LM158-N: LM158-N-The high temperature test is abnormal

Hi,

what are the supply voltages? What are the resistor values?

If the circuit is instable, a small cap in the 10...100pF range in parallel with the feedback capacitor can help. Also, do not connect the voltmeter directly to the output of OPAmp but insert an isolation resistor of 100...220R first. Any capacitive load can otherwise destabilize the OPAmp.

With a too high resistor at the +input of OPAmp the circuit can become instable and due to unwanted capacitive feedback from the output of OPAmp to the input. So, it's a good idea to mount a small cap in the 10...100pF range from the +input of OPAmp to signal ground.

Also, have you added decoupling caps close to the OPAmp?

Can you show a photo of the printed circuit board?

Kai

The power supply voltage is changed from 24V to 12v, and then the partial voltage is 10V. After the front section is linear (including the detection filter), it is amplified to 2V ~ 18v, and the current power consumption does not exceed 10mA

Hello,

The LM158-N can only output to 4V below the positive supply rail, you may be hitting an output voltage swing limitation. Where are the two multimeters connected measuring the voltage?

Additionally, why is C5 100uF? That is a very large capacitor.

Best,
Jerry

The meter is right to the ground, so instead of using 100uf for C5, how much capacitor should I use,

The meter is right to the ground, so instead of using 100uf for C5, how much capacitor should I use,

The capacitance at position C5 is 100PF,0.1ufde

Hello,

Do you need a certain low pass filter value on the output of your op amp? This is what the output capacitor is doing. Typical load capacitance for the LM158-N should be in the tens of pico-farads range.

Best,
Jerry