| ??? 01/18/10 18:16 Read: times |
#172552 - when within specified range!!! Responding to: ???'s previous message |
differential-ADC has around 120-130dB. CMRR
when within specified range!!! which 20V is not. usually the CMRR spec only hold till Vin + Vcm is less than Vce Oliver, you mean to lift the ADC GND proportionally along with a resistor in its GND path . if that is what Oliver means take him out to the woodshed. What you need, for any reasonable precision is an chopper stabilized op amp with same base ("gnd" [20V]) as the loadcell and then some means of level conversion or isolation to the rest of the circuitry -OR- as below one question: whhy cant you make all the circuitry have "gnd" at the 20V? Erik |
| Topic | Author | Date |
| Isolating xducer | 01/01/70 00:00 | |
| not even a way | 01/01/70 00:00 | |
| noise | 01/01/70 00:00 | |
| I wouldn't do that... | 01/01/70 00:00 | |
| agree | 01/01/70 00:00 | |
| when within specified range!!! | 01/01/70 00:00 | |
| why 8V or 20V | 01/01/70 00:00 | |
| no specs violated | 01/01/70 00:00 | |
| that is TOTALLY irrelevant | 01/01/70 00:00 | |
| Jumping to conclusions | 01/01/70 00:00 | |
| AC modulating the bridge excitation voltage? | 01/01/70 00:00 | |
modulating the excitation | 01/01/70 00:00 | |
| make it simple at start | 01/01/70 00:00 | |
| making it | 01/01/70 00:00 | |
| o, i see... | 01/01/70 00:00 | |
| from my experience with loadcells ... | 01/01/70 00:00 | |
| what is exactly "xducer" ? | 01/01/70 00:00 | |
| Offsetting a signal | 01/01/70 00:00 | |
| Yes but...? | 01/01/70 00:00 | |
| Error analysis and budget | 01/01/70 00:00 | |
| Common Mode suppression | 01/01/70 00:00 |