One Chip Does It All In This MacGuyver Synth

January 27, 2020 by Kristina Panos 33 Comments

When you think of simple synths, what components come to mind? All you really need to make one is an oscillator, an amplifier, and some kind of input such that you can play different notes. Our favorite go-to for churning out square waves is probably the 40106 IC, which has six inverting Schmitt triggers, and then usually a 386 to amplify the output.

But it’s possible to go even simpler than that, and school is in session with [Jule] giving the lesson. [Jule]’s little analog synth uses a single IC for both the oscillator and the amplifier — a TL072 op-amp. The rest is made of purely discrete components.

[Jule] says those momentary switches are sub-par, and will add a vibrato effect if properly wiggled while pressed. To us, the buttons looks pretty nice, and much easier to jam out with than the ones with 1/8″ diameter actuators. Plus, whenever you press multiple buttons, the additive resistance unlocks the synth’s inner R2D2 voice. We really see no downsides here.

By default, this is an eight-button synth tuned to C major. But there’s a surprise — you can plug different capacitors into a piece of header and change the octave on the fly. Check it out after the break.

Making pitch-correct frequencies requires weird resistor values, which we can usually satisfy with two resistors in series. But wait, what’s up with resistor values, anyway? And why do they have a color code?

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CRISPR Could Fry All Cancer Using Newly Found T-Cell

January 27, 2020 by Kristina Panos 36 Comments

One of the human body’s greatest features is its natural antivirus protection. If your immune system is working normally, it produces legions of T-cells that go around looking for abnormalities like cancer cells just to gang up and destroy them. They do this by grabbing on to little protein fragments called antigens that live on the surface of the bad cells and tattle on their whereabouts to the immune system. Once the T-cells have a stranglehold on these antigens, they can release toxins that destroy the bad cell, while minimizing collateral damage to healthy cells.

CAR T-cell therapy process via National Cancer Institute

This rather neat human trick doesn’t always work, however. Cancer cells sometimes mask themselves as healthy cells, or they otherwise thwart T-cell attacks by growing so many antigens on their surface that the T-cells have no place to grab onto.

Medical science has come up with a fairly new method of outfoxing these crafty cancer cells called CAR T-cell therapy. Basically, they withdraw blood from the patient, extract the T-cells, and replace the blood. The T-cells are sent off to a CRISPR lab, where they get injected with a modified, inactive virus that introduces a new gene which causes the T-cells to sprout a little hook on their surface.

This hook, which they’ve dubbed the chimeric antigen receptor (CAR), allows the T-cell to chemically see through the cancer cells’ various disguises and attack them. The lab multiplies these super soldiers and sends them back to the treatment facility, where they are injected into the patient’s front lines.

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CNC Etch-A-Sketch: Stop Motion Is Logical Next Step

January 26, 2020 by Kristina Panos 7 Comments

It happens to everyone. You get your hands on an Etch-A-Sketch for the first time, and armed with the knowledge of how it works, you’re sure you can draw things other than rectangles and staircases. And then you find out the awful truth: you are not as precise as you think you are, and if you’re [QuintBUILDS], the circles you try to draw look like lemons, potatoes, or microbes.

Okay, yes, this definitely isn’t the first CNC-ified Etch-A-Sketch we’ve seen, but it just might be the coolest one. It’s certainly the most kid-friendly, anyway.

Most importantly, you can still pick it up and shake it to clear the screen, a feature sorely lacking in many of the auto-sketchers we scratch about. And if you’re not fully satisfied by this hack, be sure to check out the stop-motion video after the break that turns this baby into a touch-screen video player for Flatlanders.

Turn it over and you’ll find a Raspberry Pi 3 and a CNC hat. The knobs are belt-driven from a pair of NEMA-17 size stepper motors that interface to the knobs with tight-fitting pulleys. Power comes from four 18650s, and is metered by a battery management board that provides both overcharge and drain protection. At some point in the future, [QuintBUILDS] plans to move to a battery pack, because the cell holder is electrically unstable.

We love the welded frame and acrylic enclosure because they make the thing sturdy and portable. Also, we’re suckers for see-through enclosures. They’re clearly superior if you want to do what [QuintBUILDS] did and take it to an elementary school science fair to show the kids just how cool science can be if you stick with it.

If you don’t think motorized Etch-A-Sketches can be useful, maybe you just haven’t seen this clock build yet.

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Feel The Force With A Pocket Magnetometer

January 24, 2020 by Kristina Panos 12 Comments

With the rise of affordable 3D printers, we just don’t see the projects in Tic Tac boxes that we used to. That’s kind of a shame. Not only are you upcycling existing plastic when you use one, they’re decently sized component vessels for pocket builds such as [rgco]’s portable magnetometer, especially if you can get the 100-count box. Best of all, they’re see-through!

