clock hacks

924 Articles

Using A/C Frequency As A Clock Signal

April 30, 2010 by 31 Comments

A while back we saw a logic clock that used the alternating current frequency from the power grid to keep time. We asked for information on your projects that use this method and we got a lot of comments and tips. Today we’re sharing [Doug Jackson’s] method which he used in his word clock.

The schematic above is from that project and we’ve outlined the important part in green. [Doug] pulls a signal from the 9V AC power before it hits the bridge rectifier, using a 100K resistor and a zener diode to protect the microcontroller pin. The code for that project comes as a hex file but he sent us the C code pertaining to this timing circuit. It’s written for PIC but you’ll have no trouble adapting it to other microcontroller families. Take a look after the break.

Continue reading “Using A/C Frequency As A Clock Signal” →

IEE Clock

April 27, 2010 by 21 Comments

The IEE clock looks somewhat un remarkable at first glance. Upon closer inspection though, you’ll find out that there are 12 light bulbs crammed in there for each digit. The bulbs sit behind a curved lens with the numerals on it. When the appropriate one is lit, it projects the number on the front of the clock. While it isn’t new, it is certainly new to us. It is also interesting that you set the time by rotating the little dial on the top right. While it may be easier to set the time that way, it seems that it would be prone to getting nudged on accident.

[via the Hackaday Flickr pool]

Clock Hides Time Until You’re In Close Proximity

April 15, 2010 by 10 Comments

[Alan] is branching out beyond the Arduino with this clock. He’s still using the same code but built this board around an ATmega328 and the components he needed, saving his Arduino board for further development. The concept uses a character display housed in an old iPod Touch case. The build relies on an infrared sensor to actuate the LCD backlight. The closer your hand is the brighter the light.

The Maxim DS3232 RTC chip keeps time in this application. We’ve seen this little marvel used before, popular because it uses temperature compensation to maintain accuracy. If you’re interested in this part, check out the library file that [Alan] wrote for it.

Logic Clock Without An On-board Oscillator

April 7, 2010 by 58 Comments

[Lucassiglo21] developed this logic clock without using a crystal oscillator or a resonator. Instead, he’s letting the incoming electricity keep the time for him. The supply is AC at 50 Hz so he’s using some 4017 decade dividers to reduce that down to a 1 Hz signal. From there it keeps track of the ticks just like the last digital logic clock we saw.

If you’ve used AC line frequency as the clock source in your project we’d like to hear about it. Send us a tip and make sure your writeup includes a schematic. We’re especially interested to see if anyone has a good way of using this method with inexpensive microcontrollers.

Clock Sans-microcontroller

April 3, 2010 by 20 Comments

This clock requires no microcontroller. It’s actually a digital logic counter that functions as a timepiece. [BlackCow] used six decade counters to track seconds, minutes, and hours. The output is displayed on four 7-segment digits using BCD-7-segment decoders that you can learn about in our binary encoded decimal post. The actual timekeeping is done by a quartz clock circuit he pulled from a Mickey Mouse clock. This would be a perfect circuit to build in a digital logic simulator, just follow the schematic and learn as you go.

POV Clock Inside Acrylic Block

March 20, 2010 by 25 Comments

This gorgeous persistence of vision clock was built a couple years back by [mb1988]. The housing is made of acrylic with a hard drive motor mounted in the center of the back panel to spin a PCB. The two-sided circuit board is home-made and includes a battery for power, ATmega32 for the brain, 32 LEDs, four display drivers, and a real time clock module. The spinning hard drive motor is nearly silent and already has threaded mounting holes on it. [mb1988] uses an optoelectric sensor to sync the display with the rate of rotation. The forum post includes download for the code and hardware details. Don’t miss the demonstration after the break.

Continue reading “POV Clock Inside Acrylic Block” →

Pure TTL Based Clock

March 16, 2010 by 28 Comments

We’ll just say, [Kenneth] really likes clocks. His most recent is a pure 7400 series TTL based one, ie no microcontroller as seen in the past, here, here, and here. The signal starts out as a typical 32,768 crystal divided down to the necessary 1Hz, which is then divided again appropriately to provide hours and minutes.

As far as TTL clocks go, this is nothing too original; until it comes to his creative button interface. By using a not as sexy as it sounds multivibrator, he can produce a clean square wave instead of the figity signals produced from buttons to advance and set the time. Like always, he also provides us with a thorough breakdown of his clock, after the jump. Continue reading “Pure TTL Based Clock” →