Build a POV Death Star, you will

Building a Persistence of Vision globe is pretty awesome, but overlaying a Death Star pattern on the display takes it to the next level of geekery. Like us, [Jason] has wanted to build one of these for a long time. His success pushes us one step closer to taking the plunge and we hope it will inspire you to give it a shot too.

As he mentions in the beginning of his write up, the mechanical bits of these displays are really where the problems lie. Specifically, you need to find a way to transfer power to the spinning display. In this case use went with some DC motor brushes. These are replacement parts through which he drilled a hole to accept the metal axles on top and bottom. We hadn’t seen this technique before, but since motor brush replacements are easy to find and only cost a few bucks we’d say it’s a great idea.

The 24 blue LEDs that make up the display are all on one side of the PCB. They’re driven by an ATmega328 running the Arduino bootloader. [Jason] uses an FTDI adapter to program the chip. Don’t miss the video embedded after the break.

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Toothbrush timer

This toothbrush holder will make sure you’re brushing your pearly whites for an appropriate length of time. The three cups serves as tootbrush storage, and detect when one has been removed. Once you start brushing your teeth the lights on the front and bell in the back count down the process automatically.

The counting sequence starts when a weight sensor in the base detects a change caused by picking up a toothbrush. The ATmega328 — which is programmed with Arduino-style code — then turns on all of the incandescent lamps mounted on the front portion of the base. Each of these are switched with a 2N3904 transistor in order to sink enough current for the bulb. As a two-minute timer decrements, the bulbs are extinguished one by one. But there is also an auditory feedback mechanism. On the back of the base is a small bell. A hammer on a servo strikes the bell every 30 seconds to let you know how you’re doing. The entire thing is driven by an internal Li-ion battery which lasts about three weeks between charges. Don’t miss the demo video found after the break.

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Adding a heart rate monitor to your exercise equipment

This is the readout which [Remick] added to his stationary bicycle. It displays heart rate, calories burned, and a few other items to help motivate his workout routine.

Back when he was ordering a TI Chronos watch he also picked up a heart rate chest strap and receiver. The receiver can be read using a UART, making it easy to interface with the ATmega328 which drives the system. The screen is a graphic LCD, which gave him a lot of control on how to organize the displayed data. Three buttons on the side operate the menu system into which a user can enter sex, age, and weight information. This is used to calculate the calories burned and the percentage of maximum heart rate. The three readouts to the right are for time spent in each workout zone (fat burning, fitness, or performance). The final product looks great because of the PCB he etched and the case he housed it in.

Taking a moon light from grayscale to full color

[Terry Miller] picked up a moon light on the cheap. All it does is light up some white LEDs to simulate moon phases after sensing nightfall via an LDR. He figured he could do better and set out to replace the electronics with a more colorful offering.

He chose to use an ATmega328 because he already had it on hand. The chip drives a series of RGB LEDs in a multiplex arrangement. To protect the I/O pins (and drive the LEDs at their target current) he is using a set of high and low side MOSFETs. Rather than rely on the light sensor to switch on the lamp he decided to add an IR receiver. In the video after the break you can see that this lets him cycle through colors and effects, in addition to switching the lamp on and off with a remote control.

With the enclosure put back together he is still able to reprogram the chip thanks to a serial header included in the design. The device is battery operated and the life estimates are included in his write-up.

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Red Bull Creation hardware (Bullduino) arrives

The Bullduino’s are starting to arrive. When [Arclight] received his in the mail the first thing he did was to share the hardware details. Of course this is the hardware that participants in the Red Bull Creation contest will be receiving ahead of this year’s contest.

The board is an ATmega328 Arduino clone. Instead of an FTDI chip for USB this one is sporting an ATmega8u2. That’s not too much of a surprise as it should translate to a cost savings. [Arclight] reports that the stock firmware flashes a message in Morse code. It seems the Harford HackerSpace got their Bullduino several days ago and already decoded the message. It reads:

“Wouldn’t lou prefer a good game of chess?”

The guys that did the decoding speculate that this could be a type as ‘l’ and ‘y’ are inversions of each other in Morse code; or it could be some kind of clue. At any rate, if you want to do some disassembly and see if there’s anything lurking in the firmware, [Arclight] posted FLASH and EEPROM dumps from both ATmega chips along with his article.

New and improved Potentar

We like what we’re seeing and hearing with [Dorian Damon’s] newest version of the Potentar. This is revision 2.0 of the instrument we saw in a December links post. He calls it the Potentar, since it uses a linear potentiometer in a way similar to how the frets on a guitar work (Potentiometer + Guitar = Potentar).

The first thing you should notice is the case upgrade. The original used what looked like unfinished scrap wood, but finished wood of this case really makes the thing look like a traditional instrument. With this design he loses the Arduino in favor of a standalone ATmega328 chip. You’ll notice knobs and a switch on the face of the body. This allows for selecting a couple different kinds of scales and turning the power off. The linear potentiometer and sewing machine button are the same as before. After the break you can catch his description and a quick performance thanks to the audio jack for patching it into an amp.

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Motion sensitive RGB lamp can standby for 3 years

Ooooh, nice enclosure! This is a little motion sensing lamp which [Krazatchu] built a few years back as a Mother’s Day gift. The PIR sensor is easy enough to see as the white dome on the front of the case. But look closely below that and you’ll see the LDR which it uses to keep the thing asleep during the day. This is intended to save on batteries but the original version still ate through them like crazy. This year he gutted it and worked out a much more power-friendly design.

He moved to a TLC1079 OpAmp which greatly reduced power consumption when reading from the PIR sensor. The microcontroller was also upgraded from an ATtiny13 to an ATmega328, making the new version Arduino compatible. It puts itself to sleep and keeps the lights out during the day, drawing just 0.08 mA. When driving the RGB LED the lamp pulls about 50 mA. That should still last a while on three AA batteries but we’d still recommend using rechargeables.

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