Teardown Of A Fingerprint Padlock

We wouldn’t mind tearing down a fingerprint scanner, but we hate to bust up our expensive laptop or cell phone. [Julian], however, got a hold of a fingerprint scanning padlock and was willing to tear it apart for our benefit. The video appears below.

The padlock is a simple enough little device with a cable lock instead of a solid metal shackle, although we have seen similar devices with traditional shackles. Initially, the lock’s fingerprint storage is empty and it will open for any fingerprint. The first task is to set an administrator fingerprint. You’ll need that fingerprint to set up other fingerprints or to reset the unit. Of course, what we are really interested in is what’s inside.

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What’s Inside A Scientology E-Meter?

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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Teardown Of Sonos And Amazon Smart Speakers Reveals Interesting Engineering Details

Taking things apart is always fun, and this What Cracking Open a Sonos One Tells Us About the Sonos IPO”>excellent writeup of a teardown of a Sonos and Amazon smart speaker by [Ben Einstein] shows what you can learn. [Ben] is a Venture Capitalist and engineer, so much of his write up focuses on what the devices say about how the company spends money. There are plenty of things to learn for hackers, though: he details how the Sonos One uses a PCI daughterboard for wireless communications, while the Amazon Echo has a programmable radio on the main board.

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Dive Inside This Old Quartz Watch

In an age of smartwatches, an analog watch might seem a little old-fashioned. Whether it’s powered by springs or a battery, though, the machinery that spins those little hands is pretty fascinating. Trouble is, taking one apart usually doesn’t reveal too much about their tiny workings, unless you get up close and personal like with this microscopic tour of an analog watch.

This one might seem like a bit of a departure from [electronupdate]’s usual explorations of the dies within various chips, but fear not, for this watch has an electronic movement. The gross anatomy is simple: a battery, a coil for a tiny stepper motor, and the gears needed to rotate the hands. But the driver chip is where the action is. With some beautiful die shots, [electronupdate] walks us through the various areas of the chip – the oscillator, the 15-stage divider cascade that changes the 32.768 kHz signal to a 1 Hz pulse, and a remarkably tiny H-bridge for running the stepper. We found that last section particularly lovely, and always enjoy seeing the structures traced out. There are even some great tips about using GIMP for image processing. Check out the video after the break.

[electronupdate] knows his way around a die, and he’s a great silicon tour guide, whether it’s the guts of an SMT inductor or a Neopixel close-up. He’s also looking to improve his teardowns with a lapping machine, but there are a few problems with that one so far.

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An Electromagnet Brings Harmony to this Waving Cat

We’ve noticed waving cats in restaurants and stores for years, but even the happy bobbing of their arm didn’t really catch our attention. Maybe [Josh] had seen a couple more than we have when it occurred to him to take one apart to see how they work. They are designed to run indoors from unreliable light sources and seem to bob along forever. How do the ubiquitous maneki-neko get endless mechanical motion from one tiny solar cell?

Perhaps unsurprisingly given the prevalence and cost of these devices, the answer is quite simple. The key interaction is between a permanent magnet mounted to the end of the waving arm/pendulum and a many-turn wire coil attached to the body. As the magnet swings over the coil, its movement induces a voltage. A small blob of analog circuitry reacts by running current through the coil. The end effect is that it “senses” the magnet passing by and gives it a little push to keep things moving. As long as there is light the circuit can keep pushing and the pendulum swings forever. If it happens to stop a jolt from the coil starts the pendulum swinging and the rest of the circuit takes over again. [Josh] points to a similar circuit with a very nice write up in an issue of Nuts and Volts for more detail.

We’ve covered [Josh]’s toy teardowns before and always find this category of device particularly interesting. Toys and gadgets like the maneki-neko are often governed by razor-thin profit margins and as such must satisfy an extremely challenging intersection of product constraints, combining simple design and fabrication with just enough reliability to not be a complete disappointment.

For more, watch [Josh] describe his method in person after the break, or try flashing his code to an Arduino and make a waving cat of your own.