Sure, you could get a magnetometer app for your phone to test out the strength of your Buckyballs, but this is more fun, and you can use it in more places. This build doesn’t take much — an Arduino Nano reads from a Hall effect sensor and outputs the magnetic flux density in militeslas (mT) on an OLED. Fortifying the sensor by mounting it inside the body of an old (also see-through!) ballpoint pen body is a nice touch.

In order to calibrate it, [rgco] made a solenoid by wrapping a length of PVC with magnet wire. The code for this very portable and low-cost magnetometer measures the magnetic field 2000 times in under three-tenths of a second, and outputs both the mean and the standard deviation of these measurements.

Magnetometers can ID all kinds of things from submarines to Suburbans. Here’s an ESP8266 magnetometer that opens a driveway gate when it detects the car.

Pi 4 Emulator In A Durable, Dumpstered Cabinet

January 23, 2020 by Kristina Panos 9 Comments

We must be looking in the wrong Dumpsters, because we never find anything as cool as [Queen_Combat] did. It’s one of those Kidzspace kid-proof waiting room game systems, complete with the original TV and an XBOX 360 that hasn’t been updated since 2009. When life hands you a sturdy game console box, it’s almost your duty to turn it into an all-in-one Raspberry Pi 4 emulation station.

[Queen_Combat] relocated the speakers from the top to the inside, just behind the vent holes on the sides, and printed a couple of mountable custom enclosures to hold them there. These are driven with a little 5W amplifier board, and everything is run from the XBOX’s power supply.

We particularly like the use of extenders in cigarette-lighter form factor, because we hadn’t seen those before. [Queen_Combat] printed a couple of adapters to make them fit nicely into the large holes on the front where the XBOX controllers were once attached — one has a volume knob, and the other has a USB3 port and a 3.5mm audio jack. [Queen_Combat] wanted to have HDMI audio out as well, so there’s an HDMI audio extractor in the mix, too, and another extender around back. Only thing missing is a paint job and some sweet vinyl graphics.

Yes, vinyl graphics would be sweet, but how? Not on the laser cutter, if that’s what you’re thinking. Don’t dismiss vinyl cutters out of hand, because they can do a whole lot more than that.

Via r/raspberry_pi

Lovebox Gives Infinite Treats Sweeter Than Chocolate

January 22, 2020 by Kristina Panos 8 Comments

Want to make a special Valentine’s Day gift that keeps on giving well past the holiday? We do too, especially if it’s something as cute as [Marcel Stör]’s Lovebox. This is a relatively simple build, but it’s the kind that lets you make someone’s day over and over again.

The sender composes their love note in a secret GitHub gist, either as a text message or a binary image, and updates the gist. Whenever the Wemos D1 mini inside the box receives a new message, a micro servo slowly wiggles the hearts up and down to notify the recipient.

Once they remove the lid to read it, a light-dependent resistor senses the flood of light on its face and tells the servo it can stop wiggling. We think it’s neat that the heart nudges upwardly at the box lid a bit as it moves, because it increases the cuteness factor.

Everybody loves to hear from that special someone throughout the day. The idea of sending an intimate message remotely is quite romantic, and there’s something thrilling and urgent about a physical notification. Show the break button a little love, and you’ll see a truffle-sized demo featuring both an incoming image and a text message.

[Marcel] was happy to ply his woodworking skills rather than use a laser cutter. If you have neither of these, hit up a craft store or two and you’ll find unfinished wooden boxes and pre-cut hearts galore. Or, you could just say it with copper.

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HDD-Driven Chime Clock Is Quite Striking

January 21, 2020 by Kristina Panos 20 Comments

It seems that the more hectic life gets, the harder it is to consciously slow down and enjoy the experience. There’s always another bill to worry about, and a new deadline around the corner. The last thing we need are ultra-precise digital clocks everywhere we look. When it’s time to relax, there’s more than enough room for a passive type of clock that gives the time on time’s terms.

[Scoops]’ beautiful chime-only clock seems perfect for its location — an intimate event space inside an old house in Taiwan. Having only a vague sense of passing time helps us relax responsibly at social events. There’s no need to pull out your phone or glance at your watch when notifications about the passage of time softly permeate the air.

Here’s how it works: a NodeMCU controls four hard drive actuators through a ULN2003. The actuators each have a small extension and a clapper fitted on the end, which strikes the aluminium tubes that make up the chimes. There’s a web interface where [Scoops] can set the chimes to sound as frequently or infrequently as desired, or schedule a quiet period during the overnight hours. In emergencies, the clock can also be muted directly with the push of a button.

Take a little time to check out the short videos after the break, because this thing does a mean Westminster Chimes. But don’t stay too long, because time is running out! You have until Friday, January 24th to enter our Tell Time Contest over on IO.

Time can be relaxing or suffocating, depending on the way you look at it. If it’s visual relaxation you need, watch this bubble clock and float away from reality for a while.

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