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

Back to Subject List

Old thread has been locked -- no new posts accepted in this thread
???
11/30/11 15:30
Read: times


 		 #184959 - Numbers...
Responding to: ???'s previous message
The following scope plot shows the voltage drop of a mains transformer's primary current across a 1R shunt resistor:



It's a stiff TALEMA 25VA ring core mains transformer loading a total capacitance of 4500µF. The caps carry a voltage of 25,8V and deliver an ohmic current of 350mA. So, 9W is delivered by the transformer.

9W corresponds to a resistive load of 5880R at mains, meaning a current of 39mAeff, or 55mApeak. The above transformer draws a mains current of 110mApeak, which is only twice the current of a perfect ohmic load!

Kai Klaas

List of 26 messages in thread
TopicAuthorDate
a myth debunked ?            01/01/70 00:00      
   Same old?            01/01/70 00:00      
   Hhm...            01/01/70 00:00      
      no, I did not            01/01/70 00:00      
         Babble of marketing people...            01/01/70 00:00      
            read it all            01/01/70 00:00      
               There's no need for HF-ripple rejection...            01/01/70 00:00      
               ... what's more important ...            01/01/70 00:00      
                  whatever            01/01/70 00:00      
                     But the article claims it...            01/01/70 00:00      
                        even the article states            01/01/70 00:00      
                           Switchers ARE beautiful...            01/01/70 00:00      
                        do linear regulators ever "produce" ripple?            01/01/70 00:00      
                           getting more and more irrevelant            01/01/70 00:00      
                              Perhaps, but where else would ripple originate?            01/01/70 00:00      
                                 still missing the point            01/01/70 00:00      
                                    Why do you see this as "becoming more mandatory"?            01/01/70 00:00      
                                       you can't do PFC without            01/01/70 00:00      
                                          Vice versa...            01/01/70 00:00      
                                             Not so fast            01/01/70 00:00      
                                          fortunately, PSU's are not on my deliverables list            01/01/70 00:00      
                                       I'm with Eric            01/01/70 00:00      
                                          Disadvantage of switched-mode supplies...            01/01/70 00:00      
                                             Huge crest factor            01/01/70 00:00      
                                                Numbers...            01/01/70 00:00      
                           It depends on load            01/01/70 00:00      

Back to Subject List