nice quiz. Can't wait for the solution!
On Friday 28 May 2010 17:37:47 email@example.com wrote:
I would say it is an effect of the power-supply. As others stated, 50Hz=20
switching power supplies produce distortions of 100Hz (and of much higher=20
Here I think these affect the op-amp of the input by modulating the supply=
voltage and/or the reference-voltage. This could probably be fixed by more =
better capacitors stabilizing the +5V (or +12V).
My guess why the development engineers didn't catch it:
a) They used a high-quality lab-power supply during development which is=20
stabilized far better then the consumer psu that is shipped.
b) Someone swapped the high-quality capacitors for lower-spec ones at the e=
of the development cycle to cut costs.
c) The capacitors in your special device just broke their smoke-seal. Bette=
refill them soon:-)
BTW: The graphs would be better to interpret if both had the same x-axis-
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