How to check if my Op-Amp is damaged?

Violet's picture

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Joined: Aug 16, 2018

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How to check if my Op-Amp is damaged?
August 16, 2018 - 11:48am

Hi,

The circuit that I am working on has a hand full of comparators, amplifiers and buffers. For which we are using the LM741 and LM358 Op-Amp. 

Since we are just testing the design many times we doubt that the Op-Amp has been damaged (stopped working) whenever we don't get the desired results.

Is there a way to test if the Op-Amps are functioning properly?  I do not want to throw away the IC before making sure its damaged.

Also I do not have much test instruments with me, I only have a multimeter and a RPS.

Thanks

Violet

Ronald MC's picture

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Joined: Aug 17, 2018

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Checking Op-Amp using Multimeter
August 17, 2018 - 11:21am

Yes dear, you can use a multimeter to check if you op-amp is working properly. I have been using the LM741 and LM358 for donkeys ages now and I always use the below method to check if these guys are working as they are supposed to.

For this test it is recommended for you to have a dual power source, but it is not mandatory.

  1. Power the Op-Amp through Vcc and -Vcc pin. For simplicity lets assume Vcc=V and -Vcc=0V (ground)
  2. Connect both the input terminals (inverting and non-inverting terminals) to ground. Now if you measure the output voltage it should be 0V
  3. Now, connect the non-inverting terminal alone to Vcc(5V). The output should now be 5V
  4. Similarly check the same for inverting Pin. The output should be 0V when connected to Vcc

​Simply put we are checking the op-amp in voltage follower a.k.a voltage buffer configuration.

If all these conditions are satisfied then you Op-amp is working properly. 

Have fun. Enjoy electronics 

V GOPALA KRISHNA's picture

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Joined: Nov 05, 2019

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IC LM 358 checking
November 5, 2019 - 8:19am

Your explanation is good.  For people like me, if you can  explain the above with reference to pin nos. it will be more useful, becuase  we c'not understand what is 'inverting' / ,'not inverting' terminals etc. etc. I am a non technical person, but interested in experimenting in  electronics.  Thank you. VG KRISHNA from India. 

Violet's picture

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Pinout depends on IC name
November 5, 2019 - 10:41am

Hi Gopala Krishna, the pinout names depend on the part number of the IC. If you are talking about LM741 then Inverting input is 2, non-inverting input is 3 and output is 6. The LM358 has two op-amps inside. So it will be very different. You can refer to this website if you doubts with pinouts 

For LM741: https://components101.com/lm741-op-amp-ic

For LM358: https://components101.com/ic-lm358-pinout-details-datasheet 

Jayant's picture

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Test it in voltage follower mode
August 17, 2018 - 11:33am

Yes violet, many people get this doubt while testing their circuits. Here is what I learn from my senior to test an Op-amp, it is the quickest and simplest way and has worked for me every time.

Just connect you Op-Amp in voltage follower mode and make sure your input voltage is equal to the output voltage. That is power you op-amp with +5V and ground (or with any desired operating range) then short the output pin with the inverting pin and apply a voltage on the non-inverting pin. You should get the same voltage at the output pin. If yes then your Op-Amp is fine. If no time to change it.

But remember an IC would never get damaged by itself unless you have hurt it so bad, so make sure you find the fault in your design and correct it before substituting your IC with a new one

Read here if you want to know more about Voltage followers with Op-Amp

Violet's picture

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Op-Amp tested to be fine
August 18, 2018 - 4:51pm

As expected all the Op-Amps were working like a charm in voltage follower mode. I also tested them in comparator mode just to make sure they were good. So then I started tweaking my circuit and found there was a lame mistake in my connection.

Rectified it and now everything works fine. Thanks for saving my Op-Amps from being dumped