OBERHEIM SYNTH

Anyone here designed circuits using a transconductance amplifier - specifically the 3080E used all over the OB-X? 

I designed a simple 3080 circuit (based on the chip A6 3080 circuit on the OB-X mother board) that was intended to let me control the noise level on my OB-X using the PWM amount knob.  But in just trying to calibrate it I burned up 5 3080 chips and a few transistors.  I just don't get it -  based on my calcs everything is well within ratings.

I thought there might be someone here that has played with these things that could help me see what I am missing...

Thanks - and happy new year.

As I recall from high school the CA 3060 has a very low control  
current tolerance, in the order of microamps. Did you current limit  
the control voltage adequately (at least 2 Meg resistor as I remember).

Stublito

  aQuoting nelsonj_sce <nelsonj_sce@...>:

> Anyone here designed circuits using a transconductance amplifier -   
> specifically the 3080E used all over the OB-X?
>
> I designed a simple 3080 circuit (based on the chip A6 3080 circuit   
> on the OB-X mother board) that was intended to let me control the   
> noise level on my OB-X using the PWM amount knob.  But in just   
> trying to calibrate it I burned up 5 3080 chips and a few   
> transistors.  I just don't get it -  based on my calcs everything is  
>  well within ratings.
>
> I thought there might be someone here that has played with these   
> things that could help me see what I am missing...
>
> Thanks - and happy new year.
>
>
>
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