I use Lm35 to measure PV panel surface temperature with a cable its long is almost 1 meter but i displayed the output on oscilloscope and there is spikes added to the dc output how to cancel these spikes( i don't have any specified frequency )

 

Hello,

Did you see the schematics in the datasheet for remote sensing?
The figures 5 and 6 in the datasheet might give you a hint.

Bertus

 

Can you show us the circuit to see how you interfaced LM35.
LM35 may be interfered by the circuit to which it is connected.
Show me that circuit? Is that an ADC?

 

Can you show us the circuit to see how you interfaced LM35.
LM35 may be interfered by the circuit to which it is connected.
Show me that circuit? Is that an ADC?

there is no circuit it is just the output of LM35 connected to oscilloscope .

 

A resistor in series with the output and a capacitor to ground at the end of the wire to form a low-pass filter should help. Try 1kΩ and 1μF to start.

 

Then try connecting module LM35 as shown below.

 

A resistor in series with the output and a capacitor to ground at the end of the wire to form a low-pass filter should help. Try 1k? and 1?F to start.

Since the solar panel temperature is unlikely to change faster than a couple of 'C per second, that's a max voltage slope of 20mV/sec on the LM335 output pin. You could probably use a 100uF or 1000uF cap with no issues.