Joule Thief Steals Power for a Clock

A common project among electronics tinkerers is the joule thief, a self-oscillating circuit that can “steal” the remaining energy in a battery after the voltage has dropped so low that most devices would stop working. Typically the circuit powers an LED until almost all of the energy is extracted from the battery, but [Lionel Sears] has created a specialized joule theif that uses the “extra” energy to power a clock.

The circuit uses four coils instead of the usual two to extract energy from the battery. The circuit charges a large capacitor which provides the higher current pulses needed to drive the clock’s mechanism. It can power the clock from a single AA battery, and will run until the voltage on the battery is only 0.5 volts.

Normally the clock would stop running well before the voltage drops this low, despite the fact that there’s still a little chemical energy left in the batteries. The circuit can drive the clock for an extended time with a new battery, or could use old “dead” batteries to run the clock for a brief time while the final little bit of energy is drawn from them. If you’re so inclined, you could even use hot and cold water with a joule thief to run your clock! Thanks to [Steven] for the tip.

Exposed Clock is Flippin’ Cool

Some hacks are triumphs of cleverness, others…are just cool. [Super Cameraman’s] exposed retro flip clock tends toward the latter half of that spectrum—it may not be the most complex, but we’re relieved that for once there isn’t an Arduino crammed into the back of it.

You can buy pared down, exposed flip clocks at museums for an arm and a leg, or you can trudge through eBay and local thrift shops until you come across a cheapo clock radio. [Super Cameraman’s] clock cost him exactly $2, and is split into two sections: a clock side and a radio side. Prying off the knobs and popping open the case reveals all the shiny mechanisms and electronics, most of which he trashed. The radio and even the transformer were removed, leaving only the flip clock, which he re-wired directly to the plug—it seems these types of clocks run straight off 120VAC. Check out the video below.

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World’s Largest “Nixie” Clock at World Maker Faire

World Maker Faire was host to some incredible projects. Among the favorites was Nixie Rex [YouTube Link]. Nixie Rex is actually a Panaplex display, since it’s glow comes from 7 planer segments rather than 10 stacked wire digits. One thing that can’t be contested is the fact that Rex is BIG. Each digit is nearly 18 inches tall!

Nixie Rex was created by [Wayne Strattman]. Through his company Strattman Design, [Wayne] supplies lighting effects such as plasma globes and lightning tubes to the museums and corporations. Nixie Rex’s high voltage drive electronics were created by [Walker Chan], a PHD student at MIT. Believe it tor not the entire clock runs on an ATmega328P based Arduino. The digits are daisy chained from the arduino using common Ethernet cables and RJ45 connectors. A Sparkfun DS1307 based real-time clock module ensures the Arduino keeps accurate time.

[Wayne] and Rex were located in “The Dark Room” at Maker Faire, home to many LED and low light projects. The dim lighting certainly helped with the aesthetics, but it did make getting good photos of the clock difficult. Long time Hackaday tipster [Parker] graciously provided us with a size reference up above.

Click past the break to see a closeup of that awesome cathode glow, and a video of the Nixie Rex  in action.

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Topsy Turvy Clock Tells Confusing Time

Looking for a new clock but hate the fact that all the numbers are always in the correct order? Look no further than [Andy]’s topsy turvy clock which correctly tells time despite the fact that the numbers on the face of the clock are in random positions.

At first glance, the clock looks fairly normal despite the mixed-up numerals. Upon closer inspection, the clock is much more than it appears to be. A battery backed real-time clock keeps track of time, and a microcontroller turns the hands of the clock to where they need to be. The clock uses optical sensors to make sure the hands are in the correct starting position when it is first powered on.

Check out the video below for a better illustration of what the clock looks like when in operation. The hour hand is always pointing at the correct hour, and the minute hand starts every five minutes at the number it would have started at on a normal clock, i.e. at 1:15 the hour hand will point at “one” and the minute hand will point at “three”.

We love this very interesting and unique take. It was inspired by a few other clocks, including a version of the infamous Vetinari “random tick” clock which will drive you crazy in a different way.

[Sprite_TM] Puts Linux in a Clock Radio

[Sprite] needs an alarm clock to wake up in the morning, and although his phone has an infinitely programmable alarm clock, his ancient Phillips AJ-3040 has never failed him. It’s served him well for 15 years, and there’s no reason to throw it out. Upgrading it was the only way, with OLED displays and Linux systems inside this cheap box of consumer electronics.

After opening up the radio, [Sprite] found two boards. The first was the radio PCB, and the existing board could be slightly modified with a switch to input another audio source. The clock PCB was built around an old chip that used mains frequency as the time base. This was torn out of the enclosure along with the old multiplexed LCD.

A new display and brain for the clock was needed, and [Sprite] reached into his parts drawer and pulled out an old 288×48 pixel OLED display. When shining though a bit of translucent red plastic, it’s can be a reasonable facsimile of the old LEDs. The brains of the clock would be a Carambola Linux module. After writing a kernel module for the OLED, [Sprite] had a fully functional Linux computer that would fit inside a clock radio.

After having a board fabbed with the power supplies, I2C expanders, USB stereo DAC, and SPI port for the OLED, [Sprite] had a clock radio that booted Linux on an OLED screen. In the video below, [Sprite] walks through the functions of the clock, including setting one of the many alarms, streaming audio from the Internet, and changing the font of the display. There’s also a web UI for the clock that allows alarms to be set remotely – from a phone, even, if [Sprite] is so inclined.

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Persistence of Vision Clock on a Propeller

If you have a spare DC motor, a PIC16F84A microcontroller, and a lot of patience, then [Jon] has a great guide for building a persistence of vision clock that is sure to brighten up any room. For those who are unfamiliar with this type of clock, the principle is simple: a “propeller” with LEDs spins, and at just the right moment the LEDs turn on and display the time.

We’ve featured persistence of vision projects before (many times), and have even featured [Jon]’s older clocks, but the thing that makes this POV clock different is the detail of the project log. [Jon] wasn’t satisfied with the documentation of existing projects, and went through great pains to write up absolutely everything about his clock. The project log goes through four major versions of the hardware and goes into great depth about the software as well, making it easy for anyone to recreate this robust clock.

As for the clock itself, the final revision of the hardware has a PCB for all of the components, and uses a PC fan motor to spin the propeller. Power delivery eliminates slip rings or brushes in favor of wireless power transfer, which is an impressive feat on its own. Indeed, the quality of the clock is only surpassed by the extreme level of detail!

Master Clock Keeps Time for All Other Clocks

[Brett] just finished construction and long-term testing of this extremely accurate timepiece. It keeps such great time by periodically syncing with the atomic clock in Mainflingen, Germany.

The core of the project is an ATMega328 which uses the new DCF77 library for decoding the signal broadcast by an atomic clock. The libraries written by Udo Klein significantly increase the noise tolerance of the device reading the signal, but they will not work with any project that use a resonator rather than a crystal.

In the event of a complete signal loss from the atomic clock, the micro driving the clock also has a backup crystal that can keep the clock running to an accuracy of within 1 second per day. The clock can drive slave clocks as well, using pulses with various timings depending on what [Brett] needs them to do. The display is no slouch either: six seven-segment displays show the time and an LCD panel reads out data about the clock. It even has chimes for the hour and quarter hour, and is full of many other features to boot!

One of the most annoying things about timekeeping is daylight savings time corrections, and this clock handles that with a manual switch. This can truly take care of all of your timekeeping needs!