Hack a Day

[Ralph Doncaster] has a geothermal heat pump which is responsible for providing heat for his home. He’s been looking into some hacks that would make it more efficient and decided that the freon (R-22) needed to be tweaked. Some would say the stuff is bad for the environment, so he decided to go a different route. He replaced the Freon with propane, using this rig to make the fuel-grade propane more like cooling-grade propane called r-290.

He purchased the gauge set which is used whenever a technician services an A/C system (but you can also see it in this other A/C propane hack). That’s important because it’s responsible for making sure the old coolant is recaptured (his hose failure nixed this part of the plan) and the new coolant goes where it should at the correct pressure. But before dumping in propane from the local hardware store he needs to dry it out. Fuel-grade propane can have moisture in it, which can be bad for the cooling system. He bought a drier device, the grey bulb seen above, and soldered it on one end to a propane torch fitting and to a valve connection on the other. Now he could remove moisture as he pressurized the system.

Everything is working again, and the cooling side of the system gets much colder. He plans to do more testing as time goes by.

If you’re a follower of Apple hardware the upcoming Google Glass release probably doesn’t interest you much. But the concept is universally cool. If you want to have your own one-eyed voice-activated computer running iOS, then this is the hack for you. [John] calls it the Beady-i, and posted a step-by-step article on how he put it together.

The headpiece is shown on the left. It’s a combination of a pair of glasses with projection screens built-in, and a gaming headset. [John] cut off one of the lenses, and removed the remaining arm of the glasses. That arm was replaced with the frame of a gaming headset, which now wraps around the back of his neck to make sure the lopsided display isn’t going to fall off.

By combining the electronics from both the glasses and the headset, and terminating the connections with a docking plug he’s got what he was after. The lens displays what is shown on the screen, and the gaming headset lets him hear the device’s sound in one ear and register input using the microphone.

PC board houses are getting more accessable and less expensive all the time. Some of us are even getting very, very good at making our own circuit boards at home. There are times, though, when a project or prototype requires an extremely cheap custom board right now, something etching a custom board won’t allow. [KopfKopfKopfAffe] has a unique solution to this problem, able to create custom boards in under an hour without any nasty chemicals.

Instead of starting his build with copper-clad board, [KopfAffe] used every rapid prototyper’s friend, simple one-sided perf board. The shape of the board was milled out on a CNC machine, and both the top silk screen and bottom layer were marked off using the toner transfer method. After that, a custom circuit is just a matter of placing components and putting solder bridges between all the marked pads.

[KopfAffe] is only using this technique for single-sided boards, but we don’t see any reason why it couldn’t be employed for simple double-sided boards. This would still have the problem of making vias between the layers, but that’s still a problem with proper, home-etched double sided boards.

Properly configured, your computer will go into sleep mode when left unattended for a long enough time. So will your cell phone, and just about every other piece of sufficiently complex electronics. Much simpler circuits, though, are left at the mercy of a SPST switch; if you forget to turn a flashlight off, it will be dead next time you need to use it. Wanting an auto-off circuit simple electronics, [Kyle] threw together this auto shutoff circuit.

The basic idea behind the cirucuit is to use a microcontroller as a timer controlling two transistors. When [Kyle]‘s circuit is power cycled, the timer inside an AVR starts, making a pin high, and when the timer is up, making the pin low again. This pin feeds into a PNP transistor which is in turn connected to a NPN transistor, creating a very tiny auto off circuit for anything with an SPST switch.

[Kyle] says there are a few improvements to be made – using MOSFETS to handle higher currents and possibly using a smaller microntroller like an ATtiny 4/5/9/10 to shrink the circuit’s volume. It’s a great idea, bringing the idea of a flashlight with auto shutoff into reality.

There’s a problem with collecting old tube amps and vintage electronics – eventually the capacitors in these machines will die. It’s not an issue of a capacitor plague that causes new electronics to die after a few years; with time, just about every capacitor will dry out, rendering antique electronics defective. The solution to getting old gear up and running is replacing the capacitors, but how do you know which ones are good and which are bad? With [Paulo]‘s DIY ESR meter, of course.

An ideal capacitor has a zero equivalent series resistance, and failure of a capacitor can be seen as an increase in its ESR. Commercial ESR meters are relatively cheap, but [Paulo] was able to build one out of a 555 chip, a small transformer, and a few other miscellaneous components.

The entire circuit is built on stripboard, and if you’re lucky enough to find the right parts in your random parts bin, you should be able to build this ESR meter with components just laying around.

