Too Hot for Fido? Get Alerted!

Meet project Oro, the temperature monitoring watchdog. Err… the watchdog monitoring temperature probe. Well, it’s both actually!

[Richard Deininger] built the project after having the AC system go down in his company’s server room. That environmental cooling is imperative if you don’t want your server hardware turned to slag. The idea is a separate piece of hardware that monitors the room temperature and will alert the on-call staff if it climbs too high. He was successful, and showing the hacked hardware around the office came up with a second idea: a temperature sensor for your car to ensure it’s not too hot for your dog.

Anyone who has a canine friend living with them knows you don’t utter the word “ride” out loud lest a barking, whimpering, whining frenzy ensue. But jingle those keys and they’ll be at the door in no time. During the summer you can still take them with you for short errands thanks to the peace of mind [Richard’s] build provides. It’s simply an Arduino, DHT22 temp/humidity probe, and a SIM900 GSM modem. Set your temperature threshold and you’ll get an alert if temperatures are climbing to unsafe levels for Fido.

While you have your tools out, we recommend building auto-watering and auto-feeding systems for the family pets. What’s that? You hate domesticated animals? There’s a hack you can use to chase them from your yard.

Hackaday Prize Entry: Building A Car, From Scratch, Out Of Foam

Want an impressive example of what a few people can do in a garage? How about building an electric car, from scratch, starting with a gigantic chunk of foam?

The Luka EV from [MW Motors] had a few project aims: it should be all-electric, naturally, with a top speed of 130km/h or 80mph. It should have a range of over 300km, and it should look good. That last line item is tricky; it’s not too hard to build an electric car, but to make one look good is a challenge.

The design of the car actually started out as a digital file. A large block of foam was acquired and carefully carved into the desired shape. This foam is covered fiberglass, and parts are pulled off this fiberglass mold. This is a great way to do low-volume production – once the molds are complete, it’s a relatively simple matter to build another body for a second Luka EV.

With all the lights, accessories, windows, and trim installed, it’s time to put this body on a chassis. This was welded out of square tube and serves as a test rig that can be independent of the mess of fiberglass. In the chassis are batteries, suspension, motor controllers, and wheels loaded up with hub motors. It works well, even with one motor.

There’s a lot more to this project, including a great guide on building a road legal car in the UK. The team isn’t based in the UK, but it’s a much more friendly environment for ‘small series’ vehicles. The requirements are easy to meet – “have a horn”, for example – but there are a lot of them.

Already the car is beautiful, and that’s just with it sitting on a trailer. We can’t wait to see this thing hit the road.

The 2015 Hackaday Prize is sponsored by:

Hack a Lock, Get a Free Car?

No, we’re not talking about any lock, or car for that matter. The creators of Loxet are so confident in their product, a smart lock for your car, they’ve issued a challenge to the world. If you can defeat it, you can keep the car — sadly the car isn’t anything special though.

The device, after installed on your vehicle, gives you a taste of the premium lifestyle of fancy push-to-start vehicles. It automatically unlocks your vehicle when you come near with your cellphone, and only your cellphone. It also has the option to give access to friends and family using an invite system. It controls ignition access, and works as a proximity lock.

The car is located at ul. Straszewskiego 14 in Krakow. If you’re not from Poland, [Matt] recommends you team up with a local to try your hack. The alternate prize (if you’re not from Poland or don’t want the car) is $2000.

The car is just sitting there. We’d love to see some 1st person attempts from any of our Polish readers living in Krakow! It is currently set to unlock and lock every 10 minutes. You might be able to get into the vehicle — but will you be able to take it? Let us know!

Continue reading “Hack a Lock, Get a Free Car?”

DIY Car Wheel Bearing Puller

Cars are the greatest. They get you to where you need to go… most of the time. They can also let you down at the worst moment if a critical part fails.  Wheel bearings get a lot of use while we drive and [Dmitriy] found out the hard way how quickly they can fail. Instead of getting cranky about it, he set out to change the damaged bearing himself. In the process he made a pretty neat DIY bearing puller.

Some wheel bearings, on the front of a 2WD truck for example, are only held on by one large nut and easily slide off the spindle. This was not the case for the rear of [Dmitriy’s] AWD Subaru. The rear bearings are press-fit into a bearing housing. These are hard to remove because Outer Diameter of the bearing is actually just slightly larger than the Inner Diameter of the bearing housing. This method of retaining parts together is called an ‘interference fit‘.


