Prototyping The New Office Clock

June 1, 2011 by Mike Szczys 10 Comments

[Damage] was tapped to build a new clock to hang on the wall at the office. He got a hold of some 6.5 inch seven segment displays for the hours and minutes, as well as some 4.5 inch modules for the date and month. Rather than jump right in with the large hardware (especially because he’s waiting for the PCB order to arrive) he built this prototype with more commonly sized displays.

His build is Arduino powered. In the video after the break he mentions the temperature compensated crystal oscillator that keeps the time. We’d wager that’s the DS3234 based RTC module that Sparkfun sells. This is the same chip family as the Chronodot and it was our choice for the Ping Pong Clock.

The finished clock will hang high on wall, out of reach when you need to set the time. This shouldn’t need to be done much – if ever – since that RTC includes a backup battery. But [Damage] took the time to develop a remote programming device anyway. Using another Arduino, an LCD display, and an Xbee pair he whipped up a remote that can be used to navigate and change the main unit’s settings.

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Building Your Own Real Time Clock

May 23, 2011 by Mike Nathan 20 Comments

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.

It’s Like… I Can Tell The Time Just By The Color, Man

May 22, 2011 by Mike Szczys 15 Comments

[Alex] has reduced the resolution of his timepiece as a trade-off for speedy-readability. At least that’s what he claims when describing his color-changing clock. It uses a ShiftBrite to slowly alter the hue of the clock based on the current time. The concept is interesting: 12:00 starts off at white and slowly fades to green at 3:00, blue at 6:00, red at 9:00, and back to white by 12:00 to start the process over again. He has gotten to the point where he can get the time within about 15 minutes just with a quick look. But he did need to spend a few days acquiring the skill by having the color clock sit next to a traditional digital clock.

The build is pretty simple and we’d bet you already have what you need to make your own. [Alex] is really just proving a concept by using the ShiftBrite and an mBed, there’s no precision RTC involved here. So grab your microcontroller of choice, and an RGB LED of your own and see if you can’t recreate his build.

Of course you could always choose to build a color-based timepiece that’s even harder to read.

An Alarm For Every Day Of The Week

May 19, 2011 by Mike Szczys 27 Comments

If you don’t have a 9-to-5 type of job you might find yourself constantly resetting your alarm clock as your calendar commitments change. [Lucas] finally got fed up with the nightly ritual and decided to build his own alarm clock which has unique settings for each day of the week (translated).

The display itself is an LM044L 20×4 character display. This provides a viewing area that is about 3″x1″ and since it’s an HD44780 compliant LCD screen, writing data to it takes very little effort (and RAM) compared to a graphic LCD. A PIC 18F2550 drives the device, taking input from a half-dozen buttons, driving the display, and turning on the enclosed buzzer when it’s time to get up. There’s a backup battery which will keep the settings when power is lost. The daily alarms, current time, and back light brightness can all be adjusted from the four screens that make up the settings menus. The only thing that it’s missing is a precision timekeeper, but that should be easy to add either by measuring the frequency of the mains or by using an RTC chip.

Analog Projection Clock So Simple You Should Have Thought Of It

May 4, 2011 by Mike Szczys 29 Comments

The image you see above is the result of a simple analog projection clock. It shows the time on the ceiling. We have one in our bedroom but it’s a red digital display which we don’t think is nearly as fun as this clever hack. Grab a cheap analog clock, a mirror, and a white LED and you can build your own.

The mirror is going to reflect light from the LED onto a ceiling or other surface. It acts as the clock face. The tick marks for each hour were made by scratching the reflective material (often called the silvering) from the back of the mirror. A hole is drilled at the center of the class and the analog clock is mounted with its hands on the business side. The one problem with this setup is that since the light is being reflected, the clock will appear to run backwards. Not a problem, if you just reverse the polarity of the coil which moves the clockwork the projection will move in the expected clockwise direction.

[via Make]

DIY Sunrise Alarm Clock

May 4, 2011 by Mike Nathan 15 Comments

As a project for an embedded systems class, [Alan] recently built himself a sunrise-simulating alarm clock. You are probably familiar with these sorts of timepieces – they gradually light up the room to awaken the sleeping individual rather than jarring them awake with a buzzer or the radio. Since many commercial units with this feature are sold for $70 and up, his goal was to replicate the functionality at a fraction of the cost, using only open source components.

An Arm Cortex M3 processor runs the show, displaying the time via a pair of 8×8 LED matrix panels on the front of the device. The clock is programmed to gently wake up its user by simulating a sunrise over a period of 5, 15, 30, 45, or 60 minutes. If the user has not woken up before the sunrise simulation is complete, the clock resorts to a traditional piezo alarm to rouse the heavy sleeper.

The project is nicely done, and after looking at his bill of materials it seems to be far cheaper than many sunrise alarm clocks you will find in stores.

Egg Clock (it’s Egg-ceptional)

May 3, 2011 by Mike Szczys 9 Comments

Easter is over and with some plastic eggs still on hand, [Franspaco] was looking for something to do with them. He decided to use an egg as an enclosure for a digital clock.

You can see that the finished project uses just one 7 segment LED display to show the time. A scrolling number method is used to delineate each digit of the 24-hour time readout. The display will go blank, followed by two numbers for the hours, a dash as a separator, and finally two more digits for the minutes. A PICAXE microcontroller drives the clock, but for accuracy a DS1307 does the timekeeping.

[Franspaco] etched his own circuit board that is sized to fit perfectly, housing the two chips, an LED, and a programming header. The on-board LED blinks at 1 Hz, giving some inner glow to the plastic shell. He accomplished most of his goals, but was unable to fit the batteries inside of one egg, prompting the need for a tethered power-egg. If he moves to surface mount components for the next generation of this device we think he’ll have no problem fitting a small battery (like an A23) inside.