What’s Inside A Scientology E-Meter?

July 19, 2018 by Brian Benchoff 146 Comments

This is something we’ve been waiting a very long time for. The Church of Scientology uses devices called E-Meters to measure Thetans in the body. We’re not going to discuss this further, because we don’t want to be murdered. In reality, the E-Meter is simply a device that costs five thousand dollars and only measures the resistance of the human body. It does this by having the subject hold two copper cylinders and a simple Wheatstone bridge. Why does the E-Meter cost five thousand dollars? As [Play With Junk] found out, it’s an exquisitely engineered piece of hardware.

[Play With Junk] acquired this E-Meter from eBay for something around $100, and from a system-level analysis, it’s really not anything special. There’s a fancy analog meter, yes, but most of this wouldn’t be out of place in any 90s-era piece of test equipment. There’s an 8051 microcontroller reading what are probably some fancy ADCs, and there’s an LCD driver on board. Slap it in a fancy injection-molded case, and you have an E-Meter.

What’s most impressive is the quality of the components that go into a machine that effectively only measures the resistance of the human body. The ‘trim’ pot is a Vishay wire-wound precision potentiometer that costs somewhere between $20 and $60. The power switch is an over-specced switch that probably costs $5. The control pots look and feel great, and the wiring is wrapped around chokes.

This is an exceptionally well-engineered device, and it shows. There’s an incredible amount of work that went into the electronics, and a massive amount of money that went into the fancy injection molded enclosure. If you’re looking for an example of a well-engineered tool, price be damned, you need only look at an E-Meter.

Check out the video below of the entire teardown.

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A Farewell To Printrbot

July 19, 2018 by Tom Nardi 71 Comments

It’s with a heavy heart that we must report Printrbot has announced they are ceasing operations. Founded in 2011 after a wildly successful Kickstarter campaign, the company set out to make 3D printing cheaper and easier. Their first printer was an amalgamation of printed parts and wood that at the time offered an incredible deal; when the Makerbot CupCake was selling for $750 and took 20+ hours to assemble, the Printrbot kit would only run you $500 and could be built in under an hour.

Printrbot got their foot in the door early, but the competition wasn’t far behind. The dream of Star Trek style replicators fueled massive investment, and for a while it seemed like everyone was getting into the 3D printing game. Kit built machines gave way to turn-key printers, and the prices starting coming down. Printrbot’s products evolved as well, dropping wood in favor of folded steel and pioneering impressive features like automatic bed leveling. In 2014 they released the Printbot Simple Metal, which ultimately became their flagship product and in many ways represents the high water mark for the company.

Eventually, overseas manufacturers saw an opportunity and started flooding the market with 3D printers that were cheaper than what many would have believed possible only a few years earlier. Today you can go online and buy a perfectly serviceable starter printer for under $200, even less if you’re still willing to build it yourself. For an American company like Printrbot, competing at this price point was simply an impossibility.

Rather than give up, Brook decided to take things in a different direction. If he couldn’t compete with imported machines on price, he would start building high end printers. A new version of the Simple Metal was introduced in 2016 with premium features such as linear rails and cloud-based slicing, complete with a premium price. From that point on, most new Printrbot products would release at over $1,000; putting them more in line with “prosumer” machines from companies like Ultimaker. For hacker types who got their first taste of 3D printing thanks to a cheap wooden Printrbot kit, this was something of a bittersweet moment.

At the same time, Brook’s natural hacker spirit and love of the open source community lead to a number of interesting side projects that never quite got off the ground. Most recently, he’d been putting the finishing touches on the Printrbelt, a 3D printer with a conveyor belt in place of a traditional bed. Such a machine could finally bridge the gap between desktop 3D printing and true small scale production capability.

When we saw Brook at the East Coast RepRap Festival, he brought along a new machine that the more cynical observer might have taken as foreshadowing. The Printrbot Easy was going to be a modified and rebranded FlashForge Finder, a final acknowledgement that the only way to compete with the Chinese manufactured 3D printers was to sell one of your own.

It’s always sad to see a tech company go under, but seeing the end of Printrbot is especially hard. Built in America with locally sourced components and with a commitment to keeping their machines open source, there was a lot to love about the plucky little 3D printer company from Lincoln, California. Printrbot was the quintessential hacker success story, and we’re proud to say we’ve been in their corner from the start. Here’s to wishing Brook Drumm and the entire Printrbot team success in their future endeavors; we’ll be keeping an eye out.

Twitch Stream Turned Infinity Mirror

July 18, 2018 by Tom Nardi 6 Comments

Most Hackaday readers are likely to be familiar with the infinity mirror, a piece of home decor so awesome that Spock still has one up on the wall in 2285. The idea is simple: two parallel mirrors bounce and image back and forth, which creates a duplicate reflection that seems to recede away into infinity. A digital version of this effect can be observed if you point a webcam at the screen that’s displaying the camera’s output. The image will appear to go on forever, and the trick provided untold minutes of fun during that period in the late 1990’s where it seemed everyone had a softball-shaped camera perched on their CRT monitors.

While you might think you’ve already seen every possible variation of this classic visual trick, [Matt Nishi-Broach] recently wrote in to tell us about an infinity mirror effect he’s created using the popular streaming platform Twitch. The public is even invited to fiddle with the visuals through a set of commands that can be used in the chat window.

