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 Forum index » DIY Hardware and Software » Developers' Corner
CV- Keyboard
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synthesist



Joined: Feb 17, 2011
Posts: 79
Location: austria
Audio files: 2
PostPosted: Thu Feb 17, 2011 7:28 am    Post subject: CV- Keyboard
Subject description: how does it work?		 Reply with quote  Mark this post and the followings unread
Hey there!

I am new in this forum. Also I dont know much about electronics but I already buildet some cmos based drone machines.

So one thing I always wanted to know is wich kind of voltage do you guys get from a cv - keyboard? I have buildet a sequencer with the 4017 chip. Also I use LFOs for some control.
Is a CV input wich comes from the keyboard some kind of waveform or just the DC Voltage?

There is a simple method for making a VCO using the pll-4046 chip that i build. I can control it with my sequencer. So i thougt, I could just feed it by running some voltage from the battery throug a resistor into the same CV- Input. But it doesnt work. I tried different valued resistors. Maybe it should work with a voltage-divider?

Could someone explaine me this a little? Cause I didnt find some Information on this pages...
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DrJustice



Joined: Sep 13, 2004
Posts: 2112
Location: Morokulien
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PostPosted: Wed Feb 23, 2011 9:02 am    Post subject: Re: CV- Keyboard
Subject description: how does it work?		 Reply with quote  Mark this post and the followings unread
synthesist wrote:
Hey there!

I am new in this forum.

Hi!

welcome to electro-music.com!

Quote:
Is a CV input wich comes from the keyboard some kind of waveform or just the DC Voltage?

Just the DC voltage. For VCOs the standard control voltage is 1V per octave, or ca. 0.083V per semitone.

Quote:
So i thougt, I could just feed it by running some voltage from the battery throug a resistor into the same CV- Input. But it doesnt work. I tried different valued resistors.

This experiment, with the series resistor, may have worked, but possibly with a resulting VCO frequency out of hearing range. A series resistor acts as a current limiter, and since a CV input is high impedance and does not draw any current to speak of, the full voltage of the battery was seen by the CV input.

Quote:
Maybe it should work with a voltage-divider?

A voltage divider would work as a very basic CV source.

Quote:
Could someone explaine me this a little? Cause I didnt find some Information on this pages...

Rather than going into lengthy explanations here, I'll link to some excellent info at the Music From Outer Space site:

CV controllers in general
Monophonic CV/gate keyboard controller

DJ
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