Enjoying The Sunrise Every Single Day


[Andy] wanted to take a few at sunrise, but waking up before sunrise has obvious problems associated with it. Instead, he built a device that calculates the local sunrise time, snaps a picture, and goes to sleep until the next morning.

The camera used for the project was an old Canon point and shoot, chosen for the ability to load CHDK firmware. Other electronics included an Arduino pro mini, a LiPo battery and charger board, real time clock, and an old Nokia LCD for the user interface.

There’s quite a bit of code that goes into figuring out when the sun will rise each day, but once that’s figured out, all [Andy] has to do is take the camera somewhere pretty, point it East, and record a few days worth of sunrises. When put into a ‘game camera’ enclosure, its rugged enough to stand up to everything except a thief, and has enough battery power for a few weeks worth of sunrises.

Video demonstrating the local sunrise time below.

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Hard Drive Clock is Simple and Elegant

Binary hard drive clock

[Aaron] has been wanting to build his own binary desk clock for a while now. This was his first clock project, so he decided to keep it simple and have it simply display the time. No alarms, bells, or whistles.

The electronics are relatively simple. [Aaron] decided to use on of the ATMega328 chips he had lying around that already had the Arduino boot loader burned into them. He first built his own Arduino board on a breadboard and then re-built it on a piece of protoboard as a more permanent solution. The Arduino gets the time from a real-time clock (RTC) module and then displays it using an array of blue and green LED’s. The whole thing is powered using a spare 9V wall wort power supply.

[Aaron] chose to use the DS1307 RTC module to keep time. This will ensure that the time is kept accurately over along period of time. The RTC module has its own built-in battery, which means that if [Aaron's] clock should ever lose power the clock will still remember the time. The RTC battery can theoretically last for up to ten years.

[Aaron] got creative for his clock enclosure, upcycling an old hard drive. All of the hard drive guts were removed and replaced with his own electronics. The front cover had 13 holes drilled out for the LED’s. There are six green LED’s to display the hour, and seven blue LED’s for the minute. The LED’s were wired up as common cathode. Since the hard drive cover is conductive, [Aaron] covered both sides of his circuit board with electrical tape and hot glue to prevent any short circuits. The end result is an elegant binary clock that any geek would be proud of.

Pokewithastick, an Arduino programmable web-logger/server

[Stewart] tipped us about his very nice project: pokewithastick. It is an Arduino compatible board (hardware, not footprint) based on the ATMEGA1284P which can be programmed to collect and post data to internet logging sites such as Thingspeak or Xively.

As you can see in the picture above, it has a small 50x37mm footprint (roughly 2″x1.5″). The pokewithastick is composed of an Wiz820 Ethernet module, a micro-SD card slot, 2 serial ports, one battery backed Real Time Clock (RTC), one radio connector (for the usual nRF24L01 2.4GHz radio), one power & user LED and finally a reset button. There are two power rails on the board which can be split (5v + 3.3V) or combined (3.3v only) which may allow you to connect Arduino shields to it. You can program the board using the standard 6-pin header or via a serial programmer if an appropriate (Arduino) bootloader is installed.

The project is open hardware, has been designed using Kicad and all the files can be downloaded as a zip file.

Volt meter clock also displays the temperature

[IronJungle] got around to putting together every tinkerers favorite project: a clock with a strange way of displaying the time. For his clock, [Jungle] took a trio of voltmeters and turned them into a clock that displays the current hour, minute, and second on custom paper dials.

[IronJungle] connected a PIC 14M2 microcontroller to a DS1307 real time clock to keep track of the current time. As for display, [Jungle] took a trio of volt meters and wired them in to the PWM outputs on his PIC. With this, he was able to precisely control the position of the needle in the meter, and thus display the time.

In addition to displaying the time, [IronJungle] added a small temperature sensor to his build. By pressing a button below the seconds display, the clock is able to display the current temperature in Fahrenheit, Celsius, and Kelvin.

After the break you can check out a time-lapse video of [IronJungle]‘s voltmeter clock going through the hours.

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Auto-locking pet door ensures that your outdoor kitty obeys its curfew


If you’ve got a pet that roams freely in and out of your house, you may find yourself wanting to more closely regulate how they come and go. [tareker] was looking to keep his cat indoors at night when dangerous animals might be lurking in the neighborhood, but he didn’t want it to become a hassle.

He already had locking pet door on hand, which he hacked to regulate the egress and ingress of his cat automatically. He installed a pair of reed switches to determine if the door had been opened outwards (cat leaving) or inwards (cat returning), keeping track of the state using an Arduino Nano. A servo motor attached to the door’s frame locks the door whenever it detects the cat is safely inside after nightfall.

While he also added an RGB LED to reflect the status of the door, he’s considering connecting it to the Internet so that he can control and check the door from wherever he might be at the moment.

Building your own real time clock


Like many electronics hobbyists, [Pete] found that he had an overwhelming desire to build a clock for himself. He didn’t want to stick a discrete real time clock IC into a box and call it a day, so he opted to construct his own around a microcontroller instead.

After researching the specs on a few RTC ICs, he defined some accuracy requirements for his clock, and got to building. He started out using a 32,768 Hz watch crystal, but found that the accuracy was off by about 46 ppm after only 24 hours of use. That fell well beyond his self-imposed +/- 3 ppm tolerance goal, so he purchased an oscillator with about 500 times the resolution of his previous crystal.

After writing a handful of code to ensure that the clock remains stable, he calculated that his accuracy should be about 0.18 ppm – well within his acceptable tolerance range.

[Pete] says that this is just the first part of his clock construction, and that future revisions should include plenty of additional functionality, so keep an eye out for updates.

Too much time, not enough pressure


[Audin] got a hold of a pressure gauge and decided to turn it into a clock. We were under the impression that these types of gauges were filled with oil but he didn’t detail cleaning it up for his purposes. Once he gained access to the guts he replaced them with a stepper motor. The motor connects to an Arduino with the help of a Darlington array for handling the large load. [Audin's] plans include using a real time clock (on order) and moving to an AVR ATmega8 microprocessor once the prototyping is finished. In the mean time, he has posted the code used in his current prototype.

Stay with us past the page break for some video of this in action. He’s got the needle dialed in for very precise movement and has coded a “jitter” effect as well. We’re not sure this would be the most convenient clock, but we’d love to affix it to our kitchen stove for a gnarly looking timer. [Audin] acquired the gauge at his local Habitat for Humanity ReStore, a place we’ve used many times to source reclaimed and unused items of all kinds for our projects.

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