Count Your Fans With This Stylish ESP8266 Display

February 8, 2018 by 15 Comments

Continuous self-affirmation is a vital component to the modern lifestyle. Of course you know the world loves you, but exactly how much do they love you? Checking your phone every few minutes to see if you’ve gained any followers is gauche, and perhaps more to the point, doesn’t let you show off when you’ve got visitors over. In the modern era, the up-and-coming social media star needs a stylish way to display just how popular they are for the world to see.

That’s the idea behind this very slick social media counter created by [Becky Stern]. Built into a standard shadow box frame and using LED displays glowing through a printed piece of paper, the finished product looks more like modern art than the usual hacker fare.

The counter is powered by a NodeMCU, but you could drop in your favorite variant of the ESP8266 and things would work more or less the same. For the displays, [Becky] is using four Adafruit 7-Segment LED modules, which are easily controlled via I2C which keeps the wiring to a minimum.

It’s interesting to note that since her follower count on Twitter has already hit five digits, two of the display modules are used next to each other for that particular service. Her Instructables and Instagram counters only have one display each however, limiting her counts on those services to 9,999 each. There’s probably something to be learned here in terms of the relative follower counts you can expect on the different social networks if you’re targeting your content to the hacker and maker crowd, but we’ll leave the analysis to those with a better handle on such matters.

Hardware aside, [Becky] spends a lot of time in the video talking about the code she’s come up with to pull her stats from the various services and push them out to the LED displays at a regular interval. It’s nice to see so much attention and explanation given to the software side of a project like this, as more often than not you’re left to your own to figure out what the source code is doing.

This project is quite similar to the YouTube Play Button hack we covered a few months back, but the addition of multiple social networks in one device is a nice improvement over the basic concept.

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Build A Tiny Hot Wire Foam Cutter

February 8, 2018 by 34 Comments

Let’s face it: cutting foam with a knife, even a serrated plastic knife meant for the job, is a messy pain in the ass.  This is as true for insulation board as it is for the ubiquitous expanded polystyrene kind of foam used for everything from coffee cups to packaging material.

Those stick-type hot wire cutters from the craft store that plug into the wall aren’t much better than a knife. The actual cleaving of foam is easier, but dragging a long, hot flexible wand through rigid foam just right, without making burn marks, is pretty frustrating. It’s not like you can hold the other end to keep it steady. A foam cutter built like a coping saw but held parallel to the wire would offer much better control.

[Techgenie]’s handheld hot wire foam cutter is a simple build based on a single 18650 and a piece of nichrome wire. While this is probably not the most Earth-shattering hack you’ll see today, it’s a useful tool that can be made in minutes with items on hand. Laptop chargers are full of 18650s, and nichrome wire can be sourced from old toasters, hair dryers, or space heaters.

You shouldn’t use just any old wire for this, though, or the battery will get hot and potentially explode. Nichrome wire has a high resistance, and that’s exactly what you want in a tool that essentially shorts a battery to make heat. [Techgenie] used a momentary button instead of a switch, which is a good way to stay safe while using it. It wouldn’t hurt to add some protection circuitry and take the battery out when you’re done. Burn past the break to watch him build it and cut a few tight turns with ease.

If you have bigger, more complicated foam-cutting jobs in mind, why not build a CNC version out of e-waste?

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Large Format… Videography?

February 8, 2018 by 41 Comments

Large format photography gives a special quality to the images it produces, due to the differences in depth of field and resolution between it and its more modern handheld equivalents. Projecting an image the size of a dinner plate rather than a postage stamp has a few drawbacks though when it comes to digital photography, sensor manufacturersdo not manufacture consumer products at that size.

[Zev Hoover] has created a large format digital camera, and is using it not only for still images but for video. And it’s an interesting device, for the way he’s translated a huge large-format image into a relatively small sensor in a modern SLR. He’s projecting the image from the large-format lens and bellows onto a screen made from an artist’s palette, a conveniently available piece of bright white plastic, and capturing that image with his SLR mounted beneath the large-format lens assembly. This would normally cause a perspective distortion, but to correct that he’s mounted his SLR lens at an offset.

He does point out that since less light reaches the camera there is also a change in the ISO setting on the camera, but once that has been taken into account it performs satisfactorily. The result is a camera that allows something rather unusual, for Victorian-style large-format images to come to life as video. He demonstrates it in the video below, complete with friends in suitably old-fashioned looking steampunk attire.

