| ??? 10/14/08 21:37 Read: times |
#159063 - Hand-tuning is not cheap! Responding to: ???'s previous message |
Steve M. Taylor said:
Richard Erlacher said:
Are you saying that this DDS is completely adjustable under control of the MCU, or does it require manual calibration to match the LVDT? Yes. The Wien-bridge oscillator offers no such benefit. No. What's involved in automatic calibration to a specific LVDT, if it's practicable? At the "zero position" adjusting the frequency until any residual output is also zero phase. Is there a way to do this automatically, i.e. without any hand-tweaking of each individual unit? Steve
What would be of maximal benefit would be to have the system self-calibrate. Once a human has to touch the unit, i.e. at the bench, with a screwdriver or whatever, it matters not what he's adjusting. If, for example, it were possible to put the LVDT into a known position, so that the phase output were known, then calibration could be automated, couldn't it? If it has to be handled by a technician, it could just as well be done with an op-amp Wien-bridge oscillator costing less than a dollar. The calibration cost will far exceed the cost savings under such circumstances. Setup and measurement for calibration can easily take half an hour, and there's much room for error. If it has to be, then it has to be, but it would be really desirable to cook up a procedure that didn't require hand-tweaking of each unit. RE |
| Topic | Author | Date |
| Function Generator IC | 01/01/70 00:00 | |
| Better? | 01/01/70 00:00 | |
| Maxim | 01/01/70 00:00 | |
| Maxim unavailable | 01/01/70 00:00 | |
| DDS? | 01/01/70 00:00 | |
| Better? .5% -1% THD with discrete solution? | 01/01/70 00:00 | |
| Wein bridge? | 01/01/70 00:00 | |
| Simple wont do ... | 01/01/70 00:00 | |
| LVDT driving | 01/01/70 00:00 | |
| High performance can be simple | 01/01/70 00:00 | |
| Tuning | 01/01/70 00:00 | |
| DDS again | 01/01/70 00:00 | |
| Design. | 01/01/70 00:00 | |
| What frequency? | 01/01/70 00:00 | |
| frequency | 01/01/70 00:00 | |
| Err | 01/01/70 00:00 | |
| DDS again | 01/01/70 00:00 | |
| THD | 01/01/70 00:00 | |
| THD | 01/01/70 00:00 | |
| reference | 01/01/70 00:00 | |
| Yes, but at what cost? | 01/01/70 00:00 | |
| About 4 bucks | 01/01/70 00:00 | |
| Better? In what way? | 01/01/70 00:00 | |
| 6 dollars | 01/01/70 00:00 | |
| Gee ... That isn't so bad! | 01/01/70 00:00 | |
| Tuning | 01/01/70 00:00 | |
| Hand-tuning is not cheap! | 01/01/70 00:00 | |
| Drift | 01/01/70 00:00 | |
| how does drift impact the manpower requirement? | 01/01/70 00:00 | |
| Notes | 01/01/70 00:00 | |
| Amplitude , tempco | 01/01/70 00:00 | |
| Precision | 01/01/70 00:00 | |
| Precision ... | 01/01/70 00:00 | |
| at that rate | 01/01/70 00:00 | |
| to Steve | 01/01/70 00:00 | |
| LVDT | 01/01/70 00:00 | |
| power/energy meter IC | 01/01/70 00:00 | |
energy meter IC | 01/01/70 00:00 | |
| at that rate | 01/01/70 00:00 | |
| Filtering? | 01/01/70 00:00 | |
| It will remove SOME of the distortion | 01/01/70 00:00 | |
| have you seen this? | 01/01/70 00:00 | |
| I am afraid | 01/01/70 00:00 | |
| Simple` | 01/01/70 00:00 | |
| DTMF Genarator | 01/01/70 00:00 |