On Wed, Sep 18, 2019 at 9:38 AM Curtis Dutton <curtd...@gmail.com> wrote:
> On Tue, Sep 17, 2019 at 6:17 PM Chris Albertson <albertson.ch...@gmail.com > > > wrote: > > > If you want better than 16-bits and 1KHz then you also are going to need > a > > very good quality analog signal conditioning and instrumentation > amplifier. > > The analog circuit between the A/D converts and the load cell really > does > > matter. You have to reject common-mode or the low bits will just be > > filled with 60Hz noise. And you can not simply use a "brick wall" filter > > or you will not get the desired bandwidth through. (If you are needing > to > > sample at 1K then you must care about 500Hz bandwidth. > > > > This matters a LOT more than which A/D chip you use What you need is a Analog Front End (AFE) that is designed specifically for a strain gauge. Usually that's a single IC (that probably requires some passive components around it, which are specified in the datasheet) and if you're not designing your own circuit board there are little circuit boards ready made that you can get from Amazon that take the wires for a strain gauge on one end and wires for power and SPI on the other end. There's a IC called HX711 that's popular with Arduino enthusiasts. If you are building your own circuit board, the various AFE manufacturers (Texas Instruments, Analog Devices, etc) tell you exactly how in their datasheets, application notes, and reference designs. The difference between a AFE and A/D converter is that a AFE has the A/D and also all the amplification and filtering etc built in to the chip, whereas you'd have to build a pretty complex circuit board to do all of that with discretes and op amps, and your results won't be as good as the AFE chip. _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
