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

Back to Subject List

Old thread has been locked -- no new posts accepted in this thread
Kai Klaas
02/14/06 19:21
Modified:
  02/14/06 19:40

Read: 579 times
Germany


 
#109995 - Include R8 in the feedback loop
Responding to: Farshid Jafari Harandi's previous message
Do never connect a capacitor directly at output of an OPamp. This will cause instability and oscillation. So, if you remove C6, the 'noise' should disappear.

Potential at C20 is not constant but demonstrates that C20 is relevantly charged and discharged. This is a sign, that C20 is not big enough.
One remedy is to increase C20. But much better is to include R8 in the feedback loop, like it's shown in figure 6 of this datasheet:

http://www.analog.com/UploadedF..._413_e.pdf

Keep everything unchanged, but include R8 in the feedback loop and add a 100nF cap (like C1 in figure 6) and a 10k resistor (like R3 in figure 6). R8 can be decreased to 100R. C20 should be a good tantal.

Kai

List of 21 messages in thread
TopicAuthorDate
DSO's Op-Amp adder probelm :(      Farshid Jafari Harandi      02/14/06 11:41      
   Looks ok but i am missing something      Jez Smith      02/14/06 15:14      
   By the way...      Jez Smith      02/14/06 15:26      
      Answers      Farshid Jafari Harandi      02/15/06 03:41      
   I just had a thought      Jez Smith      02/14/06 15:37      
   Include R8 in the feedback loop      Kai Klaas      02/14/06 19:21      
      C6 ?      Farshid Jafari Harandi      02/14/06 20:59      
         Good idea      Kai Klaas      02/15/06 05:59      
            Pictures      Farshid Jafari Harandi      02/15/06 07:07      
               Congrets!!      Kai Klaas      02/15/06 07:54      
                  RE : Congrets!!      Farshid Jafari Harandi      02/15/06 08:26      
                     Prototyping      Kai Klaas      02/15/06 08:50      
      Corrections      Farshid Jafari Harandi      02/15/06 04:54      
         Developing      Kai Klaas      02/15/06 05:58      
            Time matters !      Farshid Jafari Harandi      02/15/06 06:56      
               some "friend"      Erik Malund      02/15/06 07:02      
                  Imagine !      Farshid Jafari Harandi      02/15/06 07:18      
               AC setting?      Kai Klaas      02/15/06 07:50      
               Obey??      Kai Klaas      02/15/06 07:52      
               Tricky      Kai Klaas      02/15/06 07:57      
   What if...      Kai Klaas      02/15/06 08:57      

Back to Subject List