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How Current Shunts Work

February 8, 2018 by 55 Comments

Current. Too little of it, and you can’t get where you’re going, too much and your hardware’s on fire. In many projects, it’s desirable to know just how much current is being drawn, and even more desirable to limit it to avoid catastrophic destruction. The humble current shunt is an excellent way to do just that.

Ohm’s Law.

To understand current, it’s important to understand Ohm’s Law, which defines the relationship between current, voltage, and resistance. If we know two out of the three, we can calculate the unknown. This is the underlying principle behind the current shunt. A current flows through a resistor, and the voltage drop across the resistor is measured. If the resistance also is known, the current can be calculated with the equation I=V/R.

This simple fact can be used to great effect. As an example, consider a microcontroller used to control a DC motor with a transistor controlled by a PWM output. A known resistance is placed inline with the motor and, the voltage drop across it measured with the onboard analog-to-digital converter. With a few lines of code, it’s simple for the microcontroller to calculate the current flowing to the motor. Armed with this knowledge, code can be crafted to limit the motor current draw for such purposes as avoiding overheating the motor, or to protect the drive transistors from failure.

In fact, such strategies can be used in a wide variety of applications. In microcontroller projects you can measure as many currents as you have spare ADC channels and time. Whether you’re driving high power LEDs or trying to build protection into a power supply, current shunts are key to doing this.

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Electric Snowblower Does The Job With 240 Volts

February 8, 2018 by 89 Comments

In parts of the world where it snows a lot and there are requirements for homeowners to keep sidewalks clear, a personal snowblower is it seems an essential piece of equipment. They have traditionally used internal combustion engines, but electric models are also available.

[Joel Clemens] is not impressed by the commercial electric blowers available to him as an American, because their 120 V mains supply just can’t deliver the power to make an effective two-stage design. So he’s built his own using a formerly gasoline-powered blower from a garage sale, and a 240 V industrial motor.

The blower is an impressive piece of equipment even if his running it close to its own cord does look rather hazardous. But the video is also of interest for its examination of the state of access to 240 V outlets for Americans. [Joel] has one for his electric vehicles, and has made a splitter box to give him the required American-style 240 V industrial connector. He makes the point that this is becoming more common as the take-up of electric vehicles gathers pace.

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Ball and socket helping hands

Printed It: Do More With Lockable Ball And Socket Helping Hands

February 8, 2018 by 28 Comments

In one hand you hold the soldering iron, in the other the solder, and in two more hands the parts you’re trying to solder together. Clearly this is a case where helping hands could be useful.

Magnifying glass with helping hands
Magnifying glass with helping hands

Luckily helping hands are easy to make, coolant hoses will do the job at under $10. Attach alligator clips to one end, mount them on some sort of base, and you’re done. Alternatively, you can steal the legs from an “octopus” tripod normally used for cell phones. So why would you 3D print them?

One reason is to take advantage of standardized, open source creativity. Anyone can share a model of their design for all to use as is, or to modify for their needs. A case in point is the ball and socket model which I downloaded for a helping hand. I then drew up and printed a magnifying glass holder with a matching socket, made a variation of the ball and socket joint, and came up with a magnetic holder with matching ball. Let’s takea  look at what worked well and what didn’t.

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The Tachometer Inside Your Smartphone

February 8, 2018 by 26 Comments

It’s the latest in instrumentation for the well-appointed shop — an acoustically coupled fast Fourier transform tachometer. Sounds expensive, but it’s really just using a smartphone spectrum analyzer app to indirectly measure tool speeds. And it looks like it could be incredibly handy.

Normally, non-contact tachometers are optically coupled, using photoreceptors to measure light flashing off of a shaft or a tool. But that requires a clear view of the machine, often putting hands far too close to the danger zone. [Matthias Wandel]’s method doesn’t require line of sight because it relies on a cheap spectrum analyzer app to listen to a machine’s sound. The software displays peaks at various frequencies, and with a little analysis and some simple math, the shaft speed of the machine can be determined. [Matthias] explains how to exclude harmonics, where to find power line hum, isolating commutator artifacts, and how to do all the calculations. You’ll need to know a little about your tooling to get the right RPM, and obviously you’ll be limited by the audio frequency response of your phone or tablet. But we think this is a great tip.

[Matthias] is no stranger to shop innovations and putting technology to work in simple but elegant ways. We wonder if spectrum analysis could be used to find harmonics and help with his vibration damping solution for a contractor table saw.

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