A Noob’s Guide to McMaster-Carr

For the penny-pinching basement hacker, McMaster-Carr seems like a weird go-to resource for hardware. For one, they’re primarily a B2B company; and, for two, their prices aren’t cheap. Yet their name is ubiquitous among the hacker community. Why? Despite the price, something makes them too useful to ignore by everyday DIY enthusiasts. Those of us who’ve already been enlightened by the McMaster-Carr can design wonders with a vocabulary of parts just one day away at the click of a button.

Today, this article is for those of us who have yet to receive that enlightenment. When used wisely, this source of mechanical everything brings us a world of fast parts at our fingertips. When used poorly, we find nothing but overpriced stock components in oversized shipping boxes.

Since we, the McMaster-Carr sages, are forever doomed to stuff our desk drawers with those characteristic yellow baggies till the end of time, we thought we’d give an intro to the noobs that are just beginning to flex their muscles with this almighty resource. Grab another cup of coffee as we take you on a tour of the good and good-grievances of McMaster-Carr.

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Get Inside a TCXO Clock Chip

[Pete] wondered how real-time clock modules could be selling on eBay for $1.50 when the main component, the Maxim DS3231 RTC/TCXO chip, cost him more like $4 apiece. Could the cheap modules contain counterfeit chips?

Well, sure they could. But in this case, they didn’t, and [Pete] has the die shots to prove it. He started off by clipping the SOIC leads rather than desoldering — he’s not going to be reusing this chip after he’s cut it in half. Next was a stage of embrittling the case by heating it up with a lighter and dunking it in water. Then he went at it with sandpaper.

It’s cool. You can see the watch crystal inside, and all of the circuitry. The DS3231 includes a TCXO — temperature-corrected crystal oscillator — and it seems to have a bank of capacitors that it connects and disconnects depending on the chip’s temperature to keep the oscillator running at the right speed. [Pete] used one in an offline situation, and it only lost sixteen seconds over a year, so we’d say that they work fine.

If you’d like to know more about how crystals are used to keep time, check out [Jenny]’s excellent article. And if sixteen second per year is way too much for you, tune up your rubidium standard and welcome to the world of the time nuts.

Pogo Pin Serial Adapter Thing

A few weeks ago, I was working on a small project of mine, and I faced a rather large problem. I had to program nearly five hundred badges in a week. I needed a small programming adapter that would allow me to stab a few pads on a badge with six pogo pins, press a button, and move onto the next badge.

While not true for all things in life, sometimes you need to trade quality for expediency. This is how I built a terrible but completely functional USB to serial adapter to program hundreds of badges in just a few hours.

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Nuts and Bolts: Keeping it Tight

It’s not much of a stretch to say that without nuts and bolts, the world would fall apart. Bolted connections are everywhere, from the frame of your DIY 3D printer to the lug nuts holding the wheels on your car. Though the penalty for failure is certainly higher in the latter than in the former, self-loosening of nuts and bolts is rarely a good thing. Engineers have come up with dozens of ways to make sure the world doesn’t fall apart, and some work better than others. Let’s explore a few of these methods and find out what works, what doesn’t work, and in the process maybe we’ll learn a little about how these fascinating fasteners work.

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PogoPlug Hacking: A Step by Step Guide to Owning The Device

[Films By Kris Hardware] has started quite an interesting YouTube series on hacking and owning a PogoPlug Mobile v4. While this has been done many times in the past, he gives a great step by step tutorial. The series so far is quite impressive, going into great detail on how to gain root access to the device through serial a serial connection.

PogoPlugs are remote-access devices sporting ARM processor running at 800 MHz, which is supported by the Linux Kernel.  The version in question (PogoPlug Mobile v4) have been re-purposed in the past for things like an inexpensive PBX, an OpenWrt router and even a squeezebox replacement. Even if you don’t have a PogoPlug, this could be a great introduction to hacking any Linux-based consumer device.

So far, we’re at part three of what will be an eight-part series, so there’s going to be more to learn if you follow along. His videos have already covered how to connect via a serial port to the device, how to send commands, set the device up, and stop it calling home. This will enable the budding hacker to make the PogoPlug do their bidding. In this age of the cheap single-board Linux computer, hacking this type of device may be going out of style, but the skills you learn here probably won’t any time soon.

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Open Source Firmware For A Cheap Programmable Power Supply

A few months ago, someone clued us in on a neat little programmable power supply from the usual Chinese retailers. The DPS5005 is a programmable power supply that takes power from a big AC to DC wall wart and turns it into a tiny bench-top power supply. You can pick one of these things up for about thirty bucks, so if you already have a sufficiently large AC to DC converter you can build a nice 250 Watt power supply on the cheap.

[Johan] picked up one of these tiny programmable power supplies. His overall impression was positive, but like so many cheap products on AliExpress, there wasn’t a whole lot of polish to the interface. Additionally, the DPS5005 lacked the ability to be controlled over a serial port or WiFi.

This programmable power supply is built around an STM32, with the programming pads exposed and labeled on the PCB. The changes [Johan] wanted to make were all in software, leading him to develop OpenDPS, a firmware replacement for the DPS5005. Continue reading “Open Source Firmware For A Cheap Programmable Power Supply”

33C3: Hunz Deconstructs the Amazon Dash Button

The Amazon Dash button is now in its second hardware revision, and in a talk at the 33rd Chaos Communications Congress, [Hunz] not only tears it apart and illuminates the differences with the first version, but he also manages to reverse engineer it enough to get his own code running. This opens up a whole raft of possibilities that go beyond the simple “intercept the IP traffic” style hacks that we’ve seen.

dash_block_diagramJust getting into the Dash is a bit of work, so buy two: one to cut apart and locate the parts that you have to avoid next time. Once you get in, everything is tiny! There are a lot of 0201 SMD parts. Hidden underneath a plastic blob (acetone!) is an Atmel ATSAMG55, a 120 MHz ARM Cortex-M4 with FPU, and a beefy CPU all around. There is also a 2.4 GHz radio with a built-in IP stack that handles all the WiFi, with built-in TLS support. Other parts include a boost voltage converter, a BTLE chipset, an LED, a microphone, and some SPI flash.

The strangest part of the device is the sleep mode. The voltage regulator is turned on by user button press and held on using a GPIO pin on the CPU. Once the microcontroller lets go of the power supply, all power is off until the button is pressed again. It’s hard to use any less power when sleeping. Even so, the microcontroller monitors the battery voltage and presumably phones home when it gets low.
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