A Class D Amp Made From Scrap

February 18, 2015 by Brian Benchoff 26 Comments

[Boolean90] needed an amplifier for a subwoofer, and had a lot of parts sitting around in a scrap bin. His project, a Class D sub amp made out of scrap, is a great example of what you can build with the right know-how and a very large pile of junk.

With digital logic and PWM chips, a Class D amp is one of the simpler ways to get a lot of amplification easily in an efficient package. It’s really not that complicated; an audio signal is turned into a PWM’d square wave, this is sent out to a Mosfet bridge, and finally out to the speaker.

Most Class D amps have a switching frequency of hundreds of kilohertz to the Megahertz range, but since this is an amplifier for a subwoofer that has a cutoff frequency of about 1kHz, the switching frequency doesn’t need to be quite as fast. [Boolean] is using a 50kHz carrier frequency; it’s more than high enough to recreate low frequencies.

With the completed project, [Boolean] has an extremely loud amplifier that has around 75-150W of output power. The subwoofer is only rated for 200W, but with the volume [Boolean] is getting, this isn’t an amp he’ll be rebuilding anytime soon.

How To Zip, Stick, And Screw Stuff Together

February 18, 2015 by George Graves 51 Comments

One of the first problems every new hacker/maker must solve is this: What’s the best way to attach part “A” to part “B”. We all have our go-to solutions. Hot glue, duck tape ( “duct tape” if you prefer) or maybe even zip ties. Super glue, epoxy, and if we’re feeling extra MacGyver-ish then it’s time for some bubble gum. For some Hackaday readers, this stuff will seem like old hat, but for a beginner it can be a source of much frustration. Even well versed hackers might pick up a few handy tips and tricks presented in this video after the break.

In part one of this series, [Ben Krasnow] shows us the proper use of just a few of the tools and techniques he uses in his shop. [Ben] starts out with a zip-tie tool which he loves in part because of a tension setting that ensures it’s tight but not overly. He moves on to advice for adhesive-vs-material and some tips on using threaded fasteners in several different circumstances. He also included a list of the parts and tools he uses so you don’t have to go hunting them down.

[Ben] is no stranger to us here at Hackaday. He does some epic science video. You can subscribe to his channel or follow his blog if you enjoy what you see.

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Custom Double-Din Mount For Nexus 7 Carputer

February 18, 2015 by Rick Osgood 23 Comments

Many new vehicles come with computers built into the dashboard. They can be very handy with features like GPS navigation, Bluetooth connectivity, and more. Installing a computer into an older car can sometimes be an expensive process, but [Florian] found a way to do it somewhat inexpensively using a Nexus 7 tablet.

The size of the Nexus 7 is roughly the same as a standard vehicle double-din stereo slot. It’s not perfect, but pretty close. [Florian] began by building a proof of concept mounting bracket. This model was built from sections of MDF hot glued and taped together. Plastic double-din mounting brackets were attached the sides of this new rig, allowing it to be installed into the dashboard.

Once [Florian] knew that the mounting bracket was feasible, it was time to think about power. Most in-vehicle devices are powered from the cigarette lighter adapter. [Florian] went a different direction with this build. He started with a cigarette lighter to USB power adapter, but he cut off the actual cigarette lighter plug. He ended up wiring this directly into the 12V line from the stereo’s wiring harness. This meant that the power cord could stay neatly tucked away inside of the dashboard and also leave the cigarette lighter unused.

[Florian] then wanted to replace the MDF frame with something stronger and nicer. He modeled up his idea in Solidworks to make sure the measurements would be perfect. Then the pieces were all laser cut at his local Techshop. Once assembled, the plastic mounting brackets were placed on the sides and the whole unit fit perfectly inside of the double-din slot.

When it comes to features, this van now has it all. The USB hub allows for multiple USB devices to be plugged in, meaning that Nexus only has a single wire for both power and all of the peripherals. Among these peripherals are a USB audio interface, an SD card reader, and a backup camera. There is also a Bluetooth enabled OBD2 reader that can monitor and track the car’s vitals. If this project seems familiar to you, it’s probably because we’ve seen a remarkably similar project in the past.

Show Me The Data: Hackaday.io Year #01

February 18, 2015 by Aleksandar Bradic 57 Comments

Today marks exactly one year since we announced to the world the first product from our software lab – Hackaday.io. In what has been an incredibly exciting year for all of us, we evolved from a simple idea and a prototype to a truly massive community that’s making its mark on the world. Day after day, carefully listening to the invaluable feedback from our users, we have improved and moved forward, one line of code at the time.

We still have a long way to go, but we’ll pause for a second now and reflect on how far we’ve come. Then get right back to fixing bugs and developing new features.

It all started with a simple idea – building a better project hosting website. Though there are project and content websites galore out there, with new ones popping up every day, it all still felt too bland. We thought we could do better. After all, the medium is the message. The place where something lives sooner or later becomes a key part of its identity. So in order to prevent a dystopian future in which we’re all hosting our projects using the (fictional) Microsoft Maker Suite 2020 and simply don’t care, we started to work on providing an alternative.

We quickly realized that we had a much bigger mission on our hands. Sure, a better project hosting website would be nice, but what we felt we really needed was something [Brian Benchoff] has been talking about for quite some time – a “virtual hackerspace.” Not just a place where you can post your builds once you’re done (and hope someone sees it), but a living, breathing community: a place where you can start with an idea and get feedback as it develops, find collaborators, iterate, and ultimately end up building something way more amazing than you would have accomplished on your own.

