[sdiy] Odd OTA behavior

[Mike I]

Maybe the V(-) supply pin of the OTA is connected to ground instead of  V(-)
?



----- Original Message -----
From: Aaron Lanterman <lanterma at ece.gatech.edu>
To: SDIY <synth-diy at dropmix.xs4all.nl>
Sent: Thursday, April 24, 2008 1:03 PM
Subject: [sdiy] Odd OTA behavior


> I just got this e-mail from a student:
>
> >  I took the remaining 13700 and the 082 I was using and tried them
> > on another board and found that the 13700 wouldn't keep a steady
> > ~-13-14V at the Icon terminal - placing a resistor between +15 and
> > the terminal (trying with 520kOhm) would rise the voltage at Icon to
> > ~1.4V.
>
> I thought the voltage at a control pin of an OTA typically hung out a
> diode drop or two above the negative rail. What could he have done to
> make it measure at 1.4?
>
> (I'm thinking he probably hosed the chip somewhere along the line -
> blowing up a 13700 seems to be a rite of passage in my class; either
> that or he's flat out screwing up the measurement somehow.)
>
> - Aaron
>
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