[Dmitriy’s] gadget uses one of Hackaday’s favorite simple machines, the screw, to slowly force the bearing out of its housing. It works by inserting a threaded rod through the bearing and bearing housing. Each side has a large washer and nut installed as well as a PVC pipe spacer providing support for the threaded rod. As the opposing nuts are tightened, one washer presses against the bearing and the bearing slowly slides out of the housing. Installation of the new bearing is the same except the tool is reversed to press the bushing into the housing.

Continue reading “DIY Car Wheel Bearing Puller”

DIY iPhone Mount for a Volvo

[Seandavid010] recently purchased a 2004 Volvo. He really liked the car except for the fact that it was missing some more modern features. He didn’t come stock with any navigation system or Bluetooth capabilities. After adding Bluetooth functionality to the stock stereo himself, he realized he would need a secure location to place his iPhone. This would allow him to control the stereo or use the navigation functions with ease. He ended up building a custom iPhone mount in just a single afternoon.

The key to this project is that the Volvo has an empty pocket on the left side of the stereo. It’s an oddly shaped vertical pocket that doesn’t seem to have any real use. [Seandavid010] decided this would be the perfect place to mount his phone. The only problem was that he didn’t want to make any permanent changes to his car. This meant no drilling into the dash and no gluing.

[Seandavid010] started by lining the pocket with blue masking tape. He then added an additional lining of plastic wrap. All of this was to protect the dashboard from what was to come next. He filled about half of the pocket with epoxy putty. We’ve seen this stuff used before in a similar project. He left a small opening in the middle with a thick washer mounted perpendicular to the ground. The washer would provide a place for an off-the-shelf iPhone holder to mount onto. [Seandavid010] also placed a flat, wooden paint stirrer underneath the putty. This created a pocket that would allow him to route cables and adapters underneath this new mount.

After letting the epoxy putty cure for an hour, he removed the block from the pocket. The stick was then removed, and any gaps were filled in with putty. The whole block was trimmed and smooth down for a more streamlined look. Finally, it was painted over with some flat black spray paint to match the color of the dashboard. An aftermarket iPhone holder allows [Seandavid010] to mount his cell phone to this new bracket. The cell phone holder allows him to rotate the phone into portrait or landscape mode, and even is adjustable to accommodate different sized phones.

Custom Double-Din Mount for Nexus 7 Carputer

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.

[Mike] Shows Us How to Use an Armature Growler

[Mike] has put up a great video  on his [SmallEngineMechanic] YouTube Channel about a tool we don’t see very often these days. He’s using an armature growler (YouTube link) to test the armature from a generator. Armature growlers (or just growlers for short) were commonplace years ago. Back when cars had generators, just about every auto mechanic had one on hand. They perform three simple tests: Check armature windings for shorts to other windings, for open windings, and for shorts to the armature body. [Mike’s] particular growler came to him as a basket case. The wiring was shot, it was rusty, and generally needed quite a bit of TLC. He restored it to like new condition, and uses it to help with his antique engine and genset addiction hobby.

Growlers essentially are a transformer primary with a V-shaped frame. The primary coil is connected to A/C mains. The armature to be tested sits in the “V” and through the magic of induction, some of the windings become the secondary coils (more on this later). This means some pretty high voltage will be exposed on commutator of the armature under test, so care should be taken when using one!

Testing for shorts to the ground or the core of the armature is a simple continuity test. Instead of a piezo beep though, a short will trigger the growler to turn on, which means the armature will jump a bit and everything will emit a loud A/C hum. It certainly makes testing more interesting!

Checking for open windings is a matter of energizing the growler’s coil, then probing pairs of contacts on the commutator.  Voltage induced in the windings is displayed on the growler’s meter. Open windings will show 0 volts. Not all the armature’s windings will be in the field of the growler at once – so fully testing the armature will mean rotating it several times, as [Mike] shows in his video.

The final test is for shorted coils. This is where things get pretty darn cool. The growler is switched on and a thin piece of ferrous metal – usually an old hacksaw blade, is run along the core of the armature. If a short exists, the hacksaw blade will vibrate against the core of the armature above the shorted windings. We’re not 100% clear on how the coupling between the growler’s primary and two windings causes the blade to vibrate, so feel free to chime in over in the comments to explain things.

Most commercial shops don’t troubleshoot armatures anymore, they just slap new parts in until everything works again. As such the growler isn’t as popular as it once was. Still, if you work with DC motors or generators, it’s a great tool to have around, and it’s operation is a pretty darn cool hack in itself.

Click past the break for [Mike’s] video!

Continue reading “[Mike] Shows Us How to Use an Armature Growler”