This has been the aim of Hackaday for many years, but most of the collaboration was constrained to the limited space of post comment threads and biased by the editorial choice of articles and topics. With the introduction of Hackaday.io, we open up a space for anyone to unleash their creativity and expertise, and together, change the way people build things.

The Data

Unfortunately, making bold claims about how we’re out there changing the world is pretty much a commodity these days. As most Web startups can testify, it doesn’t take more than a simple landing page with nice photography and some uplifting message for any arbitrary claims to appear credible.

So instead of trying to convince you with words about how awesome the last year had been, we’ll just stick with the data.

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New Part Day: Time Of Flight Sensors

February 18, 2015 by Brian Benchoff 30 Comments

Every robotics project out there, it seems, needs a way to detect if it’s smashing into a wall repeatedly, acting like the brainless automaton it actually is. The Roomba has wall sensors, just about every robot kit has some way of detecting obstacles its running into, and for ‘wall-following robots’, detecting objects is all they do.

While the earliest of these robots used a piece of wire and a metal contact to act like a switch for these object detectors, ultrasonic sensors – the kind you can buy on eBay for a few bucks – have replaced this clever wire spring switch. Now there’s a new sensor for the same job – the VL6180 – and it measures the speed of light.

The sensors that are used for object and collision detection now use either ultrasonic or infrared light. They’re susceptible to noise, and if you’re doing anything automated, you really don’t want rogue measurements. A time of flight sensor clocks out photons and records how long it takes them to return at 299,792,458 meters per second. It’s less sensitive to noise, and if you can believe this SparkFun demo of this sensor, extremely accurate

This is not the first Time of Flight distance sensor on the market; earlier this week we saw a project use a sensor called the TeraRanger One. This sensor costs €150.00. The VL6180 sensor costs about $6 in quantity one from the usual suspects, and breakout boards with the proper level converters and regulators can be found for about $25. More expensive sensors have a greater range, naturally; the VL6180 is limited to somewhere between 10cm (on paper) and 25cm (in practice). But this is cheap, and it measures the time of flight of pulses of light. That’s just cool.

Unlock Your Demo Kindle Paperwhite

February 18, 2015 by Rick Osgood 26 Comments

If you’ve been holding off on upgrading your kindle, this project might inspire you to finally bite the bullet. [WarriorRocker] recently saved quite a few dollars on his Kindle upgrade by using a demo unit. Of course, it’s not as simple as just finding a demo unit and booting it up. There’s some hacking involved.

[WarriorRocker] found his Kindle Paperwhite demo unit on an online auction site for just $20. Kindles are great for reading but also make popular displays for your own projects. This used display model was much less expensive than a new unit, which makes sense considering it had probably received its share of abuse from the consumers of some retail store. The problem with a demo unit is that the firmware that comes with it is very limited, and can’t be used to sync up with your Amazon account. That’s where the hacking comes in.

The first step was to crack open the case and locate the serial port. [WarriorRocker] soldered a small three pin header to the pads to make it easier to work on his device as needed. He then connected the Kindle to his PC using a small serial to USB adapter. Pulling up the command prompt was as simple as running Putty and connecting to the correct COM port. If the wires are hooked up correctly, then it just takes a press of the enter key to pull up the login prompt.

The next step requires root access. The root password for each unit is related to the unit’s serial number. [WarriorRocker] obtained the serial number by rebooting the Kindle while the Serial connection was still open. The boot sequence will spit out the number. This number can then be entered in to an online tool to generate possible root passwords. The tool is available on [WarriorRocker’s] project page linked above.

Next, the Kindle needs to be rebooted into diagnostic mode. This is because root logins are not allowed while the device is booted to the system partition. To enter diagnostic mode, [WarriorRocker] had to press enter over and over during the boot sequence in order to kill the automatic boot process. Then he checked some environment variables to locate the memory address where the diagnostic mode is stored. One more command tells the system to boot to that address and into diagnostic mode.

The last step of the process begins by mounting the Kindle as a USB storage device and copying over the stock Kindle firmware image. Next [WarriorRocker] had to exit the diagnostic menu and return to a root command prompt. Finally, he used the dd command to copy the image to the Kindle’s partition bit by bit. Fifteen minutes and one reboot later and the Kindle was working just as it should. [WarriorRocker] even notes that the 3G connection still works. Not bad for $20 and an hour or two of work.

A Real-Time Networked VU Running On The ESP8266

February 17, 2015 by Ethan Zonca 21 Comments

Even though the ESP8266 WiFi chipsets are really cheap (and can be somewhat challenging to work with), they still pack a lot of processing power. For instance, [Mr.jb.swe] took one of these modules and made a stand-alone live VU meter with WS2812B LED strip. The VU runs entirely on the ESP chip, without any additional microcontroller. It’s an example we think a lot of projects could follow to do away with unused horsepower (extra microcontrollers) sometimes used to avoid programming directly on the ESP. The stuff you can do with these modules is wild… did you see this WiFi signal strength mapping project?

The ESP chipset acts as a UDP client which receives packets from a WinAmp plugin that [Mr.jb.swe] wrote. The plugin continuously calculates the dB of whatever track is playing and streams it over WiFi to his ESP8266. He also mentions that the ADC of the ESP chipset could be used to sample audio as well, although that pretty much eliminates the need for WiFi.

The whole setup is very responsive even though the processor is parsing UDP messages, driving the WS2812 strip, and driving a small OLED display for debug—and it doesn’t even use a separate microcontroller. [Mr.jb.swe] also posted snippets of his code to get you started on your own project. Check out the videos after the break to see it in action.

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