Juicero: A Lesson On When To Engineer Less

Ben Einstein, a product designer and founder at Bolt, a hardware-based VC, recently got his hands on a Juicero press. This desktop juice press that only works with proprietary pouches filled with chopped fruits and vegetables is currently bandied in the tech press as evidence Silicon Valley has gone mad, there is no future in building hardware, and the Internet of Things is a pox on civilization. Hey, at least they got the last one right.

This iFixit-style tear down digs into the Juicero mixer in all its gory details. It’s beautiful, it’s a marvel of technology, and given the engineering that went into this machine, it was doomed to fail. Not because it didn’t accomplish the task at hand, but because it does so with a level of engineering overkill that’s delightful to look at but devastating to the production cost.

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Measuring Capacitors at the Birth of Rock and Roll

The late 1950s [Bill Haley], [Elvis Presley], and [Little Richard] were building a new kind of music. Meanwhile, electronic hobbyists were building their own gear from Heathkit. A lot of that gear shows you how far we’ve come in less than a century. [Jeff Tranter’s] YouTube channel is a great way to look at a lot of old Heathkit gear, including this really interesting “direct reading capacity meter.” You can see the video, below.

Measuring capacitance these days is easy. Many digital multimeters have that function. However, those didn’t exist in the 1950s–at least, not in the way we know them. The CM-1 weighed 5 pounds, had several tubes, and cost what would equate to $250 in today’s prices. Unlike other instruments of the day, though, the capacitance was read directly off a large analog meter (hence, the name). You didn’t have to interpret readings using a nomograph or move a knob to balance a bridge and read the knob’s position.

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The Shocking Truth About Transformerless Power Supplies

Transformerless power supplies are showing up a lot here on Hackaday, especially in inexpensive products where the cost of a transformer would add significantly to the BOM. But transformerless power supplies are a double-edged sword. That title? Not clickbait. Poking around in a transformerless-powered device can turn your oscilloscope into a smoking pile or get you electrocuted if you don’t understand them and take proper safety precautions.

But this isn’t a scare piece. Transformerless designs are great in their proper place, and you’re probably going to encounter one someday because they’re in everything from LED lightbulbs to IoT WiFi switches. We’re going to look at how they work, and how to design and work on them safely, because you never know when you might want to hack on one.

Here’s the punchline: transformerless power supplies are safely useable only in situations where the entire device can be enclosed and nobody can accidentally come in contact with any part of it. That means no physical electrical connections in or out — RF and IR are fair game. And when you work with one, you have to know that any part of the circuit can be at mains voltage. Now read on to see why!

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Stereo Microscope Teardown

Stereo microscopes are very handy tools, especially for a lot of hackers who now regularly assemble, test and debug SMD circuits using parts as small as grains of sand. We have seen a lot of stereo microscope hacks here at Hackaday, so it helps to take a look inside one to understand how they work. Thanks to [noq2]’s teardown of a Wild Heerbrugg model M8 stereo microscope, we get to do exactly that. His M8 is from the mid-1970s, but it is in mint condition and doesn’t look like it’s over 40 years old. Despite being so old, [noq2] still uses it regularly, so the teardown is not super detailed. But there’s enough for us to get a good idea of how they work.

Stereo microscopes use one of two optical designs — the Common Main Objective (CMO) optical system and the Greenough optical system. [MicroscopeWorld] has a nice blog post explaining these two types and their pros and cons. Not surprisingly, stereo microscopes, just like other optical instruments, are highly modular to allow attaching various extensions, adapters and accessories. The Wild M8 uses the CMO design and its main parts are the binocular head, the main body and the objective lens.

The binocular head consists of the two eyepieces and a pair of prisms that create the binocular split. The alignment of these prisms is critical and they must not be disturbed in their mounting cages. The prism cages have a sliding adjustment to help set the interpupillary distance. The main body contains the zoom and magnification optics and the related mechanics. [noq2] is impressed with the lack of plastics used in the construction of these fine instruments. Finally, there’s the huge objective lens, which [noq2] feels is the Achilles heel of the instrument. Its design is not plan-apochromatic and that causes significant chromatic aberrations, especially when trying to capture photographs. Thankfully, there are other objective lenses which can be used, including some DIY adapter solutions. The Wild Heerbrugg brand was taken over by Leica who still produce a range of stereo microscopes under that badge. If you have one of these microscopes, [noq2] suggests you head over the French forum at lenaturaliste.net where you’ll find extensive information about them.

