Reworking MT3608 Boost Converters For Lower Idle Current Draw

The MT3608 is a popular boost converter, able to easily step up DC voltages in useful ranges, at an incredibly low cost. Modules can be sourced from eBay for less than $2, built on a PCB, ready to go. One drawback of these modules, particularly when working with batteries, is the idle current draw, on the order of 1 to 1.5mA. Fear not, however — there is a workaround, courtesy of [Aka Kasyan]. (Video, embedded below.)

The trick is to modify the behavior of the converter when no load is connected. The enable pin of the boost converter is held low through a pull-down resistor, keeping the boost converter switched off. In this state, the output voltage is equal to the input voltage. A current sense resistor is then installed in the output path. When a load is connected, this causes a voltage drop across the current sense resistor. This is then used to switch a transistor, which then connects the enable pin to the positive rail, switching the converter on, leading to the full boosted output voltage being reached.

[Aya] reports that this drastically cuts the idle current draw, which is particularly useful for battery powered projects. It’s important to note that the current sense resistor must be appropriately sized for the given load, however. If you’re a little hazy on the background, fear not — we’ve discussed the nature of boost converters before. Video after the break.

[Thanks to Baldpower for the tip!]
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Badland Brawler Lets Arduino Tackle Terrain

For an electronics person, building the mechanics of a robot — especially a robust robot — can be somewhat daunting. [Jithin] started with an off-the-shelf 4 wheel drive chassis to build an off-road Arduino robot he calls the Badland Brawler. The kit was a bit over $100, but as you can see in the video below, it is pretty substantial, with an enclosed frame and large mud tires.

The remaining parts include an Arduino, a battery, and a motor driver IC. The Arduino is one with WiFi (an MKR 1000, in fact) and there’s a phone app for controlling the robot.

Honestly, once you have the chassis taken care of, the rest is pretty easy. Of course, the phone app is a bit more effort, but you could replace it in a number of ways. Blynk, comes to mind, for example.

The motor drivers are easy to figure out. This would be a great platform for some sensors to allow for more autonomy. We liked how the frame had mount points for a lot of different boards and sensors and could hold everything, for the most part, inside. That’s probably a good idea for a robot which will be traversing rugged terrain.

If you do decide to roll your own app with Blynk, we’ve done it with a very different kind of robot. Four-wheel drive robots don’t have to be big, as we’ve seen in the past.

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Hackaday Links: January 27, 2019

Once again, Uber found a company to build their ‘air taxis’. This time it’s Boeing. While there are no details on the Boeing bird, I’m going to propose again that Uber buy the Santa Monica airport as a hub for their air taxi program; SMO is going to be shut down anyway, and this is the funniest reality that can come from the idea of an ‘air taxi’ program.

According to ancient astronaut theorists, one of the bigger problems with full-time tech YouTubers (think Dave and Fran here) is the insistence that YouTube suggests conspiracy theory videos as a related video. If you do a video teardown on Apollo flight hardware, you’re going to fall into the same category as people who believe the moon is hollow, people who believe the moon landing was faked, and recently, flat-earthers. This is a ‘bad move’ by YouTube because the Venn diagram of people who want to watch conspiracy videos and people who want to watch teardowns is two circles. It makes community engineering hard, and you get a lot of idiots on YouTube comments. YouTube is now changing the recommendation algorithm. There are other reasons YouTube is doing this, specifically relating to videos that aren’t about weird electronics, but we’re not going to talk about that here, thx.

This week was Winter NAMM, the National Association of… music, something something. That means you can go to Anaheim and check out all the musical instrument related stuff that will be released this year. Think of it as CES, only you don’t get the flu and want to murder everyone, and it’s about guitars and synths instead of Alexas duct taped to Roombas. Here’s what it was like last year, with the tl;dr being a wall of cabs, Euroracks everywhere, and the best way to get started in the industry is to buy some old trademarks, not by actually designing something new. Speaking of, here are some Kay reissues.

So, what’s cool at NAMM this year? Let’s do guitars first. Gibson’s 2019 lineup is not dumb, a reversal of the previous twenty years; There’s a Les Paul Standard with humbuckers or P90s, and there’s a TV Junior. Fender? There’s an acoustasonic Tele that was terrible the first time around, and it’s decidedly not terrible. The Electric XII is back, finally, and it’s even cooler than the Electric Six wait never mind it has a 1 11/16th nut. There is no Tele Plus with a Honda Goldwing emblem, but we make do with what we can. The pyramids are upside-downBuy a dookie pedal.

How about some synths?  Behringer is cranking out another clone, this time an Oberheim OB-Xa. Word on the street is that a 303 is on the horizon, but the vocoder is out now. The Odyssey exists, and the SH-101 clone comes with a handle so you can keytar it.  Guitars with Raspberry Pis? Could it be? Yes, Lucern Custom Instruments is collaborating with Tracktion to put a synth in a guitar. There’s a touchscreen BioTek 2 synth installed below the bridge. It’s like something [Matt Bellamy] would play, but it’s got a Raspberry Pi.

