[sdiy] current mirror for NPN expo?

[dan snazelle]

ok let me try that

i had the base going to the CV input instead of the ground




On Sep 19, 2011, at 12:39 PM, Lanterman, Aaron wrote:

> On Sep 19, 2011, at 12:15 PM, David G Dixon wrote:
> 
>>> can anyone point me towards info on how to use ONE NPN EXPO 
>>> to drive two vcos?
>> 
>> Can't you just mirror the current-sourcing one?  I.e., tie its emitter to
>> the other two, and connect its base to the other current-sourcing one?  You
>> should be able to replicate the current as many times as you want this way.
>> I did it with five transistors in a four-pole filter once; it worked a
>> treat.
> 
> I think this is an example, courtesy Jurgen and Rene:
> 
> http://www.uni-bonn.de/%7Euzs159/rs2040.png
> 
> Well, it's a VCF and not a VCO, but I think the expo converter illustrates David's idea.
> 
> - Aaron
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