Fundamentals of Fingerprint Scanning

Like most (if not all) Hackaday readers, I like to know how the technology I use works. I’m always amazed, for example, how many otherwise smart people have no idea how the cellphone network works other than “it’s a radio.” So now that I have two phones with fingerprint scanners on them, I decided I needed to know more about what’s going on in there.

Sure, I assumed the sensor was capacitive (but maybe not, I found out). Plus we all know some super glue, scotch tape, and gummy bears are all you need to fake one out. However, that’s been known for about 15 years and we are still seeing phones and other devices rolling out with the same scanners. So for now, put aside the debate about whether we should be using fingerprint scanners. Let’s talk about how those sensors work.

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Friday Hack Chat: The Hackaday Prize

Did you know Hackaday is hosting a fantastic contest to build hardware and software? It’s true! The Hackaday Prize will award hundreds of thousands of dollars to Hackaday community members for building the coolest hardware designed to make a difference in the world.

The Hackaday Prize has many ways to enter, focusing on several themes throughout this year. We’ll be discussing that and opening the floor to questions. Tomorrow, Friday, April 28, at noon, Pacific time, we’re hosting a Hack Chat for the Hackaday Prize over on Hackaday.io.

Our guest host for this chat is [Alberto], creator of the project that won last year’s Hackaday Prize. He’ll be in the Hack Chat telling everyone what he learned from last year’s Hackaday Prize. If we’re lucky, he might even tell us something about what building his project out in the Supply Frame Design Lab is like. It’s all very cool, and it’s going down tomorrow at noon, PDT.

Here’s How To Take Part:

join-hack-chatOur Hack Chats are live community events on the Hackaday.io Hack Chat group messaging.

Log into Hackaday.io, visit that page, and look for the ‘Join this Project’ Button. Once you’re part of the project, the button will change to ‘Team Messaging’, which takes you directly to the Hack Chat.

You don’t have to wait until tomorrow; join whenever you want and you can see what the community is talking about.

And Tindie, Too!

Next Tuesday, we’re going to have another chat geared toward sellers on Tindie, the online marketplace where anyone can buy or sell DIY hardware.

This time around, we’re talking about Kickstarter. We roped [Zach Dunham] into this one. He’s the Design & Technology Outreach Lead at Kickstarter, and by every measure a really cool guy.

[Zach] will discuss the ins and outs of turning a hardware project into a Kickstarter campaign. Surprisingly, there’s a significant overlap between Tindie sellers and Kickstarter — some sellers test their ideas on Tindie and build up to doing a crowd funding campaign. Others complete a campaign and then come over to Tindie to sell excess inventory or second runs. Either way, there’s a great opportunity for market verification or simply getting your gear into the hands of those who want to use it.

If you want to get in on the Kickstarter chat action, head on over to the Tindie Dog Park. Request to join the project and show up in the chat sometime before 1pm Pacific on Tuesday, May 2.

Ask Hackaday: What About the Diffusers?

Blinky LED projects: we just can’t get enough of them. But anyone who’s stared a WS2812 straight in the face knows that the secret sauce that takes a good LED project and makes it great is the diffuser. Without a diffuser, colors don’t blend and LEDs are just tiny, blinding points of light. The ideal diffuser scrambles the photons around and spreads them out between LED and your eye, so that you can’t tell exactly where they originated.

We’re going to try to pay the diffuser its due, and hopefully you’ll get some inspiration for your next project from scrolling through what we found. But this is an “Ask Hacakday”, so here’s the question up front: what awesome LED diffusion tricks are we missing, what’s your favorite, and why?

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Life on Contract: Hacking your Taxes

You’re a contractor and people are paying you to work in your pajamas. It’s a life of luxury, but when tax time comes, you are in a world of hurt and you wonder why you even do it. Taxes are tricky, but there are some tools you can use to make it less painful on your pocketbook. With planning and diligence, you can significantly increase the amount of money that stays in your bank account. Continue reading “Life on Contract: Hacking your Taxes”

Hackaday Links: April 23, 2017

‘Member StarCraft? Ooooh, I ‘member StarCraft. The original game and the Brood War expansion are now free. A new patch fixes most of the problems of getting a 20-year-old game working and vastly improves playing over LAN (‘member when you could play video games over a LAN?) And you thought you were going to have free time this week.

