Input goes from 30 to zero every couple of s for arduino, stable on multimeter

hi,
i'm using arduino uno read output of current sensor, goes through lm358 (non inverting amplifier configuration) , directly a0. on a1 i've reference voltage (a threshold compare current signal to), using trimmer.

my problem that:

• on a1 (trimmer) analogread ok (reads 10, ~50mv on multimeter)
• lm358 output ~50mv too, according multimeter, , stable
• lm358 output directly connected a0. arduino readings follow (with delay(100) in loop)

code: [select]


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do have idea?

quote

do have idea?

several!
post code, using code tags.
post wiring diagram (hand drawn, not fritizing).
for instructions, read "how use forum" post , follow directions.

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