In this Instructable, you will learn how to improve your collection of Snap Circuits blocks by adding a 555 Timer IC and building an optical theremin. You will learn the functions of the pins on the 555 chip. You will learn that when the 555 is in astable mode, the output of pin 3 is a continuous stream of pulses called a square wave that can be heard on a speaker as a tone. You will then learn how to build the optical theremin out of Snap Circuits. Finally you will learn how to play the instrument.

A theremin is a musical instrument that is played without actually touching the instrument. The original theremin used radio frequency interference caused by the movement of the player's hand to change the pitch of the instrument. The optical theremin depends on the intensity of light that falls on the photoresistor also controlled by the movement of the player's hand.

Currently there are no Snap Circuits sets that have the 555 Timer IC. So, you will need to purchase a 555 Timer IC from Allied Electronics or your favorite electronics supplier. If you don't have the Snap Circuits Extreme SC-750 set you can purchase the Snap Circuits Eight-Pin IC Socket block from C&S Sales. Adding these two components to your set of Snap Circuits blocks will allow you to create dozens of circuits built around the 555 Timer IC.

Snap Circuits is an educational toy that teaches electronics with solderless snap-together electronic components. Each component has the schematic symbol and a label printed on its plastic case that is color coded for easy identification. They snap together with ordinary clothing snaps. The components also snap onto a 10 X 7 plastic base grid analogous to a solderless breadboard. There are several Snap Circuits kits that range from a few simple circuits to the largest kit that includes 750 electronic projects.

All the kits include manuals printed in color with easy to follow diagrams to assemble the projects. The illustrations for each project look almost exactly like what the components will look like on the base grid when finished. Because the electronic symbol is printed on each electronic component, once the project is completed, it will look almost exactly like an electronic schematic.

Snap Circuits Parts:

1 Base Grid (11” x 7.7”) # 6SC BG
1 Eight-Pin IC Socket # 6SC ?U8
1 Press Switch # 6SC S2
1 100K ohm Resistor # 6SC R5
1 0.02uF Capacitor # 6SC C1
1 100uF Capacitor # 6SC C4
1 Variable Resistor #6SC RV
1 Whistle Chip # 6SC WC
1 Photosensitive Resistor # 6SC RP
2 Battery Holder (2-AA) # 6SC B1
3 Single Snap Conductor # 6SC 01
6 Conductor with 2-snaps # 6SC 02
3 Conductor with 3-snaps # 6SC 03
3 Conductor with 4-snaps # 6SC 04
1 Conductor with 5-snaps # 6SC 05
1 Conductor with 6-snaps # 6SC 06
1 Conductor with 7-snaps # 6SC 07

The above parts can be found in the Snap Circuits Extreme 750 set (I got my set from my local Radioshack store). Snap Circuits Parts can be ordered separately from http://cs-sales.net/sncirepa.html

Non Snap Circuits Part:

1 555 Timer IC # NTE955M This part can be ordered from radioshack.com

Optional Parts. I used these parts to connect my optical theremin to my mixing desk (reverb from guitar stomp box) to record the video:

1 1/8" to 1/4 adapter. This part can be found at Radio Shack (radioshack.com)
1 Snap Circuits Computer Interface Cable # 9 TLCI-73. This part is included in the Snap Circuits Extreme 750 set

The video of me playing the optical theremin follows below. Warning! Playing an optical theremin is harder than I thought it would be when I designed it. Be sure to watch the shadow of my hand as the shadow changes the pitch of the instrument.

Step 1: Insert the 555 timer chip into the Snap Circuits IC Socket block

The 555 Timer IC was introduced by a company called Signetics (later bought out by Philips) in 1972 and was designed by Hans R. Camenzind in 1971. The 555 chip has 25 transistors, 15 resistors and 2 diodes in an 8 pin DIP (Dual In-line Package) and looks like a square bug with eight legs. It has a notch at the top and Pin 1 is in the top left corner. (See picture 1) (Source: http://en.wikipedia.org/wiki/File:Signetics_NE555N.JPG)

The Snap Circuits Eight-Pin IC Socket block is picture 2 (source: http://cs-sales.net/eiicso6u8.html)

Insert the 555 timer chip into the Snap Circuits Eight-Pin IC Socket block. Make sure that the notch in the top of the 555 timer chip is aligned with the diagram of the chip pictured on the IC socket block. (See picture 3) (Source: http://www.snapcircuits.net/learning_center/designer)
Well done- with very lucid explanations! You could of course do this with&nbsp; a versatile &quot;snap circuit&quot; PICAXE microcontroller - see =&gt; <a href="http://www.instructables.com/id/quotSnap-connectorquot-PICAXE-microcontroller/" rel="nofollow">http://www.instructables.com/id/quotSnap-connectorquot-PICAXE-microcontroller/</a> . Some (high level) code would needed, but the component count would reduce.
dude u got some cheap ass theremin skillz
I did warn you beforehand: &quot;Warning! Playing an optical theremin is harder than I thought it would be when I designed it.&quot;
great explanation! those 555s are pretty cool

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Bio: You can try my projects AT YOUR OWN RISK. There's infinite ways to damage or destroy persons and property. I can't think of ... More »
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