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Teardown: LED Bulb Yields Tiny UPS

Occasionally you run across a product that you just know is simply too good to be true. You might not know why, but you’ve got a hunch that what the bombastic phrasing on the package is telling you just doesn’t quite align with reality. That’s the feeling I got recently when I spotted the “LED intellibulb Battery Backup” bulb by Feit Electric. For around $12 USD at Home Depot, the box promises the purchaser will “Never be in the dark again”, and that the bulb will continue to work normally for up to 3.5 hours when the power is out. If I could repurpose that to make a tiny UPS for a microcontroller project of my own, it could be even more useful.

Now an LED light bulb with a battery in the base isn’t exactly rocket science, we can understand the product conceptually at a glance. But as they say, the devil is in the details. The box claims the bulb consumes 8.5 watts, but a battery with enough capacity to run such a load for 3.5 hours would be far too large to fit inside of a light bulb. Obviously there’s more to the story.

On the side of the box, in the smallest font used on the whole package, we get our clue. The bulb drops down to 200 lumens when in battery backup mode, or roughly as bright as a cheap LED flashlight. Now things are starting to come together. Without even opening the device, we can be fairly sure it will contain two separate arrays of LEDs: one low set for battery, and a brighter set to run when the bulb has AC power.

Still, I tend to be of the opinion that anything less than $20 or so is worth cracking open to see what makes it tick. Even if the product itself is underwhelming, there’s a chance the internal components could be useful or interesting. With that in mind, let’s see what’s inside a battery backup light bulb, and what we might be able to do with it.

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Polaroid Gets Thermal Printer and Raspberry Pi

Despite what you may have read in the comments, we here at Hackaday are not unaware that there’s something of a “Pi Fatigue” brewing. Similar to how “Arduino” was once a dirty word around these parts, projects that are built around the world’s most popular Linux SBC are occasionally getting dismissed as lazy. Hacker crams Raspberry Pi into an old electronic device, applies hot glue liberally, posts a gallery on Imgur, and boom! Lather, rinse, repeat.

We only mention this because the following project, despite featuring the Raspberry Pi Zero grafted into a vintage Polaroid camera, is anything but lazy. In the impeccably detailed and photographed write-up, [mitxela] explains how the Pi Zero and a thermal camera recreated the classic Polaroid experience of going from shutter button to physical picture in seconds. The workmanship and attention to detail on this build is simply phenomenal, and should quell any doubts our Dear Readers may have about Raspberry Pi projects. For now, anyway.

The video after the break will show you the modded camera in operation and goes over a few highlights of the build, but for this one you really should take the time to read the entire process start to finish. [mitxela] starts off by disassembling the Polaroid camera, complete with plenty of fantastic pictures that show how this legendary piece of consumer electronics was put together. If you’ve never seen the inside of one of these cameras, you might be surprised to see what kind of interesting hardware is lurking underneath that rather unassuming exterior. From the screw-less construction to the circuits with paper substrate, a lot of fascinating engineering went into getting this camera to a mass-market price. Frankly, the teardown alone is worth checking out.

But once the camera has been stripped down to the bare frame, the real fun begins. At the conceptual level, [mitxela] replaces the camera optics with a cheap webcam, the “brains” with a Raspberry Pi Zero, and the film mechanism with the type of thermal printer used for receipts. But how he got it all connected is why this project is so impressive. Nearly every decision made during the design and construction of this camera was for the purposes of reducing boot-time. Nobody wants a camera that takes 30, 15, or even 10 seconds to boot. It has to be available as soon as you need it.

Getting this Linux-powered camera boot up in as little as 2 seconds took a lot of clever software hacks that you’ll absolutely want to check out if you’ve ever considered building an embedded Linux device. You can’t just throw a stock Raspbian image on an SD card and hope for the best. [mitxela] used buildroot to craft a custom Linux image containing only what was needed for the camera to operate, plus a bunch of esoteric tweaks that the Junior Penguin Wrangler would likely never consider. Like shaving a full second off of the boot time by disabling dumping kernel messages to the serial port during startup.

[mitxela] brought his camera to show off at the recent Hackaday London meetup, but it was far from the first time we’ve come across his handiwork. From his servo-powered music box earlier this year to his penchant for tiny MIDI devices, he’s consistently impressed our cold robot hearts.

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