[furrysalamander] has a friend that is a really big Doctor Who fan. It happens that this friend has a birthday coming up, and [furrysalamander] wanted to get her something amazing. A Sonic Screwdriver is always a great gift, but [furrysalamander] wanted to put his personal touch on it. He ended up adding a TV-B-Gone to [10]‘s screwdriver, turning a fictional deus ex machina into a functional device.

The body of the Sonic comes from this replica of [10]‘s screwdriver from Think Geek. Inside, the screwdriver has space for a battery a circuit board to control the lights and sound normally expected of a sonic screwdriver. [furrysalamander] added a freeform circuit composed of an ATtiny85, a transistor, LED, and a few resistors to add the ability to turn just about any TV off.

Of course [furrysalamander] needed to program the ATtiny with the TV-B-Gone firmware, and lacking any AVR development tools he used a Raspberry Pi’s GPIO pins to write the firmware to the microcontroller. That’s something we’ve seen before, but [furrysalamander] is a champ for including the process in his Instructable.

The end result is a Sonic Screwdriver that doesn’t work on wood and can’t break a deadlock seal. It turns off TVs just fine, though, and looks great to boot. You can check out a demo of [furrysalamander]‘s sonic in action after the break.

Ever wondered just how much being zapped by electricity hurts? Curious if AC is worse than DC? Want to know just how many volts a human body can take? Although many people might cringe at the shear thought of it, [Mehdi Sadaghdar] is an electrical engineer who decided to turn himself into a human guinea pig and find out.

[Mehdi] measured the electrical resistance of his dry skin, his wet skin, and finally his tongue.  He found that his tongue had the least resistance, so it would feel the electricity at much lower levels. Using a bench power supply, he then used his tongue as a testing ground – slowly turning the voltage up and up until he could no longer take the pain. He tested the levels at which: he could first feel the electricity, when it began to get annoying, when it felt like torture, and when he could no longer stand the pain. He tried both AC and DC, and reports that AC is much worse.

Check out the informative, yet admittedly hilarious at times, video after the break. [Mehdi] seems like one awesome engineer! Remember – don’t try this at home.

We’re a US-centric site, but aside from events in New York or California, we don’t see many hacker, maker, or 3D printer events aimed at the parts of the country filled with corn and WalMarts. The 1st annual Midwest RepRap Festival aims to change that with enough events, speakers, and activities to make Elkhart, Indiana look like the hoppingist place around.

Officially, the festival started yesterday but the schedule of events really ramps up today. [Josef Prusa] will be taking the stage talking about the state of the RepRap, and a ton of 3d printing vendors will be there showing off their wares and selling some really cool stuff. There’s also tons of experienced RepRappers available to help you tune your machine to perfection; just as well, because the festival is going for the world record for the greatest number of 3D printers printing simultaneously.

If you’re around northern Indiana, you might want to check out the festival and send us a few pics or videos.

Here’s a fun way to break up the monotony in the old cubicle farm. The Mug Plotter will let you expertly inscribe your coffee vessel with a different witty saying or design for each day of the week. If it looks familiar that’s because it’s loosely based on the non-flat drawing robot, the Eggbot.

[Teed] built the machine using laser cut plywood parts. He starts off the build description with the griping technique. There are two parts to this, one is concave and fits in the mouth of the mug. The convex side grips the bottom edges of it. These parts go on the frame along with the slide and thread rods which hold the stylus. A servo motor is along for the ride, providing the ability to lift the marker when necessary.

You can see in the clip after the break that there’s a bit of oscillation in the rig when one of the steppers starts turning really fast. But it doesn’t seem to affect the look of the design very much at all.

We don’t know if typing your Facebook updates from a piano keyboard counts as practicing or not. But if you want to give it a try here’s how. [Zach] wrote in to our tips line with his latest ASETNIOP hack which uses a MIDI piano keyboard to touch type on a computer.

Last July was when we first heard about ASETNIOP. It’s a chorded typing system which at the time was aimed at, but not limited to, touch screen devices. This version gives a pretty good idea of how the system actually works. Your fingers and thumbs are each assigned a key and they never move away from it. To type more than just the ten letters, combinations of keys are assigned the rest of the alphabet. You can see the piano example of the system after the break. But better yet would be hooking your own MIDI keyboard up to the computer and trying it in a browser.

After years of prototyping hobby electronics we’ve learned (several times actually) that when something’s not working it’s a problem with the hardware. Usually the jumper wires aren’t hooked up correctly, or we needed to throw a pull-up resistor in and forgot to. One thing that can really help sort these problems out quickly is a pinout label for each chip like the ones seen above. This is a project which [John Meacham] came up with. It uses a script to generate chip pinouts on a label maker.

The label maker he started with is a Brother PT-1230PC. It connects to a computer via USB and can use a few different widths of self adhesive label tape. [John] found that the 1/4″ wide tape is nearly a perfect fit for PDIP components.

