Pushing Chest Strap Heart Rate To A Stock Exerciser Display

November 26, 2011 by Mike Szczys 3 Comments

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. Continue reading “Pushing Chest Strap Heart Rate To A Stock Exerciser Display” →

A Doorbell Pleasing To Both The Ears And Eyes

November 22, 2011 by Mike Nathan 15 Comments

campanello-doorbell

When [David] moved into his new house, one of the things he noticed was that his doorbell was pretty lame. Coming from a home equipped with a solenoid and chime bell, his new wireless solid state doorbell sounded terrible to him.

Crummy sound aside, the doorbell hardly ever worked properly, but alas, other projects cropped up and years went by before [David] addressed his doorbell problem. Like many things that take a long time to come to fruition, we think his resonator bell based solution was well worth the wait.

One of his main goals was to make a nice sounding doorbell that also looked great. He mounted a kid’s resonator bell toy on a sheet of wood, creating his own wooden mallets for the job. He initially had a tough time locating actuators for his doorbell, but found a solution in geared pager motors as featured in another xylophone hack on Make. With the hardware taken care of he focused on the electronics, which consist of a pair of Arduino clones – one on the display and one in his basement.

Stick around to see [David’s] Campanello doorbell in action, and be sure to check out his site for more details if this sounds like something you would like to have in your home.

[via Make]

Continue reading “A Doorbell Pleasing To Both The Ears And Eyes” →

Power Strip Hack Reduces Standby Electricity Consumption

November 21, 2011 by Mike Nathan 31 Comments

computer-standby-circuit

For years, [Rasmus] has left his computer connected directly to the mains power so that he can turn it on via Wake on Lan. While powered down, it would still continuously consume about 6W of electricity, but now that he didn’t need it to be on standby so often, he wanted to make it more energy efficient.

In Denmark, where he lives, many people use power strips that have an onboard USB cable. These strips are meant to reduce the standby power consumption of PC peripherals such as monitors by powering on the mains sockets only when the computer is active. He decided the easiest way to cut his standby energy consumption to 0W would be to power his computer via this strip as well.

While it sounds great in theory, it presented a sort of chicken/egg problem. If the computer needs to be turned on for the power strip to recognize it, then how could he also supply power to the computer from the same strip? His solution was a small circuit that would charge up while the computer was running, and still hold enough juice to kickstart the PC’s boot process, thus turning on the power strip.

It really is an ingenious way to go about things, nice job!

Python Powered Sprinkler System Wastes No Water

November 19, 2011 by Mike Nathan 31 Comments

rain-gauge

One thing that annoyed [Jashua] to no end was hearing his automated sprinkler system kick on in the middle of the night, when it had rained earlier in the day. He wished that his sprinklers were a bit smarter, so he decided to give the system an upgrade.

Rather than pay hundreds of dollars for a more sophisticated automation system, he spent about $45 on supplies and scrounged together some items he had sitting around the house to make a rain-sensing module of his own.

The resulting project, Pysprinklers, uses Python along with a handful of components to better manage his water usage. He got his hands on a cheap rain gauge, and modified it with a game controller and a set of magnetic surface contacts. If there has been a significant amount of rain in the last 24 hours, his system will prevent the sprinklers from turning on. Additionally, if there is rain in the forecast, the sprinklers will be delayed a bit to see if rain makes its way into the area.

We’re all for saving money (and water), so we think [Jashua’s] system looks great, especially because he ended up using a handful of things he already had on hand.

Whole House Battery Backup Used For Lower Power Bills

November 17, 2011 by Mike Szczys 78 Comments

[Photonicinduction] has an impressive battery backup installation that powers his whole house. Unlike a standalone emergency generator which would require you to hook up all of the device you want to run, this setup sits in between the power meter and the breaker box, ready to step in when needed.

But get this, he’s not just using it as a backup system. It kicks in during the day to run everything including two freezers, a refrigerator, his lights, television, and computers. That’s because the price per kilowatt-hour is quite a bit higher during the day than at night. So after 10:30pm the system patches his house back into the grid and charges the batteries for use the next day.

What you see here is just a portion of his system. The control board is not pictured but is very impressive, including a network of relays which are used as a fail-safe system so that there are no conflicts between mains and the battery system. Check out his 15-minute walk through of the system after the break. Continue reading “Whole House Battery Backup Used For Lower Power Bills” →

Spaduino Heats Up A Used Hot-tub

November 14, 2011 by Mike Szczys 38 Comments

[Ryan] and the roomies decided that a hot tub was just what they needed to spice up the place. They hit Craig’s List and found one for the right price. After acquisition and setup they were pleased to find that the jets and pump worked great. But you’re not going to want to stick as much as your big toe into this ice-cold cryogenics experiment. Some poking around in the control system exposed the dead relays which are responsible for switching the heater. Instead of swapping the parts, [Ryan] began building a control system that will replace the twenty-year-old original.

The heating element still works, but it’s rated at 5.5 kW and here’s no way to automatically switch it on and off. [Ryan] found a 60 Amp solid state relay which can handle the load, and plays nicely with his Arduino. Initial tests got the tub up and running again. Obviously you want the tub to maintain temperature and so a thermistor was added to take readings from the heater core. There’s also a potentiometer to adjust the temperature, and an LCD screen to show the current settings. But [Ryan] hopes to add more features over time, like incorporating jet control, and adding wireless communications via an Xbee module.

Chicken Light Keeps Up Egg Production

November 13, 2011 by Mike Szczys 10 Comments

It turns out that as the days get shorter, chickens lay fewer eggs. But you can trick them into keep up production using artificial light. [Jpitz31] decided to build his own timed coop light to bridge the gap until the days of plentiful sunlight return.

He already had an LED camping light to use, but needed to find a way to power it and to switch it on and off on a schedule. He chose an ATmega328 for the latter, as he had a bunch of extras sitting around. As for power, there isn’t AC available where the coop is, so he opted for a 12V lead-acid battery with hopes of adding solar charging features in the future.

Switching is handled by a relay, with accurate time kept by a DS1307 real-time clock (it’s the red PCB seen above). Everything fits nicely on the board, and we have a couple of feature suggestions for future improvements. The linear regulators will eat up some extra power so moving to a switching regulator will help save juice. Also, it would be very easy to add a light sensor so that the light will only be on when the ambient light drops to a preset level. This way he won’t need to mess with the schedule as the length of the days change.