[volt-nuts] Voltage to frequency

DaveH info at blackmountainforge.com
Mon Jul 29 22:13:13 EDT 2013


The human ear is incredibly sensitive to frequency especially when two or
more notes are played simultaneously.

There is a large group of people who build analog music synthesizers and the
oscillator designs are fairly complex and very very accurate.

Music synthesizers use a scaling of one volt = one octave of pitch change so
there is accurate exponential conversion in the circuit too

These are meant to be played in hot nightclubs as well as air-conditioned
studios to temperature stability is good.

Here is one commercial example ($450)
http://www.synthtech.com/motm300.html

There are a lot of circuits in the public domain -- the old patents have
expired.

Here is Dr. Moog's last oscillator - the 921:

http://experimentalistsanonymous.com/diy/Schematics/Oscillators%20LFOs%20and
%20Signal%20Generators/Moog%20921.jpg

Some of the chips are no longer available so do not plan on copying this
circuit. There are two differential pairs with additional transistors -- one
is used for exponential conversion, the other for sine shaping.

Dave

 

> -----Original Message-----
> From: volt-nuts-bounces at febo.com 
> [mailto:volt-nuts-bounces at febo.com] On Behalf Of Charles P. Steinmetz
> Sent: Monday, July 29, 2013 14:09
> To: Discussion of precise voltage measurement
> Subject: Re: [volt-nuts] Voltage to frequency
> 
> Joe wrote:
> 
>  > Since it is relatively easy and inexpensive to have a very accurate
>  > frequency standard at home, I wondered how difficult would it be
>  > to use that standard to create an accurate voltage standard.
>  >
>  > *   *   *   Since this method apparently isn't being used,
>  > there must be some reason. Can anyone enlighten me?
> 
> As others have said, it is the [in]accuracy of V/F converters and the 
> complexity of having to make two accurate modules instead of just 
> one.  In somewhat more detail:
> 
> The V/F conversion can be done open-loop or closed-loop.  Let's say 
> that from the perspective of a time nut, interesting voltage 
> measurements/standards begin at 1ppm.  An open-loop solution can't 
> come close to that, particularly over temperature and time.  On the 
> other hand, a closed-loop solution requires building what you are 
> after in the first place -- a very accurate voltage reference and 
> comparator -- so why bother with the VFC?
> 
> When someone designs an open-loop VFC that is linear and accurate to 
> better than 1ppm over voltage, temperature, and time, we might have a 
> different conversation.
> 
> Best regards,
> 
> Charles
> 
> 
> 
> _______________________________________________
> volt-nuts mailing list -- volt-nuts at febo.com
> To unsubscribe, go to 
> https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts
> and follow the instructions there.



More information about the volt-nuts mailing list