Geek Stuff

Brooke Clarke 2013

Background
Theremin
Electronic Goldfish in a Bowl
Fireflies in a Jar
Butterfly on a string
Zendulum
Links

Background

There are some thing's I'm find interesting but that I'm not going to spend my life pursuing.

Theremin

The Theremin (Wiki)  is an electrical musical instrument played by using one hand to control the pitch and the other to control the volume.  Since both controls depend on the capacitance between the hand and instrument sensing antenna, any body movement other than the hand will be heard.  So you will notice that the performer is holding very still except for the hand movements. Pamelia Kurstin plays the theremin (TED, YouTube)

Although I would like get a full size theremin, they are priced way too high for what use I'd make of it.  So when a "toy" theremin showed up at http://www.thinkgeek.com I waited till they were back in stock and got one.

The theremin was originally the product of Russian government-sponsored research into proximity sensors by Lev Sergeevich Termen (Wiki).
1661058 Method of and Apparatus for the Generation of Sounds, L.S. Theremin (M.J. Goldberg and Son, G.M.B.H Germany), Feb 28, 1928, 84/674; 84/711; 331/37; 331/40; 331/55; 331/65; 331/181; 340/384.72; 984/383

1658953 Signaling Apparatus, L.S. Theremin, Feb 14, 1928,
340/562; 236/74.00R; 236/DIG.11; 246/2.00R; 246/63.00R; 246/249; 307/652; 331/176; 334/6; 336/30; 336/75; 340/590; 340/592; 361/1; 361/161; 361/181; 361/282; 455/120- any movement in a room will set off the alarm

2047912 Timing System, L Theremin, Jul 14, 1936,  307/2; 368/52; 968/827 - synchronous clock run on DC

Also see my Music web page.

Book: Theremin: ETHER MUSIC AND ESPIONAGE by Albert Glinsky, ISBN-13: 978-0252072758
Also see my music web page for other references.

Fig 1 Kit as received
Theremin

Fig 2 magazine all about Theremins (Japanese?)
Theremin



Electronic Goldfish in a Bowl

Runs on 3 AA batteries or an external wall wart.
Electronic Goldfish in a Bowl

Fireflies in a Jar

The jar has frosted glass and as the LEDs inside dim and brighten it appears that there's movement.

Butterfly on a string (Solar Wobble Butterfly)

From a distance it looks like a real butterfly when near a plant.  Can add a AA battery, but it's not required.  Not sure why you'd want to use one.
The plastic stakes are very fragile, i.e. they will break if you try to force them into the ground.  You need to have a hole first then insert the stake.

Butterfly on a string (Solar Wobble Butterfly)


Zendulum

A Zen Pendulum.  A magnetic ball generates an electric current when it passes over a coil that triggers the discharge of a capacitor giving it a small kick to keep it going.
Powered by a small solar cell or by a mini USB jack.  The black acrylic plastic has been laser cut, a neat idea.

The solar cell is an assembly made by Solarbotics who made this kit.  It has a printed circuit board on the back intended for one of their other kits.
The other kits use one of the MN1381 voltage triggers (MSE solar cell combo), like the MSE2 Powerful bundle kit.  The solar cell charges a big capacitor and when the cap voltage reaches the trigger point the 1381 grounds a terminal transferring the storage cap power to the load, which can be a small motor.

This may have an application for the Joule Thief idea.

There are a couple of errors in the instructions.
Step 8 - use the 1/2" screws, not the 1/4".
Step 10 - save the left over double sided tape, it will be used to stick the solar cell to it's mount.

By turning off the switch and letting the ball come to a stop as pictured in the photo below a "+" mark can be made on the top.
Now, after moving the "+" mark 90 so it's facing forward the switch can be turned on and the ball given a slight nudge.
After running for a number of cycles and switch is turned off.
The "+" mark is either at or near the top.

Note:  This electrical circuit has a lot in common with the Joule Thief.

Zendulum top
Zendulum bottom



An early version of this that used classical pendulum with a magnet on the tip is in Chapter 11 of the book: Junkbots, Bugbots & Bots on WHeels: Building Simple Robots with BEAM Technology by Hrynkiw and Tilden.  This book has a neat idea they call the Miller Solar Engine that uses a microcontroller voltage dropout detector IC to allow a solar cell to charge a capacitor that may have application to the Joule Thief idea of recovering energy.

If the ball is left on the rails and the Sun goes down the ball ends up in the center as pictured above.  The next day when there's light, but not direct Sun the ball and coil act like a loudspeaker and makes a faint beep that can take some time to track down.  This unit is NOT self starting, so even when in direct Sun the ball will not start moving, but just make the faint beep.

Links

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page created 7 April 2013.