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Suresh R
02/13/06 02:42
Read: 597 times

#109827 - issues
Responding to: Kai Klaas's previous message
Kai Klaas said:

Q4 provides a soft-start, means a slow turn on of LM338.

I think its due to the RC network connected to the base of Q4. Hence the impedence of the adj terminal towards ground decreases with increase in cap charge.Is it so.

kai klaas said:

by the help of suited feedback, the voltage at output of U2B also appears as voltage drop across R12. This voltage drop is caused by the current of constant current source. Output of U2A controls Q2 and by this Q3, so that the voltage drop across R12 always equals the potential at non-inverting input of U2B.

Is this power dissipation in R12 needed or can i remove it.

Also in the regulator part,
The adj current is equal to the current flowing through the current set resistor - R7(120E). How the power rating could be calculated for this resistor.
The presently running one has a R7=120E/.25W and is working well.

For instance let me assume that the regulator delivers 2A at 6V to the load. for this voltage value, how the power rating of R7 will be calculated.
Terry Lingle said:

(this lacks solution temperature feedback for example)

The temperature of the plating bath will be at 65 degree celsius.
Will this need to be taken into account for setting the current. will the load experience any additional current due to this temperature effect.

Terry Lingle said:

all the 338 circuit does is remove most of the ripple on the input supply and thus improve the current regulation. It also shares the power dissapation with the mje3055.
it dissapates most of its power across the regulators rather than the load.

Is the buck regulator proving main cause of power dissipation?
I would like to know how, more power is being dissipated in the regulators and mje3055 referring to my circuit.


List of 21 messages in thread
3A constant current source      Suresh R      02/11/06 04:41      
   Where did you find it?      Andy Neil      02/11/06 05:56      
   Ripple      Andy Neil      02/11/06 06:00      
      plating purpose      Suresh R      02/11/06 09:45      
         I got it from a person known to me      Andy Neil      02/11/06 15:04      
            replies      Suresh R      02/12/06 09:24      
               plating circuit      Terry Lingle      02/12/06 11:40      
                  Compliance of source      Steve M. Taylor      02/12/06 13:51      
                     yes      Terry Lingle      02/12/06 16:21      
         Think about that      Neil Kurzman      02/11/06 16:08      
   Component Purposes      Bruce Bailey      02/11/06 12:58      
   This circuit will never work!      Kai Klaas      02/11/06 19:46      
      Could it be?      Neil Kurzman      02/11/06 23:55      
         Function      Kai Klaas      02/12/06 20:08      
            issues      Suresh R      02/13/06 02:42      
                plating quality control.      Terry Lingle      02/13/06 07:29      
               Answers      Kai Klaas      02/13/06 11:36      
                  followups      Suresh R      02/14/06 02:20      
                     Answers II      Kai Klaas      02/14/06 07:01      
                        followups & Back EMF's?      Suresh R      02/15/06 03:59      
                           Floating regulator      Kai Klaas      02/15/06 09:27      

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