An Audio Based USB Oscilloscope and Signal Generator for $20

SoundScope

Are you interested in building a 20kHz 2-channel oscilloscope and a 2-channel signal generator for only $20 with minimal effort? Be sure to check out [Jan_Henrik's] Instructable that goes over how to build this awesome tool from a cheap USB audio card.

We have featured tons and tons of DIY oscilloscopes in the past, but this effort resulted in something very well put together while remaining very simple to understand and easy to build. You don’t even need to modify the USB audio card at all. One of the coolest parts of this build is that you can unplug your probe assembly from your USB audio card, and bring it wherever your hacking takes you. After the build, all you need is [Christian Zeitnitz's] Soundcard Oscilloscope program and you are good to go. One of the major downsides that is often overlooked when using an audio based oscilloscope, is that it is “AC coupled”. This means you cannot measure low-frequencies (including DC signals) using a sound card. Be sure to heed [Jan_Henrik's] advice and do not use your built in audio card as an oscilloscope. With no protection circuitry, it is a sure fire way to fry your computer.

What analog projects have you built around an audio interface? We have seen such an interface used for many different applications, including a few fun medical related hacks (be sure to keep safety your first priority). Write in and let us know!

The Electrostatic Theory of Metal Whiskers

wiskersThanks to that wonderful ROHS stuff the EU passed more than a decade ago, we should be seeing a few high-profile failures of electronic components due to tin whiskers. These tiny hair-like extrusions of metal found most commonly in lead-free solder have destroyed billion dollar satellites and shut down nuclear reactors, despite no one knowing exactly how these whiskers form. Now there’s a new theory of metal whisker formation (abstract, unless you have access to APS) that actually has predictive power. Here’s the free version of the paper

[V. G. Karpov] from the University of Toledo suggest these whiskers are formed by differences in charge induced by metallurgical anomalies – contamination, differences in the grain of the solder, and oxides. Because of the difference in charge, the whiskers are extruded, for lack of a better word, out from the surface of the solder.

The theory of whisker growth is generally consistent with observed rates of whisker growth and other properties. With this theory, it should even be possible to grow tin whiskers. Why anyone would want to do that other than, ‘because it’s cool’ is anyone’s guess, but there you go.

Running Minecraft On Two Routers

router

[CNLohr] is no stranger to running Minecraft on some weird hardware. Earlier, he built this Linux powered microscope slide… thing to toggle LEDs with redstone levers in Minecraft. Figuring if Minecraft could run on an AVR, he decided to try the same thing on a router, a TP-LINK TL-WR841N to be specific. Like the microscope slide running Linux, this proved to be an easy task. [CNLohr] had another router he could run Minecraft on, and this one could also punch wood. There really was only one thing for him to do.

Like the microscope slide and the wireless router, [CNLohr]‘s CNC router is now running a Minecraft server. The phrase, “because it’s there” comes to mind. When connected to the CNC server, the player controls a snow golem (a snowman with a jack ‘o lantern head) with a carrot. Wherever the snow golem goes, the tool head follows, allowing him to carve objects in the world, and on a sheet of MDF secured in the CNC machine.

It’s certainly an odd build, but [CNLohr] was able to carve out a pixeley, blocky Hackaday logo with the snow golem controlled CNC machine. Code here, video below.

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Internet Controlled LED Necktie Lights Up The Party

MIDI Controlled Necktie

Wearable devices are all the rage in certain circles — looking for a project of his own, [Hector Urtubia] decided to give it a shot with this six-LED necktie.

It used to be pretty hard to make an Internet connected device without spending all your time and effort on making the Internet connection possible — until the Pinoccio came along. It’s a tiny Arduino compatible board which has wireless Internet connectivity built right in. It even comes with a rechargeable battery. If you have experience with Arduino programming, this little guy is a cinch to get running.

The tie itself makes use of six NeoPixels, which are chainable, addressable and current regulating RGB LEDs, which means the entire chain of LEDs only requires 1 digital pin-out on the Pinoccio! [Hector] has even written a library that will extend the Pinoccio’s scripting environment so that the pixels can interact directly from the web or API.

