Mains Frequency Display

December 12, 2013 by James Hobson 45 Comments

[James] lives in the UK where the frequency of electricity is suppose to be 50Hz, but it tends to fluctuate based on supply and demand. He decided he wanted a display to track this.

Now, the National Grid Website shows a real-time graph of the last 60 minutes. But that’s way too easy. Time to bust out the soldering iron!

Armed with pencil and paper [James] scribbled down some ideas on how to count the frequency — he settled on counting 200 cycles, which means that at 50.000Hz, it would take exactly 4 seconds. The next problem was getting a timing source that was accurate enough for the job. An ATtiny84 wouldn’t do the trick (too inaccurate), nor would an external crystal (too expensive) — But a real-time clock? That’s the ticket! He’s using a DS3231 RTC chip, which at +/- 2ppm 32.768kHz is more than precise enough.

Some math, programming, and soldering later and the display is complete! He’s even added an up/down arrow to show the most recent trend of the electricity.

Nice one [James]! Last year [Ch00f] did a similar project, where he tore down a 194 discrete transistor clock kit to see how it worked — as an aside, he needed to know how accurate the 60Hz coming out of his wall was!

$50 Backyard Rollercoaster

December 8, 2013 by James Hobson 36 Comments

This is great. What happens when you bet a group of friends they can’t build a roller coaster in their backyard for under $50? They build one.

They built it almost entirely out of old forklift pallets, some wood from Home Depot, assorted nails and screws, some caster wheels and a folding seat from an old arena. It was built in just over 9 hours by three people. Once assembled they tested it with a 15lb cinder block — safety first right? The cinder block survived the ride, and by that logic, a 160lb+ person should be fine as well!

Well… they were right! To finish it up and get into the holiday spirit they also decked it out in Christmas lights and let the neighborhood kids use it all night. The total came to $49.27 from Home Depot for the wood and wheels.

Stick around after the break to see a .GIF of it in action!

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Raspi AC And Blinds Controller

December 7, 2013 by Marsh 10 Comments

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[Chris’s] bedroom has a unique setup with an air conditioning unit perched on the wall next to the top of the blinds that cover his window. Normally, to open the blinds he had to tug on a cord and operating the AC meant fiddling with a remote control. Not anymore. Now [Chris] has an all-in-one Raspberry Pi-based solution to drive both.

The build uses a stepper motor salvaged from a printer to directly drive the blinds, with a familiar-looking Easy Driver connecting it to the Pi. The motor spins the blinds’ mechanism either open or closed, though at a modest pace that’s slow enough to provide the needed torque. [Chris] added an IR diode plugged into the Pi that imitates the air conditioning unit’s remote control, and simply pointed it directly at the unit’s receiver. An inexpensive WiFi dongle gets the Pi onto the network, allowing [Chris] to interact via a custom web interface. The interface itself not only provides a couple of clickable buttons, but a cleverly-designed status image indicating the position of the blinds.

Make sure you see the video below for a demonstration and for more details on the build. This is one of the better examples of home automation devices we’ve seen recently, especially considering it actually fits the “autonomous” implications discussed in our Ask Hackaday post from a few months back—although a relatively simple automation, [Chris’s] interface does allow for operating both the blinds and the AC on a preselected schedule.

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Android And Arduino RF Outlet Selector

December 6, 2013 by Marsh 14 Comments

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Cyber Monday may be behind us, but there are always some hackable, inexpensive electronics to be had. [Stephen’s] wireless Android/Arduino outlet hack may be the perfect holiday project on the cheap, especially considering you can once again snag the right remote controlled outlets from Home Depot. This project is similar to other remote control outlet builds we’ve seen here, but for around $6 per outlet: a tough price to beat.

[Stephen] Frankenstein’d an inexpensive RF device from Amazon into his build, hooking the Arduino up to the 4 pins on the transmitter. The first step was to reverse engineer the communication for the outlet, which was accomplished through some down and dirty Arduino logic analyzing. The final circuit included a standard Arduino Ethernet shield, which [Stephen] hooked up to his router and configured to run as a web server. Most of the code was borrowed from the RC-Switch outlet project, but the protocols from that build are based on US standards and did not quite fit [Stephen’s] needs, so he turned to a similar Instructables project to work out the finer details.

Stick around after the break for a quick video demonstration, then check out another wireless outlet hack for inspiration.

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Crab-ble – A Table That Walks

December 4, 2013 by James Hobson 22 Comments

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Do you have a heavy kitchen table? Wish you could move it all by yourself? [Ekaggrat] set out to design one for this year’s Beijing Design Week back in September.

It’s based off of the awesome Strandbeest design by [Theo Jansen], and it looks great. [Ekaggrat] made several prototypes of the “Crab Table” out of ABS plastic, and was planning to make a full size one using bamboo rods, which were the theme of the design week. Unfortunately the team ran out of time and was not able to make the full scale model. The prototypes walk around all by themselves with geared DC motors, but the plan for the full size one was to simply be able to push it.

We’ve seen lots of walking tables before, but there’s just something about the mechanical beauty of this design that we love. It’d be heavy — but imagine it in chrome! Maybe just the plastic could be plated… Stick around after the break to see it scuttle about!

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Using Ultrasonic Sensors To Measure And Log Oil Tank Levels

December 4, 2013 by Mathieu Stephan 52 Comments

[Mike] lives in a temperate rainforest in Alaska (we figured from his website’s name) and uses a 570 gallon oil tank to supply his furnace. Until now, he had no way of knowing how much oil was left in the tank and what his daily usage was. As he didn’t find any commercial product that could do what he wanted, he designed his own solution. In his write-up, [Mike] started by listing all the different sensors he had considered to measure the oil level and finally opted for an ultrasonic sensor. In his opinion, this kind of sensor is the best compromise between cost, ease of use, range and precision for his application. The precise chosen model was the ping))) bought from our favorite auction website for around $2.5.

[Mike] built the custom enclosure that you can see in the picture above using PVC parts. Enclosed are the ultrasonic sensor, a temperature sensor and an LED indicating the power status. On the other side of the CAT5 cable can be found an Arduino compatible board with an XBee shield and a 9V battery. Using another XBee shield and its USB adapter board, [Mike] can now wirelessly access the tank oil level log from his computer.

Arduino-Powered Steampunk Steam Gauge

November 30, 2013 by Marsh 11 Comments

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[Murphy’s_Lawyer] had some empty space on the wall in his kitchen, so he decided to fill it with a whirring Steampunk gizmo: an Arduino-driven steam gauge.

The build began as an old 10″ Ashcroft pressure gauge sourced from eBay, which [Murphy’s_Lawyer] dissected to determine the state of its guts. Finding the gauge’s Bourdon tube intact, he got to work constructing a method of generating motion without the need for actual steam. The solution was to mount a continuous rotation servo between the tube and the case. The servo lacked the strength to flex the tube on its own, so [Murphy’s_Lawyer] fashioned a simple lever out of brass to help it along.

The electronics consist of an Arduino Uno and an accompanying homemade PCB. The code for the Uno generates random motion for twirling the servo, and three LEDs built into the face reflect values generated for speed, pause and run time. The final upgrade came in the form of a new dial face, which provides some updated text as well as a cutout square that lets you see the previously obscured gears in action. Check out the video below, then see another Steampunk overhaul: the Edwardian Laptop.

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