Easy Theremin

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Introduction: Easy Theremin

This instructable is to build a one antena theremin (no optical unit) , battery powered; which coincidentaly has a fair resemblance to a green pig from the "Angry birds" videogame. A theremin is an electronic instrument that poduces sound waves without physicaly touching it. I wanted to build it for friend and it seemed an easy electronic project.
I got the schematics from this web page (in spanish, but the pictures are easy to read)

http://www.pisotones.com/Theremin/Theremini.htm

A small caveat, the resistor marked as 1.07 kOhms is a mistake. Its real value is 1.7 kOhms.

Step 1: B.O.M.

I used the following materials

1 x potentiometer 5K linear
1 x potentiometer 100K linear

------ceramic capacitors--------------

2 x 27 pf
3 x 15 pf
4 x 100 nf
2 x 4,7 nf
3 x 10 nf
2 x 68 pf


------1/4 W resistances------------

2 x 470 Ohm
2 x 100 kOhm
2 x 22 kOhm
2 x 4,1k or 3,9 k
1 x 3,3 megaOhm
2 x 1 megaOhm
1 x 47 kOhm
1 x 1,7 kOhm

-------transistors-----------------------

2 x BC546
1 x BC558 (or BC557)

------chokes------------

2 x 100 microhenrys

--------miscellaneous-------------------

1 - telescopic antenna
1 x 9-volt battery holder (recycled from a dead 9-volts battery)
1 x plastics casing (recycled from a Sogo orange juicer )
1 x On/off switch (I got mine from a scavenged computer)
1 x perfboard
1 x audio jack connector
1 x solder
1 x soldering iron
1 x shielded wire (less than 50 cms)

Step 2: Schematic Lay-out

I have taken the liberty to correct the value of the 1.07 k to 1.7 k in the drawing. The red squares are removed traces to avoid shortcircuiting. Just cut the copper using a blade or a multi tool. Confirm it with tea continuity function in a multimeter.

Step 3: Prepare the Case

I had a juicer laying around that we never use. So I emptied its interior and cut off a plastic stem it had on top. Avoid using metallic casings, they interfere in the signal.

Step 4: Solder Components Into Board

Step 5: Place Pots and Switch

I drilled the holes for the pots (hold by nuts), switch and jack audio (hold by glue).

Step 6: Final Touches

That´s it. Hot Glue the board to the case. Solder all connections and make sure that anything is loose. Connect your theremin to your computer speakers or stereo and off you go !.

2 People Made This Project!

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The schematic that "psst" provided it's completely wrong. If you pay attention, it has around 3/4 4k7 resistors that are not really in the diagram that is show in the instructable above.

Hope it helps

theremin fixed.jpg

Were did you get all the materials?

Do I HAVE to use ceramic nonpolarized capacitors or will electrolytic polarized capacitors work?

Hello everyone! I have tried to make this but it's not working for me. Can someone please tell me if there is a mistake in my circuit? And if anyone has some tips to help me get a proper sound out of it, that would be helpful too!

theremin.jpgtheremincircuit.jpeg

Hi in your video (the one with the frog), you had another schematic could you post that? it included a LM386 amp. many thanks

Don't you need a coil for this

Which potentiometer goes to which knob. It's not specified.

i've built it and it works, but i think it have some issues:
-low signal (compared to a guitar), it's that normal?
-a horrible groundy noise: it increase when i touch the chassis jack, and decrease when i touch the metal cover the plug of the cable...
-it doesn't sound when i'm not touching the "tune" pot.

it seems like a ground trouble... what do you think? i normally built electronic projects in metal cases, so i don't know how to ground this thing...

Thank you a lot, and sorry for my argentinian english

Used wrong account, sorry! Please respond to this account so I'll get notified. ( I no longer have the email account to thenuclearlemons)

Where did you find a 3.3 megaOhm resistor?