[sdiy] Linear detuning !

[Michael Zacherl]

Hej,

just a pointer: http://home.swbell.net/roy_tate/info/lindetun.html

:-)  Michael.

karl dalen wrote:

> Hi simon
> --- simon.oo.o at xs4all.nl skrev:
> 
> 
>>Hi Karl,
>>
>>karl dalen zei:
>>
>>>Here we go.
>>>
>>>Now, if  we add a tiny DC voltage to Iref
>>>summing point we offset the VCO what if we
>>>use the Expo CV voltage as the offset voltage?
>>>
>>>Constant multiplication of a varying linear voltage! Ugh!
>>
>>Linear detuning means that the frequency is increased by a constant
>>amount, for example, instead of 100 Hz or 5000 Hz you want 100.1 or 5000.1
>>Hz.
> 
> 
> Yes i know, i was just one of my "fun" ideas!  
> 
> Lets expand the wicked idea, we have two inputs to 
> the NPN expo, B1 and B2, apply positive voltage V1
> to B2 and frequency increases apply V1 voltage
> to B1 and frequncy decreases. If we match the input 
> resistors R1,R2 but let one of the divider resistors
> become a pot, we can under compensate the expo.
> 
> As the V1 increases on B2 the voltage on B1 also increases
> wich counteract the V1 voltage on B2 but if we make this "same"
> voltage a fraction of V1 on B1 , a varying constant of the beat
> over octaves then beat would stay constant!
> (or close to).
> 
> However impedance on B1 might be wicked but not as a
> sensitive matter as on B2.
> 
> The idea are, create a "scale voltage that equals the beat you want!
> Ie, 1.000V scale on B2, and 0,002V scale on B1 automatically 
> logs to constant beat over octaves if trimmed carefully!
> 
> Perhaps to difficult to tune!
> 
> Reg
> KD
>