At 09:10 AM 5/7/01 -0500, you wrote:

>Just that we still don't know the input voltage, which is a major factor.
>He mentioned a dirty 18V, but I'd like to see at least a meter measurement,
>if not scope.

Ah, yes. If it was 18VAC, poorly regulated and full wave rectified, it might
be more like 30V, leading to almost 2W dissipation. At 65'C/W and 25'C Ta,
you'd need 1.9W to get to the 150'C Tj typical shutdown temperature.

>With the power levels mentioned though, I'm beginning to suspect oscillation.

I've never been able to get a 78M05 to oscillate, even without any load
capacitor. I suppose with really, really bad layout it might be possible, but
they are pretty sluggish devices.

Best regards,
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