About a year ago, [Mark Chepurny] built a dust boot for his Shapeoko CNC router. The SuckIt (not the best possible name, by the way) is an easy, simple way to add dust collection to an X-Carve or Shapeoko 2. The folks at Inventables reached out to [Mark] and made a few improvements. Now, the renamed X-Carve Dust Control System. It’s a proper vacuum attachment for the X-Carve with grounding and a neat brush shoe.

I don’t know if this is a joke or not. It’s certainly possible, but I seriously doubt anyone would have the patience to turn PowerPoint into a Turing Machine. That’s what [Tom Wildenhain] did for a lightning talk at SIGBOVIK 2017 at CMU. There’s a paper (PDF), and the actual PowerPoint / Turing Machine file is available.

System76 builds computers. Their focus is on computers that run Linux well, and they’ve garnered a following in the Open Source world. System76 is moving manufacturing in-house. Previously, they’ve outsourced their design and hardware work to outside companies. They’re going to work on desktops first (laptops are much harder and will come later), but with any luck, we’ll see a good, serviceable, Open laptop in a few year’s time.

Remember last week when a company tried to trademark the word ‘makerspace’? That company quickly came to their senses after some feedback from the community. That’s not all, because they also had a trademark application for the word ‘FabLab’. No worries, because this was also sorted out in short order.

Ask Hackaday: Why Did Modular Smart Phones Fail?

Remember all the talk about modular smart phones? They sounded amazing! instead of upgrading your phone you would just upgrade the parts a bit like a computer but more simplistic. Well it seems modular phones are dead (video, embedded below) even after a lot of major phone manufacturers were jumping on the bandwagon. Even Google got on-board with Google Ara which was subsequently cancelled. LG released the G5 but it didn’t fare too well. The Moto Z from Motorola seemed to suffer from the same lack of interest. The buzz was there when the concept of these modular phones was announced, and people were genuinely exited about the possibilities. What went wrong?

For a start people expect their phones to have everything on board already, whether it be cameras, GPS, WiFi, high-capacity batteries or high-resolution screens. Consumers expect these things to come as standard. Why would they go out and buy a module when other phones on the market already have these things?

Sure you could get some weird and wonderful modules like extra loud speakers or perhaps a projector, but the demand for these items was small. And because these extras are already available as separate accessories not locked down to one device, it was a non starter from the beginning.

When we did our user studies. What we found is that most users don’t care about modularizing the core functions. They expect them all to be there, to always work and to be consistent. — Lead engineer Project Ara

The hackability of these phones would have been interesting to say the least, had they come to the mainstream. It just seems the public want thin sleek aluminum phones that they treat more as a status symbol than anything else. Modular phones have to be more bulky to accommodate the power/data rails and magnets for the modules, so they’ll lose out in pocketability. Still, we hope the idea is revisited in the future and not left on the scrap-heap of obsolescence.

Would you buy a modular smart phone? Even if it is bigger or more expensive? Is that really why they failed?
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Pi Network Attenuators: Impedance Matching For The Strong Of Signal

If you catch a grizzled old radio amateur propping up the bar in the small hours, you will probably receive the gravelly-voiced Wisdom of the Ancients on impedance matching, antenna tuners, and LC networks. Impedance at RF, you will learn, is a Dark Art, for which you need a lifetime of experience to master. And presumably a taste for bourbon and branch water, to preserve the noir aesthetic.

It’s not strictly true, of course, but it is the case that impedance matching at RF with an LC network can be something of a pain. You will calculate and simulate, but you will always find a host of other environmental factors getting in the way when it comes down to achieving a match. Much tweaking of values ensues, and probably a bit of estimating just how bad a particular voltage standing wave ratio (VSWR) can be for your circuit.

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