>I am using ST 7812 regulator the problem I face is the voltage out
>I get normally is constant 11.9 or 12.03 V.  Some of the parts after
>use for fews day or 1 month, the voltage out drop to 8.9 V and it
>is unstable waving between 8.9 to 11.9 V. What is the reason of this
>and how to avoid this ?

RTFM and see where to fit capacitors to stop supersonic oscillations. It
will not matter if the data sheet is for another manufacturer, they all
specify the same capacitors in the same positions.

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