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Friday, November 14, 2014

Flashback VCR Cat Feeder from MAKE Volume 03

One of the most iconic projects from the pages of MAKE is the VCR Cat Feeder from MAKE Volume 03 (2005). It’s depressing to think of all the discarded VCRs in the world, but author James Larsson gave us a creative and useful way to repurpose this hunk of outdated machinery. Cats are wonderfully independent creatures for the most part, so when you’re leaving on a weekend trip, this programmable cat feeder is the ticket for keeping your feline companion well fed. Basically, you hijack a motor from inside the VCR, slow down its rotation with a gearbox, add an auger system with attached food container, and use the VCR’s timer-recording system to dispense scheduled meals. Some things never get old, like watching people’s facial expressions when you say “VCR Cat Feeder.”
Check out the full project on Make: Projects, and also watch this clip of John Park demoing the feeder on Make: television:

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Saturday, November 8, 2014

Sounds From The Old West

This circuit shows how far integration can be taken: IC1, a Type HT82207 from Holtek does virtually everything. Only a (small) loudspeaker and the necessary selectors need to be added. The standard 18-pin Type HT82207 is an integrated sound generator, producing sounds typical of the Old West. The various sounds are selected by S1–S6 as listed below. In the quiescent state, the circuit draws a current not exceeding 1 µA.

    S1 – bugle
    S2 – neighing
    S3 – sound of hooves
    S4 – pistol shot
    S5 – crack of a rifle
    S6 – cannon fire

Circuit diagram:

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Friday, June 6, 2014

New MEMS Device Generates More Energy From Small Vibrations

Researchers at MIT have designed a novel device the size of a U.S. quarter that harvests energy from low-frequency vibrations, such as those that might be felt along a pipeline or bridge. The tiny energy harvester — known technically as a microelectromechanical system, or MEMS — picks up a wider range of vibrations than current designs, and is able to generate 100 times the power of devices of similar size.

To harvest electricity from environmental vibrations, researchers have typically looked to piezoelectric materials, or PZT, such as quartz and other crystals. Various designs are based on a small microchip with layers of PZT glued to the top of a tiny cantilever beam. As the chip is exposed to vibrations, the beam moves up and down like a wobbly diving board, bending and stressing the PZT layers.

The stressed material builds up an electric charge, which can be picked up by arrays of tiny electrodes. However, the beam itself has a resonant frequency and outside of this frequency, the beam’s response drops off, along with the amount of power that can be generated. [Link]

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