sushidhar
Newbie level 1
OP-AMP help
I hv designed a differential amplifier circuit using two OP07. This was designed to amplify a minimum of 0.01 mV.
The desired gain was 21*30(21 on one,30 on the other)
For the first Op-amp i chose MFR resistances of R1= 68 K-ohm, R2= (1000+470) K-ohm in series
For the second Op-amp i chose MFR resistances of R1= 33 K-ohm, R2= 1000 K-ohm
On circuit completion i found the gain to be 30*30 (the gain of first increased from 21 to 30 though gainof second remained same)
Secondly, when the circuit was used for amplification of the signal, i found that the output of the amplifier took a really long time to come back to its initial level (0 volts) after i had turned off the input.
For example an input of 0.01 mV gave us an output of around 9 mV but it took 10
minutes to come back to its initial level (0.00 V) after switching off the input.
PS: circuit img. is shown below 4 a single op-amp. We have just used two op-amps in series
.
I hv designed a differential amplifier circuit using two OP07. This was designed to amplify a minimum of 0.01 mV.
The desired gain was 21*30(21 on one,30 on the other)
For the first Op-amp i chose MFR resistances of R1= 68 K-ohm, R2= (1000+470) K-ohm in series
For the second Op-amp i chose MFR resistances of R1= 33 K-ohm, R2= 1000 K-ohm
On circuit completion i found the gain to be 30*30 (the gain of first increased from 21 to 30 though gainof second remained same)
Secondly, when the circuit was used for amplification of the signal, i found that the output of the amplifier took a really long time to come back to its initial level (0 volts) after i had turned off the input.
For example an input of 0.01 mV gave us an output of around 9 mV but it took 10
minutes to come back to its initial level (0.00 V) after switching off the input.
PS: circuit img. is shown below 4 a single op-amp. We have just used two op-amps in series
.