To demonstrate the tie, he decided to hook it up to his MIDI keyboard — enjoy:

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Ancient TV Remote Becomes a CNC Pendant

DIY CNC Pendant

Needing a control pendant for his CNC machine, [Bob Davis] took to his scrap bin and started looking for parts. What he came up with is pretty cool — that’s a rather old Zenith TV remote providing the enclosure!

When building a homemade CNC machine, many people overlook one of the most handy components — the control pendant. On a commercial machine, they can get pretty pricey — on a homemade machine, most people just use the computer to control it, but if you’ve used a pendant before you know how handy they are for manual operations!

So what should you do? Well, you could make a second dedicated keyboard for your CNC machine (arguably not much of a hack, but rather clever) — or you could build a pendant from scratch like [Bob] did. It’s pretty simple; he’s using a 555 timer, a few momentary toggle switches, an LED, and plans to add a potentiometer in the future for speed control. It’s all housed in the old TV remote, and seems to do the trick just fine — take a look in the following video:

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Connecting Inexpensive pH Probes with Ease

 

We’ve mentioned that it’s hard to find someone not selling or crowd funding something at Maker Faire. Despite the fact that [Ryan Edwards] is selling his boards, we still got the feeling that he’s a hacker who is selling just to make sure the idea he had is available for other hackers to use. He showed us his interface boards for inexpensive pH probes.

Since we’re always looking for more chemistry hacks to run, it was nice to hear [Ryan's] description on how these probes (which can be had for around $9 on eBay) actually work. It turns out it’s all about salt. When it comes to the electronics, the board provides a connector for the probe on one edge, and pins for voltage, ground, and I2C on another. Rig this up with your microcontroller of choice and you’ll be building your own automatic pool doser, fish tank minder, or one of a multitude of food-related hacks.

Head on over to Sparky’s Widgets to see a few other demo applications.

[Ken Shirriff] Explains The TL431

tl431

[Ken Shirriff] had to get down into a bit of semiconductor physics to give us an explanation of the TL431, which he calls “the most common chip you’ve never heard of”. [Ken] may well be right about the TL431. Even Texas Instruments can’t nail down a single name for it. Their page for the part calls it a “Adjustable Precision Shunt Regulator”, yet the datasheet is titled “Precision Programmable Reference”. You’d think they’d have figured this out by now, considering the TL431 was launched in 1978.

TL431’s can most often be found hiding in switching power supplies. The Apple II switcher had one, and many current ATX supplies have 3. Uninformed parts scroungers may miss them, as they often hide in TO-92 or SOT-23 packages. The TL431 is no transistor though. The TL431’s operation is actually pretty simple. When the voltage at the reference pin is above 2.5V, the output transistor conducts. When the reference voltage falls below 2.5V, the device stops conducting. In a power supply, this operation would help the control electronics maintain a stable output voltage.

The real subject of [Ken's] article is the layout of the TL431 on its silicon die.  Rather than bust out the fuming nitric acid himself, [Ken] uses some of [Zeptobars'] decapped chip images. Inside the TL431, [Ken] discovers that transistors aren’t made up of the three layer NPN or PNP sandwich we’ve come to know and love. In fact, the base isn’t even in the middle. Transistors, including the BJT’s used in the TL431, can be assembled in a nearly infinite number of ways.

[Ken] moves on to the resistors and capacitors of the TL431. The capacitors are formed two different ways, one as a reverse biased diode, and the other as a more traditional plate style capacitor. The resistors include fuses which can be blown to slightly increase the resistance values.

The takeaway from all this is that once you get down to the silicon level, it’s a whole new ball game. Chip layout may look a bit like PCB layout, but the rules are completely different. [Ken] mentions that in a future blog he’ll go into further detail on the operation of the TL431’s bandgap voltage reference. We’ll be watching for that one, [Ken]!

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