Listening to the Sounds of the Earth

A geophone is a specially built microphone for listening to the Earth. [JTAdams] found them at a reasonable price so bought some to play with. A geophone is used to detect vibrations from earthquakes, explosions, rumbling trucks, and vibroseis vehicles. To be useful it needs an amplifier and a recording device to capture the signals.


[JTAdams] used a standard amplifier design for an LT1677 op-amp, fed the signal to an MCP3008 A/D converter, and read the output using a Raspberry Pi. A Python script records the data to a CSV file for processing. The Pi worked well because the entire setup needs to be portable to take into the field. Another Python script plots the data which is made available from a web page. A neat simple way of presenting the raw data. [JTAdams] promises more information in the future on post-processing the data. You don’t need a geophone to detect seismic waves if you build your own, but a real ‘phone will be more rugged.

Oh, what’s a vibroseis? It’s a truck with a big flat plate underneath it. The plate is hydraulically lowered to the ground until the weight of the truck is on it. The truck then causes the plate to vibrate, usually sweeping from around 10 hz to 100 hz. This infrasound pass through the ground until it is reflected back by underlying rock layers. A long string of geophones, think 1,000s of feet, detects the waves, which are recorded. In practice, many trucks are used to generate a synchronized signal of sufficient strength. Or, you can set off an explosion which is the technique used in water. Typically the information is used for oil and gas exploration.  A video of one of the trucks in action after the break.

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Conjuring Capacitive Touch Sensors from Paper and Aluminum Foil

Stumbling around YouTube, we found what has to be the lowest-tech method of producing a touchpad to make a capacitive touch keyboard, and we just had to share it with you. If you’re afraid of spoilers, skip down to the video below the break now.

[James Eckert] got his hands on a Freescale MPR121 capacitive touch sensor. The chip in question speaks I2C and senses up to twelve simultaneous capacitive sense electrodes; break-out boards are available in all of the usual places. It’s a sweet little part.

So [James] had to make a twelve-key capacitive keyboard on the quick. He printed out a key template on paper — something that he does often in his woodwork — and spray-glued aluminum foil on the back side. The video doesn’t say how many hours he spent with the razor blade tracing it all out, but the result is a paper, foil, and packing tape keyboard that seems to work just fine.

A pin-header was affixed to the foil with conductive paint and more tape. If you’ve ever tried soldering directly to aluminum foil, you’d know why. (And if you’ve got any other good tips for connecting electrically to aluminum foil, we’d love to hear them.)

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Building Custom Integrated Circuits

The first integrated circuits weren’t tiny flecks of silicon mounted to metal carriers and embedded in epoxy or ceramic. The first integrated circuits, albeit a looser definition of such, were just a few transistors, resistors, and diodes mashed together in the same package. With this in mind, [Rupert] created his own custom IC. It’s an IR receiver transmitter constructed out of a transistor, resistor, and an LED.

The attentive reader should be asking, “wait, can’t you just buy an IR receiver transmitter?” Yes, yes you can. But that’s not a hack™, and would otherwise be very uninteresting.

[Rupert]’s IC is just three parts, a 2n2222 transistor, a 220Ω resistor and an IR LED. With a good bit of deadbug soldering, these three parts were melded into something that resembled, and had the same pinout of, a Vishay TSOP4838 IR receiver. The epoxy used to encapsulate this integrated circuit is a standard 2-part epoxy and laser printer toner. Once everything is mixed up into a gooey slurry, it’s dripped over the IC producing a blob of an integrated circuit. It’s functionally identical to the standard commercial version, and looks good enough for a really cool project [Rupert]’s been working on.

Thanks [foehammer] for the tip.

An Introduction to Casting With Nuka Cola

There’s less than a month until the next Star Wars is released, and consequently a few weeks until amateur propmakers and cosplayers go insane fabricating their own lightsabers with lightsaber cross guards and rolling robots. Until then, Fallout is pretty cool and [Bill] is here to give us an introduction to prop making with one of the defining objects of this post-apocalyptic universe. He created a real life copy of a Nuka Cola bottle and created a great introduction to resin casting in the process.

As with all proper part making endeavours, this project began with getting reasonably accurate models of the object to be copied. In Fallout, we’re lucky enough to have a way to look at a specific object while zooming and spinning around it, giving [Bill] the basic shape. The size was rather easy as well: all bottlecaps are the same size, so [Bill] just scaled the model to that.

