Linear current source

[Aural Research Facilities]

>  The A of E has a "Good Circuit Idea" that is called "Howland Current
>  Source for driving current controled voltage-current devices(or something
>  like that)" - that's OTAs - right? So I built this, seeing a linear
>  relationship bewteen Vin and control current - but it didn't seem to do
>  anything when I hooked it up to an OTA. Do I need a resistor bewteen the
>  PNP and the OTA pin (I thought this might be the problem this morning -
>  so I didn't have time to try it)? Will this work for 3080/13600 type
>  OTA's where the control pin is at -V+.6?

The CA3080 that is powered from a bipolar power supply such as a +/- 15VDC
supply will have Pin 5 (Current Input pin) at -15 -0.6 volts.  Or -14.4VDC.
The linear reference is therefore in relation to -14.4V instead of ground.

Here's to hoping that that bit helps, anyways.  :)

Ric


                       Aural Research Facilities
        "Building the lowest cost modular synths, in the .... :) "
                           rmiller at pangea.ca
                     http://www.pangea.ca/rmiller