His script takes a YAML file as the input. This formatting standard makes is quick an easy to whip up a label for a new chip using just your text editor. From there his Pearl script turns the data into a Portable Network Graphics (.png) file with the labels spaced for the 0.1″ pitch of the chip. Send this graphic to your label maker and you’ve got an adhesive reminder that will help reduce the time you spend pawing through datasheets just for the pinouts.

[James] has an admirable home automation system which he’s been working on for years. It does things like monitor the state of the garage door, control the lights, and it even notifies him of a power failure. One thing that wasn’t on the system yet are the fireplaces he has in his home. The hardware you see above is how he patched into the fireplace remote control system in order to automate them.

The remote control uses RF to communicate with a base station. Unlike controlling home theater components which use IR, this makes it a bit more difficult to patch into. Sure, we’d love to see some reverse engineering of the protocol so that a simple radio module could be used, but [James] chose the route which would mean the least amount of hacking on his part. He soldered wires onto the PCB for the buttons and connected to them using reed relays. These let the Arduino simulate button presses.

With the rig connected to the home network he has a lot of options. The system can sense if the house is occupied. If it determines that no one is home it will switch off the fireplaces. [James] also mentions the ability to monitor for carbon monoxide or house fires, switching off the gas fireplaces in either case.

The value of a 3D printer is obvious for people who hack hardware as a hobby. But this repair project should drive home their usefulness for the commoner. [James Bruton] used a 3D printer to recreate a hopelessly broken injection molded plastic part. This is a suction cup mounting bracket for a Tom Tom GPS module. The sphere which makes it adjustable had broken off of the column holding it. For 100% of non-hacking consumers that’s the end of this item. We can’t see a fix that would restore the strength of the original part.

The replacement starts by measuring the broken part with precision calipers. [James] then grabbed a copy of 123D, which is free software. He starts by modeling the sphere, then builds up the support column and the base with a cut-out. It’s obvious he’s already very familiar with the software, but even the uninitiated should be able to get this done pretty quickly. After slicing the design for the 3D printer he finds the part will be ready in about 11 minutes. The first prototype is a bit too small (the ball requires close tolerances to work well). He spins up a second version which is a bit large and uneven. A few minutes of filing leaves him with a smooth sphere which replaces the original part beautifully!

You can see the entire design, print, and assembly process in the clip after the break.

When [Andrei] first got his Raspberry Pi he wanted to make it a standalone computer right away. This means the normal input devices like a mouse and keyboard, but also some type of display. To avoid waiting for shipping he ended up using a cheap vehicle backup camera screen from the local big box store. It worked great, and recently he decided he would try to convert it to run off of 5V power to simplify his setup. While snooping around inside the device he discovered an unused resistive touch overlay and figured out how to get it to work.

What tipped him off is the small four-conductor connector which wasn’t hooked up to anything. He carefully soldered wires onto the flexible circuit traces, then generously covered them in hot glue to help prevent movement from breaking the rigid connection. To get this working you need to measure the resistance between the conductors. Most of the time we figure the RPi GPIO header can be used directly, but for this task an intermediary is necessary. [Andrei] went with a small Arduino clone board. A bit of trial and error was all it took to get the connections right and to iron out the code which translates the values into coordinates.

[Kasey] and [Guyzmo] have been working for the past couple of years on a side project that lets them monitor pollution using a network of sensors. They’ve just decided to make the project open source, both hardware and software. The details of the system are available at their GitHub repository.

There are two main components to the system. On the right is a base station which collects the data from the array of sensor, one of which is shown on the left. Each sensor runs off of a battery, but features a PV solar panel which keeps the power source topped off. It uses an Arduino to drive the system, and an XBee radio for communications. Some info about the sensors can be found on this summary page. There’s a PM10 particle pollution sensor, temperature, sound, nitrogen, and oxygen sensors. We also wonder if any data can be gleaned from how much electricity the solar panel is able to harvest?

The base station also uses an XBee radio to poll the network, but it’s not driven by an Arduino. They’ve gone with the ARM-based BeagleBone to manage the data.

[Ezra] used the parts he had lying around to build a self-contained dual screen shop computer. What might one name such a project? Obviously you’d call it the Dr. FrankenComputer.

The lower monitor is a dell desktop flat screen. During prototyping [Ezra] used the stand to support everything. But to keep his work space clear the final version has been mounted to the wall in the corner of his lab. The upper display is the LCD from a Compaq laptop which he wasn’t using. The laptop still works and we believe that’s what is driving the Fedora system. A bracket mounted to the desktop screen’s inner skeleton supports the laptop screen and motherboard. One power supply feeds everything and connects to an outlet in the wall behind the monitors. The keyboard and mouse are wireless, as is the computer’s connection to the network.