With the model created and the part printed out, assembled, and finished, it was time to create the mold. [Bill] used a two-part silicone mold for the basic shape. The actual casting was done by rolling around a little resin on the inside of the mold. There’s no need for a solid, bottle-shaped block of resin; bottles are hollow anyway.

There are a few neat tricks [Bill] has up his sleeve, including coating the inside of the mold with aluminum powder and using a vinyl cutter to get the labels and logos exactly right. The finished product turns out great, perfect for leaving in the Wasteland for 200 years until the Sole Survivor stumbles upon it.

Video below.

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Basic Toolkit for the Basement Biohacker

Laying hands on the supplies for most hacks we cover is getting easier by the day. A few pecks at the keyboard and half a dozen boards or chips are on an ePacket from China to your doorstep for next to nothing. But if hacking life is what you’re into, you’ll spend a lot of time and money gathering the necessary instrumentation. Unless you roll your own mini genetic engineering lab from scratch, that is.

arduino-based-biolab-data-logger-thumbTaking the form of an Arduino mega-shield that supports a pH meter, a spectrophotometer, and a PID-controlled hot plate, [M. Bindhammer]’s design has a nice cross-section of the instruments needed to start biohacking in your basement. Since the shield piggybacks on an Arduino, all the data can be logged, and decisions can be made based on the data as it is collected. One example is changing the temperature of the hot plate when a certain pH is reached. Not having to babysit your experiments could be a huge boon to the basement biohacker.

Biohacking is poised to be the next big thing in the hacking movement, and [M. Bindhammer]’s design is far from the only player in the space. From incubators to peristaltic pumps to complete labs in a box, the tools to tweak life are starting to reach critical mass. We can’t wait to see where these tools lead.

Metalab Bypasses IR Remote with Audio Circuit

Infra-red (IR) remotes are great, unless you’re in a hackerspace that’s full of crazy blinking lights and random IR emissions of all kinds. Then, they’re just unreliable. Some smart folks at Metalab in Vienna, Austria cut out the IR middle-man with a couple transistors and some audio software. They call the project HDMI Whisperer, and it’s a cute hack.

Metalab’s AV system has a web-frontend so that nobody ever has to stand up unless they want to. They bought an incredibly cheap 5-to-1 HDMI Switch to switch between displaying multiple video streams. But how to connect the switch to the Raspberry Pi server?

Fortunately, the particular switch has a remote-mounted IR receiver that connects to the main unit through a stereo audio jack. Plugging this sensor into a laptop and running Audacity while pressing the buttons on the remote got them audio files that play the remote’s codes. Simply playing these back out of the Raspberry Pi’s audio out and into the switch’s IR input through a tiny transistor circuit does the trick. Now they have a networked five-way HDMI switch for $10.

Given the low data rates of most IR remotes, we could imagine using the same trick for devices that have built-in IR receivers as well. Simply clip out the IR receiver and solder in a couple wires and then inject your “audio” signal directly.

But IR hacks are loads of fun. We’ve seen a bunch here, from the classic camera shutter-release hack to a more general tutorials on cloning IR signals with Arduinos.

Thanks [overflo] for the tip!

Byte Magazine Nostalgia Photo

Those of us who remember when microprocessors were young also recall the magazines of the era. Readers bought the magazine for content but the covers attracted attention on the newsstand. In the late 70s until the early 90s the competition was fierce, so great covers were mandatory. The covers of Byte magazine created by [Robert Tinney] were detailed, colorful, and always interesting.


[Bob Alexander] of Galactic Studios recreated one of those hand drawn covers using photographic techniques. The cover shows a steam engine, tender and caboose rolling along the traces on a PC board amidst a landscape populated by resistors, capacitors, and integrated circuits. The photographic clone recreates that image using all real components, including an HO train. The circuit, unfortunately, isn’t of a working device.

Creating this work followed all the normal hacking steps for a PC board: a mockup of the layout, designing the board, and ordering it from China. Component procurement was sometimes a hassle since some are no longer in production. The components that weren’t found on EBay were hacked.

The only image manipulation involved the HO train. It was much larger than the PC board so could not be put in place for the photo. Images of the PC board and the train were merged using software. Also added were smoke rings puffing out of the locomotive’s smokestack.

The photo is a worthy recreation of [Tinney’s] original.

For more trainy goodness, check out our own Brian Benchoff’s tour of the Siemens Model Train Club.  Or for further photo-realistic modelling, have a look at this insanely detailed Ford pickup model.