I have got a AD620A to amplify the output. But the inamp output wave form i get is a half wave sine. When i used a 741s to make a homebrew inamp, i also got a half sine wave i dun think its the load cells signal, but also i cant check, the schools equipment cant check the small signal. The output from the load cell seems to be riding on the half wave sine.
I think the noise is very high and the ammeter reading i get when not connected to anything are even higher that our load cell output. I was told by thet lab tech that the power supply's ground is not a true ground. So i did not ground the load cell. However, when i did, the output from the inamp changed, the half sine waves decreased in amplitude, and also the output will also turn into an almost straight line when i step on the load cell.
I also tried connecting a capacitor parallel to the load. But, the whole output turns to a negative and wont even react to the load cell output.
So how can i reduce the noise(im not sure if it is noise, but the amplified outputs have half waves, i am thinking of low pass filters but im not sure)? Also any comment on setting the gain for the device? Thanks.