Below is the circuit with BJT buffer transistors.

quick converted the Crutschow's schematic and tested in spice for least error & frequency ↓↓
(( while i'm still no fully aware how the particular opAmp biasing works -- truly amazing circuit ! ))

multidude → . . . (LM6142) →

 

quick converted the Crutschow's schematic

Why do you take a simple circuit and make it complex?

 

Because of many : ( at 1-st i just checked the circuit out from personal interest →it was less time consuming to replace the feedback net of the existing tested circuit - rather than completely remake it← - then i thought to upload the R0 to R2 relation *formulas ... then the whole test for it* to be more clear . . .) , to preserve the comparison base with what i struggled , to avoid near 0 jumps , to expand it to be tested with the multitude of OpAmps , ? ....

??? there is something absurdly wrong ↑↑ with it (#41 last fig.) ↑↑ it should be 10x to 20x faster ???

. . . here ? . . . so same for last fig. ((ok ))
+10kHz (but less "linear" frequency range)

 

Hey people, do you think its possible to use the LT3092 for this ( is this bipolar) I saw there is one application with DAC Controlled Current Source. Do you think that could be of use....?

 

do you think its possible to use the LT3092 for this

No, not even close.
That is a unipolar, resistor/potentiometer controlled current source.
You need a bipolar, voltage-controlled current source.

 

there is something absurdly wrong ↑↑ with it (#41 last fig.) ↑↑ it should be 10x to 20x faster ?

Sorry, but your kludgy circuits are too difficult to follow.
You'll have to analyze the problem yourself.

 

No, not even close.
That is a unipolar, resistor/potentiometer controlled current source.
You need a bipolar, voltage-controlled current source.

Thanks a lot, I had the same feeling... just wanted to make sure.

 

Hi Gents, just had the time to get that problem solved, I in the end used the LT 1990, just in case somebody needs that application. ( goes up to 100mA....

 

and works perfect.... up to 250 OHMs