Instructables

We all know that a 555 noisemaker is easy to build. But her's something more original, a 555 paper theremin.
It's just a piece of paper with a 555 noisemaker driven by a phototransistor, so it sounds when you place something above it, changing the tone depending of how close the object is.
 
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Step 1: Materials

Picture of Materials
Material i need to buld it:
-A piece of paper
-Copper tape
-Tab wire
-A flux pen

-A 555 IC timer
-A 330ohm resistor
-A bc548 transistor (any NPN transistor will work)
-A phototransistor
-An IR LED
-2x 680nF capacitors
-A 5k pot
-An 1k resistor

Step 3: The tape circuit

Making the rest of the circuit was pretty easier. I gave it a nice appearance placing the traces squarely.
The flat IR LED you can see in the first pics was not bright enough, so i changed it for a 5mm one.

Step 4: Soldering the traces

I tried several ways to solder the traces, but when i used resin, it left a stain, and without it, the soldering was rough and ugly.
I had some tab wire left from a solar panel and a flux pen. I tried them and i realized that is was the best choice.

I applied flux to all the joints and soldered a small piece of tab wire i each one. The result is marvelous but is enough for me.

Step 6: Finished and working!


Finally, i cutted the paper in size and i added a copper edges.
After some testing i realized that human skin is not reflective enough to make it work, so a higher gain transistor can be added, or, as i did, to wear gloves with aluminium foil underneath, that reflect the IR light.

If you liked my instuctable, please, vote me in the Epilog laser, pocket-sized electronics and DIY soundhack contests.

Feel free to ask me anything you didn't understand or propose upgrades.
please anyone tell me, what is the size of the copper tape in mmxmm!
The tape is 5mm wide and about 0.02mm thick.
thank you :-)
how did u stick the copper tape on the paper?
ElZorro1 year ago
Nice
Really cool actually
but not a theramin
Dr. dB ElZorro1 year ago
Quite true. A second sensor/555 circuit to modulate the first one would make more of a Theremin out of it.

But what an interesting and unique form-factor, if somewhat delicate! (I'd imagine you have to be pretty quick with the iron, to avoid roasting clean through the paper, too.)
rpb1 year ago
Nice.

Would it be hard to add a second photodiode (or LDR, perhaps?) and a cheap op-amp, maybe, to give volume control with your other hand?

Then all you'd need to do is get it to produce a slightly more pleasant tone (!) and you'd have quite a passable instrument for playing to an audience! I wonder if you could make a low-pass filter with another LDR right next to the volume one (or something like that), with a different capacitor, to create a variable low-pass filter that cuts off some of the higher harmonics (which would make the sound less "buzzy", but could perhaps track the tone, rather than just having a fixed low-pass filter that would filter different tones irregularly).
Dr. dB rpb1 year ago
The 555's unaltered output sounds kinda "unpleasant" 'cause it's a square wave, which does, indeed, shed lots of unplanned upper harmonics. It can be "integrated", however, through a short series of R/C filters, into triangular, then sine wave forms. I don't have such a "function generator" circuit handy at the moment, but that's something Google's pretty good at. (Or maybe somebody's already made that 'ible?)
Very cool concept and execution!

You might save a bit of time by bending the tape around corners, rather than soldering right-angle tapes together. Fold it over itself at an angle (now the adhesive is upward) and then fold it over again. The sum of the angles of the folds is the new direction of the tape.

I'm also curious whether the adhesive is non-conductive enough that you can run one tape directly over another without cutting out paper squares.


Yes! That's exactly how we used to "fold a corner" into the old-school, metallic "window-tape" in the alarm business. Of course, that was self-adhesive so you could just burnish it down with the little trick applicator roller and you were done. (Much of that product-type was also silver-colored, so probably either tinned copper, which would solder-up just fine in this kind of application, or straight aluminum foil, which would decidedly NOT.)
pinomelean (author)  ChrisPhoenix1 year ago
Yes, the glue is non-conductive.
t8001 year ago
cool project ;-) ...reminded immediately of Sheldon Cooper! :D Well done :-)
New to all this. What are the square things with the 2 wires coming out? It's the only thing you didn't label in the pictures.
pinomelean (author)  thats_how_i_feel1 year ago
They're two 680nF capacitors.
Thank you.
nodcah1 year ago
Great ible! This is definitely an upgrade in difficulty fron mine. Keep up the great work!
pinomelean (author)  nodcah1 year ago
Thanks.