Elektron has a new samplerOh my god, the only way to make money in the instrument industry is to buy up trademarks. Well, trademarks and signature amps and guitars. Speaking of, where’s the signature Vangelis synths?

The news that will have the biggest impact a decade from now is the announcement that MIDI 2.0 is getting ready for release. New features include auto-config with DAWs, extended resolution, and expressiveness (to stop the Western hegemony on electronic music), and backward compatibility with MIDI 1.0.

This isn’t explicitly NAMM-related, but Eurorack is now a thing and [Jan] is always coming up with some interesting synths-on-a-chip. This time, it’s a drum machine in a Eurorack format. Is it based on anything? Not really, although it would go well in any Detroit acid track. Check out the video.

Air Knife Keeps GoPro Lens Clean In Messy Environments

Before the GoPro, shooting video of messy, fast-paced, or dangerous things was very different. There were commercial sports camera rigs and various industrial solutions, but the GoPro, with its waterproof housings and diminutive size, was the revolutionary, stick-it-anywhere camera. Despite this, the team at [tarkka] were having issues with the lens getting covered in coolant while shooting videos of their CNC machining projects. To solve this, they created an air knife to clean the lens.

The air knife consists of a wide, flat nozzle that is designed to blow fluid off of the lens. It’s a tidy 3D printed design, which wraps around the GoPro housing. Felt pads are used to give a snug fit, so the device simply slides into place and stays there. The device is fed from a hand-operated nozzle at present, though the team notes that this could be changed to a more permanent connection.

In testing, the device has performed well, even when under a constant barrage of coolant spray. This should make shooting CNC videos much easier for the team, who were formerly required to manually wipe the camera down several times during a shoot. The build was actually inspired by an earlier build by [Edge Precision], which used machined aluminum parts to create a similar tool.

The GoPro remains a popular camera wherever a small and rugged device is required. Consider mounting one to a toy car for a weekend’s worth of fun. Video after the break.

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Quartet Of SMD Resistors Used To Sense Z-Axis Height

Here’s a neat trick for your next 3D-printer build or retrofit: a Z-axis sensor using a DIY strain gauge made from SMD resistors. We’re betting it could have plenty of other applications, too.

Conventional load cells, at least the ones you can pick up cheaply from the usual sources or harvest from old kitchen or bathroom scales, are usually way too big to be used on the extruder of a 3D-printer. [IvDm] wanted to build a touch sensor for his Hybercube printer, so he built his own load cell to do it. It consists of four 1000 ohm SMD resistors in the big 2512 device size. He mounted them to an X-shaped PCB and wired them in the classic Wheatstone bridge configuration, with two resistors on one side of the board and two on the other.

The extruder mounts into a hole in the center of the board and floats on it. Through an HX711 load cell driver chip, the bridge senses the slight flex of the board when the extruder bottoms out on the bed, and an ATtiny85 pulls a limit switch input to ground. [IvDm] even did some repeatability testing with this sensor and it turned out to be surprisingly consistent. The first minute or so of the video below shows it in action on the Hypercube.

We found the use of SMD resistors as strain gauges pretty clever here, but there’s plenty to do with off-the-shelf load cells: measuring how much filament is left on a roll, checking the thrust of a model rocket engine, or even figuring out if you’re peeing correctly.

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Open Source Fader Bank Modulates Our Hearts

Here at Hackaday, we love knobs and buttons. So what could be better than one button? How about 16! No deep philosophy about the true nature of Making here; [infovore], [tehn], and [shellfritsch] put together a very slick, very adaptable bank of 16 analog faders for controlling music synthesis. If you don’t recognize those names it might help to mention that [tehn] is one of the folks behind monome, a company built on their iconic grid controller. Monome now produces a variety of lovingly crafted music creation tools.

Over the years we’ve written about some of the many clones and DIY versions of the monome grid controller, so it’s exciting to see an open source hardware release by the creators themselves!

The unambiguously named 16n follows in the footsteps of the monome grid in the sense that it’s not really for something specific. The grid is a musical instrument insofar as it can be connected to a computer (or a modular synth, etc) and used as a control input for another tool that creates sound. Likewise, the 16n is designed to be easily integrated into a music creation workflow. It can speak a variety of interfaces, like purely analog control voltage (it has one jack per fader), or i2c to connect to certain other monome devices like Ansible and Teletype. Under the hood, the 16n is actually a Teensy, so it’s fluent in MIDI over USB and nearly anything else you can imagine.

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Casting Concrete With 3D Printed Molds

[Thomas Sanladerer] wanted to create some molds using 3D printing for concrete and plaster. He used a delta printer with flexible filament and documented his process in the video below.

If you’ve printed with flexible filaments before, you know you need an extruder that has a contained path. [Tom] borrowed a printer, but it didn’t have that kind of set up. The first step was to swap extruders with another printer.

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