[sdiy] TH XR2206 VCO tune pot

[Scott Gravenhorst]

Derek Holzer <derek at umatic.nl> wrote:
>Hi Scott,
>
>thanks for your reply. I did think of this, but since the range of 
>another pot in the schemo is restricted by following it with a larger 
>resistor, rather than putting resistors between V+/V- and the pot, I 
>thought that I would try to understand how that worked.
>
>best!
>Derek

I can understand how that could modify one end of the range, but not both.  I'll be interested to
hear how that works.

>Scott Gravenhorst wrote:
>
>> You can restrict the range of the pot this way:
>> 
>>      v+
>>      |
>>      |
>>      Ra
>>      |                                            
>>      |                                       
>>      P
>>      O<----- ...
>>      T
>>      |
>>      |
>>      Rb
>>      |
>>      |                                  
>>      V-     
>> 
>> Where POT is the original tuning pot and Ra and Rb are resistors you will add.  The
>> values of these resistors will have to be trimmed or calculated by you.  If Ra and Rb
>> are the same resistance as the pot, then the new range will begin at about a third of
>> where it was without Ra and Rb and it will end about 1/3 before it gets to the end.  I
>> can't guess what frequencies this will give...  Ra and Rb can also be trimmers so that
>> you can adjust the exact range you get.
>
>-- 
>::: derek holzer ::: http://blog.myspace.com/macumbista ::: 
>http://www.vimeo.com/macumbista :::
>---Oblique Strategy # 101:
>"It is simply a matter of work"
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-- ScottG
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-- Scott Gravenhorst
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