Absolute value voltmeter error

[lats]

Dear all
m designing a voltmeter circuit which gives the absolute value of the input voltage (i.e , if the polarity at the input voltage side changes the output will be the same voltage with positive value).

the problem is the circuit works well with all the voltages (range -2V to +2 v) but when i give 0 volt at the input the output should give me 0 volt but m getting 146 mV output. the opamp i want to use is LM324 only .

Please help me out. how to correct this ?

 

[engr.waqas]

This is offset voltage of your opamp.
Use offset null pin to make it zero if your opamp has this pin or use a opamp with this feature

 

[lats]

I can use only LM324.

 

[engr.waqas]

why u can only use LM 324??

 

[lats]

Because of cost factor and is compulsory requirement in this project

 

[engr.waqas]

I dont think 146mv is a issue in a low cost design
There are many factors which contribute in such situations like offset voltage of a amplifier(it is output voltage that is present even at no input),noise effects and many more.

 

[lats]

so what is the solution m asking.....???????

Added after 3 minutes:

thanks anyway i got the solution