Follow the Bouncing Ball of Entropy

When [::vtol::] wants to generate random numbers he doesn’t simply type rand() into his Arduino IDE, no, he builds a piece of art. It all starts with a knob, presumably connected to a potentiometer, which sets a frequency. An Arduino UNO takes the reading and generates a tone for an upward-facing speaker. A tiny ball bounces on that speaker where it occasionally collides with a piezoelectric element. The intervals between collisions become our sufficiently random number.

The generated number travels up the Rube Goldberg-esque machine to an LCD mounted at the top where a word, corresponding to our generated number, is displayed. As long as the button is held, a tone will continue to sound and words will be generated so poetry pours forth.

If this take on beat poetry doesn’t suit you, the construction of the Ball-O-Bol has an aesthetic quality that’s eye-catching, whereas projects like his Tape-Head Robot That Listens to the Floor and 8-Bit Digital Photo Gun showed the electronic guts front and center with their own appeal.

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Pseudo-Random Flickering Jack-O-Lantern LED using ATtiny13

Pseudo_Random_Flicker_ATtiny13

It’s time to get those jack-o-lanterns twinkling for Halloween. If you don’t want to use candles or buy a jack-o-lantern light this Halloween you can do like [Johannes Bauer] and code your own pseudo-random flickering super bright LED. His wife wanted their pumpkin to be illuminated this year and he knew it would be easy to do with an Arduino, but that would be overkill for such a simple project. Plus, he doesn’t have an arduino. [Johannes] used very few components; 4 slightly depleted AA batteries, a super bright LED, 680 ohm resistor and a little custom code on an 8 pin ATtiny13. The circuit does work great for a pumpkin lantern but his video is more of a tutorial on coding linear congruential generator (LCG) for the 8 bit pseudo-random LED flickering.

The code is short and can be gleaned from the YouTube video. [Johannes] used avr-gcc to compile and has packaged his code and build scripts for download. The hex file can be flashed over to the chip using avrdude or AVR Studio. If you have any ATtiny13s lying around you should cobble this hack together just in time to emulate that real look of a pumpkin candle without the hassles and hazards of real flames.

If you want something with a lot more light that still has that candle like flicker then checkout “Flickering Pumpkin Lanterns” that used the signal from LED tea lights to power some 12 V lamps.

Follow along after the break to watch [Johannes Bauer’s] video.

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