On 2013-08-17 7:56 PM, RussellMc wrote:
> VG
>
> This is the original thread and these were my comments at the time:
> [...]

I checked the power supply lines with the oscilloscope and there doesn't
seem to be any stability issues or oscillation at all. I'm also using
+/-14V transient voltage suppressor diodes on the power lines.

I would draw up schematics, but this is happening with quite a few
different types of ICs. I've noticed that the TO-220 (without heatsink)
type packages are not failing, so it might be a heat dissipation issue
with the plastic DIP packages. Still strange since I'm pretty sure I'm
operating well within the specifications of the plastic DIP parts.

I've also noticed that lowering the opamp and MOSFET gate driver supply
voltage to 0/5V (red PSU wire) from -12/+12 volts (blue/yellow wires)
/greatly/ reduces operating temperature and failure. I don't get it -
the opamps are fully specified to +/-20V or more and indefinite output
short circuit. Might be something funny happening with the +/-12V power
supply lines, but same result was observed from two different power
supplies tested.
--=20
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