I have built a circuit (see attached image) based on the LT1115 op amp to amplify the output from accelerometers (model ACH-01). They are amplifying signals received that are in the low kHz range.
There are several problems, but the one I am most concerned with is that I have to unplug and replug in the accelerometers to get them to work after I've turned the power on. I've checked what I think is my drain current and it's normally between 10 to 20 uA (which is ok - if I understand the spec doc), but when I really move the accelerometers, the current can easily go up and over 100uA which (if I understand the spec doc) is beyond the saturation current and then they stop working until I replug them back in (a flat response or a little bit of higher frequency noise on the line). I'm sort of new to amplifiers... so if there's something I need to clarify I'm more than happy to do so.
Another major issue is that I've got 8 of these amplifiers for 8 total channels and certain ones don't work when others are connected.
They're powered in parallel from the filtered supply in the attached circuit. The best I could figure is that it was one of two things - either there wasn't enough power or there's some sort of grounding issue. I replaced the 9v batteries we were using with a PSU from a computer +/- 12v line to make sure it wasn't a lack of power issue. I know all the grounds are connected for the input signal and that ground is also connected to the output signal.
Also, from time to time there's a strange higher frequency noise in the range of 60kHz or 300kHz.
Any help is awesome as I've read from Horowitz and Hill and tried to find information on the internet, but it isn't quite soaking in.
There are several problems, but the one I am most concerned with is that I have to unplug and replug in the accelerometers to get them to work after I've turned the power on. I've checked what I think is my drain current and it's normally between 10 to 20 uA (which is ok - if I understand the spec doc), but when I really move the accelerometers, the current can easily go up and over 100uA which (if I understand the spec doc) is beyond the saturation current and then they stop working until I replug them back in (a flat response or a little bit of higher frequency noise on the line). I'm sort of new to amplifiers... so if there's something I need to clarify I'm more than happy to do so.
Another major issue is that I've got 8 of these amplifiers for 8 total channels and certain ones don't work when others are connected.
They're powered in parallel from the filtered supply in the attached circuit. The best I could figure is that it was one of two things - either there wasn't enough power or there's some sort of grounding issue. I replaced the 9v batteries we were using with a PSU from a computer +/- 12v line to make sure it wasn't a lack of power issue. I know all the grounds are connected for the input signal and that ground is also connected to the output signal.
Also, from time to time there's a strange higher frequency noise in the range of 60kHz or 300kHz.
Any help is awesome as I've read from Horowitz and Hill and tried to find information on the internet, but it isn't quite soaking in.
Attachments
-
41.7 KB Views: 39