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Old 12-05-2011, 05:37 PM   #5245 (permalink)
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Originally Posted by dave koller View Post
LM393. 0˚C to +70˚C. LM293. −25˚C to +85˚C

usually the specs are enough that 0 C should still work.. but a 293 would give it more leeway

I very much doubt that a cold weather malfunction is caused by the opamp. They are pretty stable, and an old design like the '393 far exceeds its original specs when moved to more modern processes.

The usual culprits are oscillators and capacitors. An crystal oscillator that fails to start up will just result in the controller not working, and being a little off-frequency won't even be noticed. Capacitors can cause more subtle problems. but there aren't any with critical values in the main circuit.

My speculation: the DC-DC converter didn't start up until it warmed slightly.
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