Forum user Cyclist recently built a free pendulum clock.

The cool thing about a free pendulum is that it has no mechanical linkage, escapement mechanism, or direct mechanical power to keep it going.

A small magnet on the bottom of the pendulum induces a voltage on a coil mounted beneath as it swings past. The voltage is detected by Teensy’s a/d converter and triggers a propulsion pulse applied to the coil from a digital output pin. This gives the pendulum a tiny nudge to keep it going. The pendulum defies the senses, swinging in eerie silence.

Cyclist reported that the accuracy is all about the pendulum.  He had it going for about a week and it was running slow by a consistent 1 second per day. He’s working on trying to refine the pendulum  and pivot design for easier, finer adjustment.

Nick Metchalfe built his own audio spectrum analyzer that produces a detailed picture of what you are listing to in real time, showing the changing spectrum of live input signals up to 16 kHz.  By using 2 16×32 LED matrixes, the spectrum displays 64 bands.

This video show the spectrum analyzer in action.

Nick says that the Teensy Audio Library is at the heart of the design, providing audio capture and high resolution FFT routines. Audio frequency data is scaled and binned into logarithmic frequency response groupings and is plotted using a custom fast display driver into a spectrum that approximates the human auditory response for a balanced visual aesthetic.

Nick says that the Teensy Audio Library is at the heart of the design, providing audio capture and high resolution FFT routines. Audio frequency data is scaled and binned into logarithmic frequency response groupings and is plotted using a custom fast display driver into a spectrum that approximates the human auditory response for a balanced visual aesthetic.

He’s posted his spectrum analyzer code on GitHub.

Jeremy Gilbert made an awesome clicky toy.  The goal of the project was to create a toy that is fun to use, be tactile, light up, and make fun and satisfying noises.

After looking at different options to get the right “clicky-ness”, a 5V relay was used.  Jeremy discovered that you get get louder clicks if you overdrive the voltage.  While this probably isn’t so good for the relay, he felt that since the actual duty cycle is so short it was worth the risk.

The clicky box of awesomeness is  field programmable so that when new suggestions come up during user acceptance testing (performed by his 3-year old daughter) they can be implemented right away.

The write up on Jeremy’s Hackaday project offers a good narrative of how he approached the challenge of getting the right clicky sound and feel.

 

Ben Forta made a giant menorah, with spinning dreidels, to celebrate Chanukah.

This impressive display is over 20 feet wide,  6 feet high, using over 3,500 NeoPixels with animated lighting sequences.

This tweet from Ben has a little more info.  Hopefully he’ll have time to share more photos & video soon.

Keith Baxter made a hand held MIDI keyboard called The Kyub.  This device using capacitive sensing and has an internal accelerometer for controlling the volume.

This video from their Kickstarter campaign gives a good overview and explanation of how the Kyub works.

This is a pretty cool video demoing the Kyub configured as a set of drum pads.

The software and details about how to build and use the Kyub are available on the Kyub website.

Eli Fatsi made his own Iron Man-esque shoulder mounted Nerf gun that can be controlled by a Pebble watch.

With this cool project you could be like Iron Man and destroy your enemies by simply touching a controller on your wrist.

The code for the project can be found on GitHub.

Elliot Carter published a tutorial on making a photoresistor-based tachometer.

The project came about when he needed to test the top speed of a stepper motor.  After putting it together the project became an important diagnostic tool for a larger project – not only does it test the top speed of stepper motors but it also works as a tool to verify code.

The tachometer measures rotational speed using only simple light sensor with an op-amp comparator circuit.  While many mechanical engineers might cringe at the thought of an op-amp, Elliot’s team found a tutorial that explained them well.

Some of the features include:

• Custom tuning mode allows 128 notes as per the MIDI standard (12 notes [C, C#, D, D#, E, F, F#, G, G#, A, A#, B] across 11 octaves for C-G and 10 octaves for G#-B)
• Full soprano ukulele fretboard (12 frets)
• Four lasers as strings
• Virtual capo can be placed along any of the 12 frets
• Although this is in the shape of a ukulele, the computer software determines the final sound, so the physical instrument could end up sounding like whatever instrument you desire
• Note velocity can be customized from 0 to 127 and is displayed on the LCD screen