The only thing we would worry about in our own shop is sawdust filling the heat sinks and other components of the motherboard. Perhaps his lab is electronic projects only or he has a dust cover that he uses when the system isn’t in use.

We’re really starting to enjoy the home entertainment control hacks which use a universal receiver to act on commands from any remote. This one is especially interesting as it uses a single remote to control the system but rolls in lots of extras.

Looking at the receiver itself the white plastic dome of the PIR sensor should raise an eyebrow. Since the cable box takes a while to turn on [Ivan] included the motion sensor to switch that component on when you walk into the room. This way it’ll be ready to go by the time you sit down. It does this by sending IR signals from the PIC32 dev board. Of course the board has its own receiver to listen for the remote control commands. The remote buttons have been mapped a bit differently than originally intended. You can see in the diagram above that the normal VCR/DVD/DVR buttons have been set to control the room’s LED strips. There’s even a power consumption monitor rolled into the project. All of these features are demonstrated in the clip after the break.

This is a nearly perfect base setup. But we’d love to see it with a web interface at some point in the future.

[Gnif] was doing what any good hacker does… poking around the insides of one of his tools to see how it works. While in there, he discovered that an EEPROM hack could make the Agilent U1241A function like the U1242A.

If you’re into this kind of thing the Rigol 1052e hack should have already popped to mind. That was a firmware crippled device that, when unlocked, made the cheaper model behave the same ways as it’s $400 more expensive sibling. This doesn’t have quite the same impact, as the price difference is somewhere between $20-$100. Still, this stuff is just cool, right?

A few posts down in the thread linked above [Gnif] shares the story of how he found the hack. After shorting the i2c lines of the EEPROM while powering up the meter he was able to see that the device initializes a lot of its values to 0xFF when it can’t find the stored data. The next step was to use an STM32 board to dump the EEPROM contents. With the backup file stored safely he started changing values and reflashing the chip. Through this process he discovered that switching one byte from 0×01 to 0×02 enabled the higher model’s features. It also works for upgrading the U1732C to the U1733C feature set.

Meet Cubli, a research project which aims to make a cube that can walk around without using any appendages. It’s a research project at the Institute for Dynamic Systems and control in Switzerland. Anyone else thinking about our beloved companion cube right now?

The robotic experiments are based on angular momentum. Inside of the cube there are center mounted motors which each spin a wheel. Three of these are mounted perpendicular to each other to give the cube the ability to change its position along any axis. This is best shown by the first video after the break where just a single side of the assembly is demonstrated. A square frame starts at a rest position. You see the wheel spin up and it is suddenly stopped, which causes the momentum of the wheel to pop the square frame up onto one corner. The wheel then switches into a second mode to keep it balancing there. The final mode is a controlled fall. This theoretically will let the cube move around by falling end over end. So far they’re not showing off that ability, but the second demo video does show the assembled cube balancing on one corner.

[Reddit via Robohub]

The cheap software defined radio platforms that can be built out of a USB TV tuner aren’t getting much love on the Hackaday tip line of late. Thankfully, [Adam] sent in a great guide to cracking sub-GHz wireless protocols wide open, and ringing doorbells, opening cars, and potentially setting houses on fire in the process.

The first wireless hack [Adam] managed to whip up is figuring out how a wireless doorbell transmitter communicates with its receiver. [Adam] connected a FUNcube software defined radio dongle (although any one of the many USB TV tuner dongles we’ve seen would also work) and used GNU Radio to send the radio signals received to a WAV file. When looking at this audio file in Audacity, [Adam] saw the tell-tale signs of digital data, leaving with a string of 1s and 0s that would trigger his wireless doorbell.

The FUNcube dongle doesn’t have the ability to transmit, though, so [Adam] needed a more capable software defined radio to emulate the inner workings of a doorbell transmitter. He found one in the Ettus Research USRP, a software designed radio that’s doing a good job of keeping [Balint], Hackaday SDR extraordinaire, very busy. By sending the data [Adam] decoded with the FUNcube dongle over the USRP, he was able to trigger his wireless doorbell using nothing but a few hundred dollars of radio equipment and software ingenuity.

Doorbells are a low-stakes game, so [Adam] decided to step things up a little and unlock his son’s car by capturing and replaying the signals from a key fob remote. Modern cars use a rolling code for their keyless entry, so that entire endeavour is just a party trick. Other RF-enabled appliances, such as a remote-controlled mains outlet, are a much larger threat to home and office security, but still one [Adam] managed to crack wide open.