simple theremin issues

Just looking through that schematic that tatems offered.

Wondering what C3 and C4 are?

they seem to be labeled 1 and 220 respectively with no units..

is pF implied?

Hum generally, when the unit is not specified, the capacitance is in µF, and it's logical there (voltage-invertion protector for 220µ and output-Hi-pass for the 1µ...

I built this tonight.

http://i4.photobucket.com/albums/y125/tatems/simple_digital.gif

thanks for posting.

to top it off i finished it while watching Theremin: An Electronic Odyssey with my girlfriend.


that was fun. I was done the soldering of the pots etc about the same time as movie finished.. and it worked first try! nice. I just did it on a bread board. not the nicest sounding thing.

i guess that's because it's a square wave?

what IC amp might you use if you were going to hook up a little 8 ohm speaker?

Congratulations!

Hum if you want to drive a speaker, look up to this schematic:
http://i7.photobucket.com/albums/y298/galaga_mike/fetzer-ruby.jpg

You can fix the gain at the value you like, this circuit can be very Hi-gain and cause distortion...

hm.. well that looks alot better than what i was trying..

i have an LM380n-8 which i was attempting to use.

instead of such a fancy amp circuit though I just connected the audio out directly to the Vin.

It definitely increased the volume but it affected they entire behaviour of the circuit compared to when i just had it going out to my computer speakers.

just built this
http://i4.photobucket.com/albums/y125/tatems/simple_digital.gif

worked first time but as was stated its not a very attractive sound. I do like the fact that you get a bigger sensitivity range though. Is there any way to make the tone out of this circuit more pleasing???

You might be able to fix that tone by using a lowpass filter to turn the square wave into a sine. However i'm not the person to talk about this stuff indepth. I'm just a humble music student!

This mod worked to tame the Theremax's square wave signal and it may work for you, too. I wrote this up to match the schematic for your theremin...

Solder a .001 mf ceramic capacitor to the junction of R5 and C3 and a 22K resistor to ground (you can use the ground side of R5), and connect the free capacitor and resistor leads together.

Thus, some of the high-frequency content of the square wave is diverted to ground. The resistor prevents an overly large signal loss.

You can experiment with different capacitor and resistor values to find the sound that you want.

Hope this helps.

You can also use a potentiometer rather than a fixed resistor, to have a variable filtration, with a control of frequency, and shape your wave as you like...

Hum, integration of a ramp-triangle wave gives a signal based on square polynomial functions, and can approach a sine wave.. I never tried but I think I will when i've all the stuff to make custom circuits...

I put in the capacitor n resistor that you suggested kkissinger n it's working pretty well, not a whole heap of difference but its a little less harsh. I'll try experimenting with different values later.