Email: Password: Remember Me | Create Account (Free)

Back to Subject List

Old thread has been locked -- no new posts accepted in this thread
Zeeshan Ashraf
10/30/11 00:11
Read: 482 times
Karachi
Pakistan


 
#184440 - RE: #184439 - Separate Gain Paths - Not The Best
Responding to: Michael Karas's previous message
Thanks Michael.

Your theory is correct. However, if i use IA like AD621 that has pin-strapable gain of 100, then i reduce the chances of gain error due to Gain-resistor (resistor drift, tollerance, temperature-tracking, mismatch).

Also, if all the 4x channel circuits are within the same enclosure, theoretically all components are at the same temperature. Hence any temperature variance will affect the drift of all the components equally. Or will it be different ?

For all, here is how i am envisioning the amplifier.

Conventional amps are a single board entity with fixed 4x (or 6x in some cases) channels. My primary reason to design an amp, among other reasons, is to have a modular amp. Within this, each channel signal conditioner will be a plug-in module on a main summing board. See the attached image for the concept.

In the field, i have seen quite a few cases where 1 or 2 channels of the amp got "burned / shorted" due to various reasons, like moisture, lightning, etc. This called for a complete replacement of the amplifier AND then, re-calibration of all the load cells channels (10 or 20 turn trimpots).

In the modular concept, theoretically, if a single channel fails, only that particular channel module needs to be replaced. This reduces long-term costs and re-calibration time.

I know this is a debatable theory, might have its ups and downs, and i am wellcome to suggestions.

Regards,
Zeeshan




List of 58 messages in thread
TopicAuthorDate
Load-cell conditioning / summing      Zeeshan Ashraf      10/29/11 10:29      
   what is that?      Erik Malund      10/29/11 15:43      
      RE: #184430 - what is that?      Zeeshan Ashraf      10/29/11 15:45      
         then say what you mean      Erik Malund      10/29/11 15:53      
            your description leaves something unclear      Erik Malund      10/29/11 16:02      
               RE: #184435 - your description leaves something unclear      Zeeshan Ashraf      10/29/11 16:27      
                  where are the loadcells???      Erik Malund      10/30/11 06:08      
                     RE:      Zeeshan Ashraf      10/30/11 09:01      
      RE: #184430 - what is that?      Zeeshan Ashraf      10/29/11 15:56      
         some Q/A      Stefan KAnev      10/30/11 14:14      
            RE      Zeeshan Ashraf      10/30/11 15:27      
               Q/A 2      Stefan KAnev      10/31/11 03:00      
                  RE      Zeeshan Ashraf      10/31/11 04:18      
                     re re      Stefan KAnev      10/31/11 05:00      
                     get rid of that summing amp      Erik Malund      10/31/11 07:09      
               you will be lucky to get 16 bits      Erik Malund      10/31/11 07:04      
                  Precision again...      Kai Klaas      10/31/11 16:58      
                     Comparison      Per Westermark      11/01/11 01:12      
                     RE      Zeeshan Ashraf      11/01/11 02:20      
                        why do you keep babbling about a summing amp      Erik Malund      11/01/11 06:41      
                        Priorities...        Kai Klaas      11/01/11 07:07      
                           RE      Zeeshan Ashraf      11/01/11 07:45      
                              cirrus, ti      Stefan KAnev      11/01/11 08:42      
                                 maxim, linear tech, Analog Devices      Erik Malund      11/01/11 10:09      
                                 RE      Zeeshan Ashraf      11/01/11 17:36      
                              it takes the same time ...      Erik Malund      11/01/11 10:14      
               500 running foot of cable      Stefan KAnev      11/01/11 22:25      
                  RE      Zeeshan Ashraf      11/01/11 22:57      
                     Go for ADC with multiplexed inputs instead of multiple ADC        Per Westermark      11/02/11 07:14      
                        Good Advice      Michael Karas      11/02/11 08:00      
                           It depends...      Kai Klaas      11/02/11 08:48      
                              This is a MODULAR concept !      Zeeshan Ashraf      11/02/11 19:57      
                                 it depends      Stefan KAnev      11/03/11 00:50      
                                 don't be ridiculous      Erik Malund      11/03/11 07:17      
                                    Consider other parameters too.      Zeeshan Ashraf      11/03/11 08:16      
                                       calibration      Stefan KAnev      11/03/11 08:46      
                                       if you do not buy bootleg parts ...      Erik Malund      11/03/11 08:50      
                                          Voltage reference      Per Westermark      11/03/11 09:08      
            Accuracy...      Kai Klaas      10/30/11 16:40      
               RE      Zeeshan Ashraf      10/30/11 16:55      
                  Keep the signal paths as simple as possible.      Michael Karas      10/30/11 20:34      
                  sun umbrella      Stefan KAnev      10/31/11 03:10      
   Separate Gain Paths - Not The Best      Michael Karas      10/29/11 23:33      
      RE: #184439 - Separate Gain Paths - Not The Best      Zeeshan Ashraf      10/30/11 00:11      
         Error Budget Calculations?      Michael Karas      10/30/11 09:50      
            Hysteresis      Kai Klaas      10/30/11 10:14      
         This should alarm you!      Kai Klaas      10/30/11 09:58      
            RE      Zeeshan Ashraf      10/30/11 10:14      
               No contradiction...      Kai Klaas      10/30/11 10:22      
                  RE      Zeeshan Ashraf      10/30/11 10:40      
                     Digital Summing        Michael Karas      10/30/11 12:55      
               with DC exitacion ...      Erik Malund      10/31/11 07:20      
            welcome on board      Erik Malund      10/31/11 07:14      
      RE:      Zeeshan Ashraf      10/30/11 00:16      
   Look at ADuC845      Oliver Sedlacek      10/31/11 01:44      
      ADuC845      Russell Bull      11/16/11 20:54      
         Noise V good      Oliver Sedlacek      11/17/11 04:39      
            Ok, then      Erik Malund      11/17/11 06:26      

Back to Subject List