As a bonus, also check out [noq2]’s ghetto lighting solution for his microscope – a pair of high power LED’s attached to salvaged heatsinks, and mounted on the frame of an old 80 mm cooling fan. The fan frame is perfect since it is the right size to slide over the objective lens. If you’re looking for a more capable lighting solution for your microscope, then check out “AZIZ! Light!”, a microscope ring light with a number of different features.

Before There were Nixie Tubes, There Were Edge-Lit Displays?

We’ve seen a bunch of replacements for nixie tubes using LEDs and edge-lit acrylic for the numbers. But one of the earliest digital voltmeters used edge-lit Lucite plates for the numbers and a lot of incandescent lamps to light them up.

[stevenjohnson] has a Non-Linear Systems Model 481 digital voltmeter and he’s done a teardown of it so we can get a glimpse of the insides. Again, anyone who’s seen the modern versions of edge-lit numeric displays knows what they are: A series of clear plastic plates with numbers (or characters) etched into them, each with a light source beneath them. You turn one light on to light one plate, another to light another, and so on. The interesting bit here is the use of incandescent bulbs and the use of sequential relays to cycle through the lights. The relays make a lot of racket, especially with the case open.

[stevenjohnson] also notes that he might have made a mistake opening up the part of the machine where the plates are stored as it took him a bit to get the plates back in place and back in the unit. We’d imagine it was pretty loud if you were taking a lot of measurements with this machine, although it looks great inside and, obviously, the idea is a pretty good one. Check out this edge-lit nixie tube display or these edge-lit numeric modules.

[via boingboing]

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The Hard Way of Cassette Tape Auto-Reverse

The audio cassette is an audio format that presented a variety of engineering challenges during its tenure. One of the biggest at the time was that listeners had to physically remove the cassette and flip it over to listen to the full recording. Over the years, manufacturers developed a variety of “auto-reverse” systems that allowed a cassette deck to play a full tape without user intervention. This video covers how Akai did it – the hard way.

Towards the end of the cassette era, most manufacturers had decided on a relatively simple system of having the head assembly rotate while reversing the motor direction. Many years prior to this, however, Akai’s system involved a shuttle which carried the tape up to a rotating arm that flipped the cassette, before shuttling it back down and reinserting it into the deck.

Even a regular cassette player has an astounding level of complexity using simple electromechanical components — the humble cassette precedes the widespread introduction of integrated circuits, so things were done with motors, cams, levers, and switches instead. This device takes it to another level, and [Techmoan] does a great job of showing it in close-up detail. This is certainly a formidable design from an era that’s beginning to fade into history.

The video (found after the break) also does a great job of showing glimpses of other creative auto-reverse solutions — including one from Phillips that appears to rely on bouncing tapes through something vaguely resembling a playground slide. We’d love to see that one in action, too.

One thing you should never do with a cassette deck like this is use it with a cassette audio adapter like this one.

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Teardown of Nike Self-Lacing Shoes

There used to be a time, before running shoes had blinking LEDs and required placing on an inductive charger overnight, when we weren’t worried about whether or not we could dump the firmware running underneath our heels. Those are not the times that we’re living in. Nike came out with a shoe that solves the age-old problem of lacing: the HyperAdapt. And [Telind Bench] has torn them apart.

img_0059Honestly, we’re kinda “meh” about what’s inside. The “laces” are actually tubes with a small Kevlar-like cable running inside, and the whole thing torques up using a small, geared DC motor. That’s kinda cool. (We have real doubts about [Telind]’s guess of 36,000 RPM for the motor speed.) But in an age when Amazon gives away small WiFi-enabled devices for a few bucks as a loss-leader to get you to order a particular brand of laundry detergent, we’re not so dazzled by the technology here, especially not at the price of $720 for a pair of freaking shoes.

The only really interesting bit is the microcontroller, which is over-powered for the job of turning a wheel when a keyboard-style sensor is pressed by your heel. What is Nike thinking? We want to see the firmware, and we’d like it reverse engineered. What other chips are on board? Surely, they’ve got an accelerometer and are measuring your steps, probably tying in with an exercise app or something. Does anyone have more (technical) detail about these things? Want to make a name for yourself with a little stunt hacking?