ridiculous arc-lamp bicycle headlight is not that. Not by a long shot.

We’re used to seeing [Alex] doing all manner of improbable, and sometimes impossible, things on his popular KREOSAN YouTube channel. And we’re also used to watching his videos in Russian, which detracts not a whit  from the entertainment value for Andglophones; subtitles are provided for the unadventurous, however. The electrodes for his arc light are graphite brushes from an electric streetcar, while the battery is an incredibly sketchy-looking collection of 98 18650 lithium-ion cells. A scary rat’s nest of coiled cable acts as a ballast to mitigate the effects of shorting when the arc is struck. The reflector is an old satellite TV dish covered in foil tape with the electrodes sitting in a makeshift holder where the feedhorn used to be. It’s bright, it’s noisy, it’s dangerous, and it smokes like a fiend, but we love it.

Mounting it to the front of the bike was just for fun, of course, and it works despite the janky nature of the construction. The neighbors into whose apartments the light was projected could not be reached for comment, but we assume they were as amused as we were.

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Dymo Rides Again With This Dot-Matrix Label Embosser

October 13, 2018 by 21 Comments

For a five-year-old future Hackaday scribe, there could be no greater day than that on which a Dymo label maker appeared in the house. With its spinny daisy-wheel to choose a character and its squeezy handle to emboss the letter into the plastic tape, there would follow a period of going nuts kerchunking out misspelled labels and slapping them on everything. Plus the things look like space guns, so there would have been a lot of pew-pewing too.

This Dymo dot-matrix label maker bears no resemblance to our long-lost label blaster, but it’s pretty cool in its own right. The product of collaborators [Felix Fisgus] and [Timo Johannes] and undertaken as a project for their digital media program, the only thing the labeler has in common with the Dymos of old is the tape. Where the manual labelers press the characters into the tape with a punch and die, their project uses a dot-matrix approach. Messages are composed on an old PS/2 keyboard through an Arduino and a 16×2 LCD display, and punched onto the tape a dot at a time. The punch is a large darning needle riding on the remains of an old CD drive and driven by a solenoid. When it comes time to cut the label, servo driven scissors do the job. It’s a noisy, crazy, Rube Goldberg affair, and we love it. Check it out in action in the video below.

We applaud [Felix] and [Timo] for carrying the torch of embossed label making. It’s a shame that we’ve turned to soulless thermal printers to handle most of our labeling needs; then again, we’ve seen some pretty neat hacks for those too.

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Homebrew Linear Actuators Put The Moves On This Motion Simulator

October 4, 2018 by 31 Comments

Breaking into the world of auto racing is easy. Step 1: Buy an expensive car. Step 2: Learn how to drive it without crashing. If you’re stuck at step 1, and things aren’t looking great for step 2 either, you might want to consider going with a virtual Porsche or Ferrari and spending your evenings driving virtual laps rather than real ones.

The trouble is, that can get a bit boring after a while, which is what this DIY motion simulator platform is meant to address. In a long series of posts with a load of build details, [pmvcda] goes through what he’s come up with so far on this work in progress. He’s building a Stewart platform, of the type we’ve seen before but on a much grander scale. This one will be large enough to hold a race car cockpit mockup, which explains the welded aluminum frame. We were most interested in the six custom-made linear actuators, though. Aluminum extrusions form the frame holding BLDC motor, and guide the nut of a long ball screw. There are a bunch of 3D-printed parts in the actuators, each of which is anchored to the frame and to the platform by simple universal joints. The actuators are a little on the loud side, but they’re fast and powerful, and they’ve got a great industrial look.

If car racing is not your thing and you’d rather build a full-motion flight simulator, here’s one that also uses DIY actuators.

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Pirates Don’t Stand a Chance Against This 3-D Printed Pan-Tilt Gimbal

October 2, 2018 by 11 Comments

Attention: No pirates maritime wealth redistribution agents were harmed in the making of the video below.

Some projects are for work, some are for fun, and some, like this entirely 3D-printed camera pan-tilt gimbal, start out as work and then turn into fun. As professional digital FX artist [FlorianH] tells the tale, he was in need of such a rig for some motion-control work. Buying off the shelf is always an option, except when it’s boring, so [Florian] invested an untold number of hours in front of Fusion 360 meticulously designing every last part, except for some bearings, the NEMA 17 steppers, and some fasteners. Ten One hundred hours of printing later and the device was ready for assembly and a quick test, which showed that this thing is smooth as silk.

And the pirate snuff-vid? That was just for fun, and we enjoyed it immensely. [Florian] assures us that none of the explosions were added in post; all are practical effects, done with flash cotton and a bit of powdered charcoal. We asked – you know, for reference.

We’ve featured lots of pan-tilt rigs before, using everything from hobby servos to purely mechanical linkages. But this one has a certain flair to it that we really like.

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How to Build an Inverter, and Why Not to Bother

September 30, 2018 by 30 Comments

It’s ridiculously easy to lay hands on a cheap DC-to-AC inverter these days. They’re in just about every discount or variety store and let you magically plug in mains powered devices where no outlets exist. Need 120- or 240-VAC in your car? No problem – a little unit that plugs into the lighter socket is available for a few bucks.

So are these commodity items worth building yourself? Probably not as [GreatScott!] explains, but learning how they work and what their limitations are will probably help your designs. The cheapest and most common inverters have modified square wave outputs, which yield a waveform that’s good enough for most electronics and avoids the extra expense of producing a pure sinusoidal output. He explains that the waveform is just a square wave with a slight delay at the zero-crossing points to achieve the stepped pattern, and shows a simple H-bridge circuit to produce it. He chose to drive the output section with an Arduino, to easily produce the zero-crossing delay. He uses this low-voltage inverter to demonstrate how much more complicated the design needs to get to overcome the spikes caused by inductive loads and the lack of feedback from the output.

Bottom line: it’s nice to know how inverters work, but some things are better bought than built. That won’t stop people from building them, of course, and knowing what you’re doing in this field has been worth big bucks in the past.

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Inductance in PCB Layout: The Good, the Bad, and the Fugly

September 28, 2018 by 35 Comments

When current flows through a conductor it becomes an inductor, when there is an inductor there is an electromagnetic field (EM). This can cause a variety of issues during PCB layout if you don’t plan properly, and sometimes we get burned even when we think we have planned for unwanted inductance and the effects that come with them.

When doing high speed logic we need to be able to deliver sudden changes in current to the devices if we want to have proper switching times and logic levels. Unfortunately inductance is usually not a friend in these circumstances as it resists those sudden changes in current. If the high speed devices are driving capacitive loads, which themselves are resisting changes in voltage, even more instantaneous current is needed.

Simply put, inductors resist a change of current, and can act as a low pass filter when in series with the signal or power supply flow. Inductors do this by storing energy in the flux surrounding the conductor. Alternatively capacitors resist a change in voltage (again by storing energy) and can act as a high pass filter when in series with the signal. This makes them a valuable tool in the fight against unwanted inductance in power supply distribution.

In the video below, and the remainder of this article, I’m going to dive into the concept of inductance and how it affects our design choices when laying out circuit boards.

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