| ??? 04/22/11 11:22 Read: times |
#181972 - further noise analysis Responding to: ???'s previous message |
Justin Fontes said:
a reference ground from the motor supply (as in my case), I would also recommend using a very short thin trace that connects the ground from one to the other. The other issue is proximity. If you are sure proximity is not causing the deficit then I would try the above. I have even tried replacing the ball bearings in the motor with ceramic ball bearings and making sure that no part of the motor makes electrical contact with any other portion of the chasis. Basically, isolating the motor from the acquisition sensor, altogether. I have found that just isolating the body of the motor works quite well and that over time (as the bearings set in, the grease dries up) that noise increases on my signal. The most bang for the buck is definitely two isolated supplies. Also, isolate the sensor from the chasis. I think that isolating the sensor may prove easier. These methods work for about 30db of isolation, after that averaging needs to be employed. Its known to me that using isolated DC/DC or different batteries would solve the problem but that would add additional DC/DC converter or battery . I am searching some standard/custom type of line filter to do the trick . Erik Malund said:
if one grpond 'floats' i.e. only is grounded through the connection to the other device try using a twisted pair for Vcc (or Vwhatever) and ground.
Erik Video section shares this GND. The below picture shows the waveform when it operates. http://www.8052.com/users/apc/screensss.JPG -Ap |
| Topic | Author | Date |
| Noise originating from servomotor | 01/01/70 00:00 | |
| Filters | 01/01/70 00:00 | |
| filters | 01/01/70 00:00 | |
| 3 wires servo | 01/01/70 00:00 | |
| Use two different supplies | 01/01/70 00:00 | |
| may sound silly, but | 01/01/70 00:00 | |
| further noise analysis | 01/01/70 00:00 | |
| Filtering is no option here... | 01/01/70 00:00 | |
| questions | 01/01/70 00:00 | |
| Answers | 01/01/70 00:00 | |
| my experience is ... | 01/01/70 00:00 | |
| Couldnt find much difference | 01/01/70 00:00 | |
| Ground impedance? | 01/01/70 00:00 | |
| One last bit of information that may help... | 01/01/70 00:00 | |
what we do | 01/01/70 00:00 |