Test Ideas Now With Sensors Already In Your Pocket

When project inspiration strikes, we’d love to do some quick tests immediately to investigate feasibility. Sadly we’re usually far from our workbench and its collection of sensor modules. This is especially frustrating when the desired sensor is in the smartphone we’re holding, standing near whatever triggered the inspiration. We could download a compass app, or a bubble level app, or something similar to glimpse sensor activity. But if we’re going to download an app, consider Google’s Science Journal app.

It was designed to be an educational resource, turning a smartphone’s sensor array into a pocket laboratory instrument and notebook for students. Fortunately it will work just as well for makers experimenting with project ideas. The exact list of sensors will depend on the specific iOS/Android device, but we can select a sensor and see its output graphed in real-time. This graph can also be recorded into the journal for later analysis.

Science Journal was recently given a promotional push by the band OK Go, as part of their OK Go Sandbox project encouraging students to explore, experiment, and learn. This is right up the alley for OK Go, who has a track record of making music videos that score high on maker appeal. Fans would enjoy their videos explaining behind-the-scene details in the context of math, science, and music.

An interesting side note. Anyone who’s been to Hackaday Superconference or one of the monthly Hackaday LA meetups will likely recognized the venue used in many of the OK Go Sandbox videos. Many of them were filmed at the Supplyframe Design Lab in Pasadena. It’s also nice to see AnnMarie Thomas (Hackaday Prize Judge from 2016 and 2017) collaborated with OK Go for the Sandbox project.

While the Science Journal app has provisions for add-on external sensors, carrying them around would reduce its handy always-available appeal. Not that we’re against pairing smartphones with clever accessories to boost their sensing capabilities: we love them! From trying to turn a smartphone into a Tricorder, to an inexpensive microscope, to exploring serious medical diagnosis, our pocket computers can do it all.

[via Engadget]

 

Fingerling Disemboweled for Your Entertainment

Due to the graphic nature of this post, small children and the elderly may want to leave the room. One of the hottest toys this holiday season has been gutted like a fish so that we may better understand the nature of its existence. Or maybe just what kind of sensors and motors the craftsmen over at WowWee managed to cram into a “robot” with an MSRP of only $15 USD.

[Josh Levine] mercilessly tears a Fingerling Monkey limb from limb on his blog, and points out some interesting design decisions made. While some elements of the toy are rather clever, there’s a few head-scratchers to be had inside the Fingerling. It’s interesting to see the final results of a decision process that had to balance the relatively rough life such a toy will live with the ever crucial cost of production.

The eyelids are particularly well thought out, operated by charging a coil under a magnet which is embedded in the plastic. Opening and closing the eyelids without a separate motor or gearbox is not only easier and cheaper, but prevents the possibility of damage if a child attempts to force open the eyes or otherwise manipulate the mechanism.

Other cost saving measures include the use of foil tape as a capacitive sensor, and simple ball-filled tilt sensors to detect orientation rather than an expensive accelerometer.

Interestingly, other parts of the toy seem overengineered in comparison. A cam and limit switch are used to detect when the Fingerling’s head has turned to its maximum angle, when it would have been cheaper and easier to simply detect motor stall current.

If you’re interested in seeing what makes popular toys tick, we’ve got a number of plaything tear downs which are sure to keep you satiated until the next big holiday toy rolls around.

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Clever And Elegant Tilt Sensors From Ferrofluid

Let’s talk about tilt sensors for a second. The simplest tilt sensors – the dead simplest – are a few ball bearings rolling around in a small metal can. When the can is tilted, the balls roll into a pair of electrical contacts, completing the circuit. How about a drop of mercury in a glass ampule with a few contacts? Same thing. You can get more expensive tilt sensors, including a few that are basically MEMS gyros, but they’re all pretty much the same. For [Aron]’s project for the Hackaday Prize, he’s come up with a tilt sensor that is so clever, so innovative, and so elegant, we’re gobsmacked by his creativity.

5700111461442877186Instead of electrical contacts or gyroscopes, [Aron] is using induction to measure the tilt of a sensor. By wrapping a tube with one long primary winding of copper wire, and several secondary windings in various places, [Aron] built a Linear Variable Differential Transformer. If you insert an iron rod inside this transformer, different voltages will be induced in the primary. Simple, and this device is effectively a position sensor for any ferrous material.

Now for the real trick: put ferrofluid in the core of that transformer. Liquids always find their level, and different tilts will induce different voltages in the primary. Brilliant. Continue reading “Clever And Elegant Tilt Sensors From Ferrofluid”

Dog Tracker Knows Where the Dirt is

[Eric] is well on his way to making one of the less pleasant chores of pet ownership a bit easier with his dog tracking system. The dog tracker is actually a small part of [Eric’s] much larger OpenHAB system, which we featured back in July.

As a dog owner, [Eric] hates searching the yard for his pet’s droppings. He had been planning a system to make this easier, and a local hackerspace event provided just the opportunity to flesh his ideas out. The Dog Tracker’s primary sensor is a GPS. Most dogs remain motionless for a few seconds while they go about their business. [Eric’s] Arduino-frgbased system uses this fact, coupled with a tilt sensor to determine if the family pet has left any presents.

The tracker relays this information to the home base station using a HopeRF RFM69 transceiver. The RFM69 only has about a 900 foot range, so folks with larger properties will probably want to spring for a cellular network based tracking system. Once the droppings have been tracked, OpenHAB has an interface

[Eric] has also covered runaway dogs in his design. If Fido passes a geo-fence, OpenHAB will raise the alarm. A handheld dog tracker with its own RFM69 can be used to chase down dogs on the run. Future plans are to miniaturize the dog tracker such that it will be more comfortable for a dog to wear.

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DIY 3D Tilt Sensor

tilt If you’re trying to detect the orientation of an object, sometimes you really don’t need a 6DOF gyro and accelerometer. Hell, if you only need to detect if an object is tilted, you can get a simple “ball in a tube” tilt sensor for pennies. [tamberg] liked this idea, but he required a tilt sensor that works in the X, Y, and Z axes. Expanding on the ‘ball in a tube’ construction of simple tilt sensors, he designed a laser cut 3D tilt sensor that does all the work of of a $30 IMU.

The basic design of this tilt sensor is pretty simple – just an octahedron with four nails serving as switch contacts at each vertex. An aluminum ball knocks around inside this contraption, closing the nail head switches depending on what orientation it’s in. Simple, and the three dimensional version of a ball in tube tilt sensor.

To get the tilt data to the outside world, [tamberg] is using an Adafruit Bluetooth module, with two of the nails in each corner connected to a pin. With just a little bit of code, this 3D tilt sensor becomes a six-way switch to control an RGB LED. Video of that below.

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5 cent tilt sensor

5cent

This is a 5 cent tilt sensor. We know it cost more than 5 cents, but it is in fact a tilt sensor that utilizes a 5 cent coin. We’ve all done quick hacks to make quick sensors for various projects. We’ve seen tons of them, from stealing springs out of pens and shoving a resistor through them for flexible contact switches, to tin foil touch sensors. This one is new to us though. The design is fairly simple, you insert 4 bits of wire to serve as contacts and the coin will make contact with only two at a time. It isn’t analog, it isn’t extremely precise, but it is super quick and easy. Thanks for sharing [ix].