It works about how you’d expect: the stream is captured, manipulated through various filters, and then rebroadcast through Twitch. This leads to all sorts of weird visual effects, but in general gives the impression that everything is radiating from a central point in the distance.

While [Matt] acknowledges that there are probably not a lot of other people looking to setup their own Twitch feedback loops, he’s still made his Python code available for anyone who might be interested. There’s a special place in Hacker Valhalla for those who release niche software like this as open source. They’re the real MVPs.

If you’d like to get started on your infinite journey with something a bit more physical, we’ve covered traditional infinity mirror builds ranging from the simplistic to the gloriously over-engineered.

Understanding Math Vs Understanding Math

July 18, 2018 by Al Williams 26 Comments

One of the things hard about engineering — electrical engineering, in particular — is that you can’t really visualize what’s important. Sure, you can see a resistor and an LED in your hands, but the real stuff that we care about — electron flow, space charge, and all that — is totally abstract. If you just tinker, you might avoid a lot of the inherent math (or maths for our UK friends), but if you decide to get serious, you’ll quickly find yourself in a numerical quicksand. The problem is, there’s mechanically understanding math, and intuitively understanding math. We recently came across a simple site that tries to help with the latter that deserves a look.

If you don’t know what we mean by that, consider a simple example. You can teach a kid that 5×3 is 15. But, hopefully, a teacher at some point in your academic career pointed out to you what the meaning of it was. That if you had five packages of three items, you have 15 items total. Or that if you have a room that is five feet on one side and three feet on the other, the square footage is 15 square feet.

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Harley-Hardened Wire Helps High-Gain Antenna Hack

July 18, 2018 by Dan Maloney 46 Comments

What does a Harley-Davidson motorcycle have to do with building antennas? Absolutely nothing, unless you happen to have one and need to work-harden copper wire to build a collinear antenna for LoRa.

We’ll explain. Never being one to settle, [Andreas Spiess] needed a better antenna for his LoRa experiments. Looking for high gain and an omnidirectional pattern, he bought a commercial colinear antenna, which is a wire with precisely spaced loops that acts like a stack of dipoles. Sadly, in a head-to-head test [Andreas] found that the commercial antenna was no better than lower gain antennas in terms of range, and so he decided to roll his own.

Copper wire is a great material for antennas since it can be easily formed without special tools and it solders like a champ. But the stuff you get at the home center is nowhere near stiff enough for a free-standing vertical whip. This is where the Harley came in: [Andreas] used his Hog to stretch out the 1.75-mm diameter (a little bigger than #14 AWG) copper wire. Not only did the work-hardening stiffen the wire, it reduced its diameter to the 1.4 mm needed for the antenna design. His vector network analyzer told him that ground-plane elements and a little fiddling with the loop diameter were needed to get the antenna to resonate at 868 MHz, but in the end it looks like the antenna is on track to deliver 5-dBi of gain.

Of course there are plenty of other ways to stretch out a wire — you could just stretch it out with hanging weights, or even with a go-kart motor-powered winch if you’re ambitious. But if you’ve got a bike like that, why not flaunt it?

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3D Printed Gun Saga: Court Case Over CAD Files Settled

July 18, 2018 by Mike Szczys 88 Comments

Can you create 3D printed designs and distribute them freely and without restriction? Maybe, and it’s likely to become easier in the future. A settlement has been reached in the saga of the US Department of State versus Cody Wilson, and beginning August 1st the Defense Distributed library of gun designs will once again become available.

Cody is well known for creating the first 3D printed gun. He went on to found Defense Distributed, a company that published designs and technical files for 3D printing firearms before being pulled into litigation that sought to curb the distribution of such plans by subjecting them to International Traffic in Arms Regulations (ITAR) restrictions. Read that carefully, it’s the (international) distribution of CAD files at question here, and not the act of 3D printing, and Defense Distributed has been granted an ITAR exemption. Will other arms-related design files be similarly exempted? The settlement mentions upcoming rule changes seeking to make this type of exemption the standard.

As members of the Hackaday community, we’re the people to whom our friends and family turn for perspective when new technology makes it into their news feeds. Those with little or no exposure to 3D printing may easily fall to doom and gloom reports. But is this a story of doom and gloom? Absolutely not, guns are still guns and 3D printers are still 3D printers. Let’s take a look.

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Dual Brushed Motor Controller Doesn’t Care How It Receives Commands

July 18, 2018 by Ben James 3 Comments

The simple DC brushed motor is at the heart of many a robotics project. For making little toy bots that zip around the house, you can’t beat the price and simplicity of a pair of brushed motors. They’re also easy to control; you could roll your own H-bridge out of discrete transistors, or pick up one of the commonly used ICs like the L298N or L9110S.

But what if you want an all-in-one solution? Something that will deliver enough current for most applications, drive dual motors, and deal with a wide range of input voltages. Most importantly, something that will talk to any kind of input source. For his Hackaday prize entry, [Praveen Kumar] is creating a dual brushed motor controller which can handle a multitude of input types. Whether you’re using an IR remote, a Pi communicating over I2C, an analog output or Bluetooth receiver, this driver can handle them all and will automatically select the correct input source.

The board has an ATmega328p brain, so Arduino compatibility is there for easy reprogramming if needed. The mounting holes and header locations are also positioned to allow easy stacking with a Pi, and there’s a status LED too. It’s a great module that could easily find a place in a lot of builds.

If you need even more control over your brushed motor, you can soup up its capabilities by adding a PID loop for extra smarts.