Adding a heart rate monitor to your exercise equipment

This is the readout which [Remick] added to his stationary bicycle. It displays heart rate, calories burned, and a few other items to help motivate his workout routine.

Back when he was ordering a TI Chronos watch he also picked up a heart rate chest strap and receiver. The receiver can be read using a UART, making it easy to interface with the ATmega328 which drives the system. The screen is a graphic LCD, which gave him a lot of control on how to organize the displayed data. Three buttons on the side operate the menu system into which a user can enter sex, age, and weight information. This is used to calculate the calories burned and the percentage of maximum heart rate. The three readouts to the right are for time spent in each workout zone (fat burning, fitness, or performance). The final product looks great because of the PCB he etched and the case he housed it in.

Easy workout logging with Ethernet-enabled exercise bike

It will be easy to keep your exercise routine on track if you don’t have to do anything at all to log your workouts. [Reefab] developed this add-on hardware for his exercise bike that automatically logs his workout on the Internet.

He’s using RunKeeper to store and display the workout data. They offer a token-based API which [Reefab] implemented in his Arduino sketch. The hardware to grab data from the exercise bike is quite simple to set up. A rare-earth magnet was added to the fly-wheel with a reed switch positioned next it in order to measure the number and speed of rotations. This is exactly how a consumer bicycle computer works, needing just one accurate measurement corresponding to how far the bike travels with each revolution of that wheel.

In addition to the networked-logging feature [Reefab] included a character display so you can follow your speed and distance data during the workout.

Pushing chest strap heart rate to a stock exerciser display

This hack came out so well that [Levent] wishes he had tried it years ago. When exercising he wears a Polar heart rate monitor which sends data from a chest strap to his wristwatch. But his exercise bike also has a heart rate readout that depends on your hands touching metal contacts on the handlebars. He set out to see if he could patch the chest strap data into the exercise bike LCD display.

The first part of the hack is really simple. As we’ve seen several times before, you can buy a receiver module which grabs data from the chest strap. Now it was a matter of patching the data from this receiver into the Schwinn 213 recumbent exercise bike. [Levent] pulled out the PCB and located the small daughterboard that is responsible for the hand grip heart rate. With careful study he was able to identify the pinout. There are two data lines. One is responsible for the heart rate detected signal, the other pushes the actual heart rate data. On a hunch he hooked a signal generator up to the latter and discovered that all it takes is a square wave.

The rest is pretty straight forward. Check out the proof in his video after the break. [Read more...]

Lose the beer belly by brewing beer

If you’re milling your own grains for that next batch of beer you might be able to melt all of those extra calories away while you’re at it. [Eucherboy1] repurposed an unused exercise bike to power his grain mill. The propane tank is serving as a weight to hold the base of the mill in place; it’ll be used later when boiling the wort. A belt transfers power from the bike to a wheel replacing the hand crank on the mill. Check out the video after the break to see [Euchreboy1] working up a sweat. We think there’s much room for improving the gear ratio of the setup. Or he can just man up and push through the pain.

We’ve gotten used to seeing ways to power a bicycle, like using wood-fired steam, or even by incorporating a chainsaw. But the hacks that use a bike as a power source are a bit less common. Our local hackerspace made a bicycle blender a while back. Got any projects of your own that are bike powered? Send them our way!

[Read more...]

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