Voltage amplifier (mV)

[rodrigobg]

Hi, I'm using a MPX2010DP pressure sensor to build a differential manometer, the output voltage of the sensor is between 0 - 20 mV and I need to send this voltage to a ADC converter but this voltage is very low so I need to amplify it with a gain close to 100, I tried with a non inverting amplifier with LM324 but it did'nt work, any suggestions??

 

[ericgibbs]

Hi, I'm using a MPX2010DP pressure sensor to build a differential manometer, the output voltage of the sensor is between 0 - 20 mV and I need to send this voltage to a ADC converter but this voltage is very low so I need to amplify it with a gain close to 100, I tried with a non inverting amplifier with LM324 but it did'nt work, any suggestions??

hi,
If you post your LM324 circuit we may be able to help.

 

[simonbramble]

You will probably find that the input offset voltage of the LM324 is large compared with the signal you are trying to amplify. You need a component with a lower offset voltage.

 

[alec_t]

Max input offset for the LM324 is specified as 5mV, subject to a drift of max 30uV per deg C. You could null this offset with a suitable resistor/trimmer connected to V+ or ground as appropriate, or you could use a precision op-amp instead of the LM324.

 

[simonbramble]

OK, post your circuit and let's have a look. Looking at the input impedance of the LM324 it should not load the output of your sensor (this is 3k). The LM324 senses down to 0V when running off a 5V supply, so the op amp is capable of seeing the 20mV output from the sensor. It therefore sounds like it could be a circuit issue (or you have wired it up wrong). Post your circuit and we can look at it

Simon