Tracking the Hamster Marathon

[Michelle Leonhart] has two Roborovski hamsters (which, despite the name, are organic animals and not mechanical). She discovered that they seem to run on the hamster wheel all the time. A little Wikipedia research turned up an interesting factoid: This particular breed of hamster is among the most active and runs the equivalent of four human marathons a night. Of course, we always believe everything we read on Wikipedia, but not [Michelle]. She set out to determine if this was an accurate statement.

She had already added a ball bearing to the critters’ wheel to silence it by cannibalizing an old VCR. What she needed was the equivalent of a hamster pedometer. A Raspberry Pi and a Hall effect sensor did the trick. At least for the raw measurement. But it still left the question: how much distance is a hamster marathon?

01_hamster_stride_measurement[Michelle] went all scientific method on the question. She determined that an average human female’s stride is 2.2 feet which works out to 2400 strides per mile. A marathon is 26.2 miles (based on the distance Pheidippides supposedly ran to inform Athens of victory after the battle of Marathon). This still left the question of the length of a hamster’s stride. Surprisingly, there was no definitive answer, and [Michelle] proposed letting them run through ink and then tracking their footsteps. Luckily, [Zed Shaw] heard about her plan on Twitter and suggested pointing a webcam up through the plastic bottom of the cage along with a scale. That did the trick and [Michelle] measured her hamster’s stride at about 0.166 feet (see right).

Now it was a simple matter of math to determine that a hamster marathon is just under 10,500 steps. Logging the data to SQLite via ThingSpeak for a month led [Michelle] to the conclusion: her hamsters didn’t run 4 marathon’s worth of steps in a night. In fact, they never really got much over 2 marathons.

Does [Michelle] have lazy hamsters, or did she just add to our body of scientific knowledge about rodents? We don’t know. But we couldn’t help but admire her methods and her open source data logging code would probably be useful for some non-hamster activities.

If you are super competitive, you could use [Michelle’s] data to handicap yourself and challenge your pets to a race. But it would probably be cooler to build them their own Starship Trooper-style walkers. Either way, you can check out [Michelle’s] little marathon runners in the video below.

It’s Time to Roll Your Own Smartwatch

Giant wristwatches are so hot right now. This is a good thing, because it means they’re available at many price points. Aim just low enough on the scale and you can have a pre-constructed chassis for building your own smartwatch. That’s exactly what [benhur] did, combining a GY-87 10-DOF module, an I²C OLED display, and an Arduino Pro Mini.

The watch uses one button to cycle through its different modes. Date and time are up first, naturally. The next screen shows the current temperature, altitude, and barometric pressure. Compass mode is after that, and then a readout showing your step count and kilocalories burned.

In previous iterations, the watch communicated over Bluetooth to Windows Phone, but it drew too much power. With each new hardware rev, [benhur] made significant strides in battery life, going from one hour to fourteen to a full twenty-fours.

Take the full tour of [benhur]’s smartwatch after the break. He’s open to ideas for the next generation, so share your insight with him in the comments. We’d like to see some kind of feedback system that tells us when we’ve been pounding away at the Model M for too long.  Continue reading “It’s Time to Roll Your Own Smartwatch”

$4 volt meter from a dollar store pedometer

[Paulo]’s got a few solar panels on his shed, and while he does have a fairly nice setup with a battery charge controller, he found himself looking around for a panel voltmeter. Of course you can buy a panel voltmeter for under $20, but [Paulo] wanted something that fit his 4-4-4 plan; his voltmeter should cost under $4, draw less than 4mA, and last for 4 years. The jury is still out on the 4 year qualifier, but he did manage to meet his other goals by repurposing a dollar store pedometer as a voltmeter.

The pedometer in question is a very simple device. After inspecting the PCB, [Paulo] found it operates by looking at a trigger pin and incrementing the number on the display each time the circuit closed. [Paul] designed a very small PIC12F-powered circuit that reads the voltage of his batteries and triggers the pedometer’s LCD for every 10th of a volt. To display 12.6 Volts, [Paulo]’s code triggers the LCD 126 times, for example.

After wiring up the reset button so the display will go back down to zero for each new reading, [Paulo] encased his new volt meter in a plastic box. It’s not exactly a fast way of measuring voltage, but seeing as how that won’t change very fast, it’s the perfect solution for [Paulo]’s solar charger setup.