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Transistor vocoder? Answered

Hello, last night i was experimenting with my breadboard, and i came up with an idea, transistors have a supply voltage, which the small voltage controls pitch and volume. but i thought what if i had voice coming in to the supply voltage part(after being super amplified) and the keyboard comes in the control voltage side, would the keyboard not control pitch of voice, while voice modulates? thanks for your help.


What you're talking about is a voltage controlled amplifier. When fed with an audio-frequency control signal as well as audio-frequency input, that will essentially function as a multiplier and thus produce ring modulation (https://secure.wikimedia.org/wikipedia/en/wiki/Ring_modulation). Not a vocoder, but it is a classic sound effect. Ring modulation with a single reference note was used to produce a lot of SF critter voices; the Daleks from Dr. Who may be the one you're most familiar with.

If you want a low-budget vocoder-like effect, I'd suggest looking at the "talking guitar" effects. These used a speaker firing through a tube into the person's mouth. That doesn't get directly combined with their voide, but it uses the resonances of the vocal cavity to shape the instrument's sound. Of course you then pick up the results with a microphone for recording or amplification, generally the same mike you were using to pick up the singer's voice.

I have a talkbox currently, I use it for my synth, but this effect you speak of is able to control pitch of voice a little, am i correct? thank you.

Yes, ring modulation will respond to pitch.

Basically, ring mod can be thought of as generating side tones -- the sum and difference of (each of) the frequencies on the carrier vs. those of the modulation.

The result may not be particularly musical, though mixing the source material back into it might help.

Since it's cheap and easy, you could try it and see if you like it. Though personally I always lean toward an op-amp based circuit for audio processing rather than a single transistor, since that avoids having to deal with all the details like biasing the signal so it's in the linear region of the transistor's response curve to avoid distortions you didn't intend to produce.

You say there is a way to make it from op-amp IC's, such as 386's? If there is such a way, could you give me a schematic, or even a hint? haha i would love to build a homemade vocoder with much simplicity...

Not vocoder. Ring modulator.

Vocoder simply can't be done that simply. Period.

So what would you say is the most simple form of a vocoder? Is is possible? haha

https://www.instructables.com/id/Build-an-analog-vocoder/ is a relatively simple design. How complicated and expensive it gets depends on the number of filter bands (and width of those bands) used.

So, if i wanted to get something like a vocoder, that is cheap, what would you suggest for the most simple form of a vocoder?

("voide" was supposed to be "voice", of course. Tupohgrapcal eror.)

A single transistor will not control pitch.