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???
06/13/09 07:43
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 		 #166046 - Doesn't it show that he's missed an important point?
Responding to: ???'s previous message
Quite so.

But doesn't it go to show that he's missed an important point about the ULN - or any other - driver?
(viz, the additional voltage drop that it introduces)

His specific question was why the LED was dimmer with the ULN driver than without it. Understanding why this is so would also help to understand why a proper constant-current drive is so much better.

Wouldn't it?

List of 30 messages in thread
TopicAuthorDate
High power led driver            01/01/70 00:00      
   Have you accounted for Vce(sat) ?            01/01/70 00:00      
   resistors are not a good solution            01/01/70 00:00      
      Have you considered a current mirror?            01/01/70 00:00      
         mirror, mirror on the wall            01/01/70 00:00      
            No question about it ...            01/01/70 00:00      
               But was that the question?            01/01/70 00:00      
                  I focused on the brightness match ...            01/01/70 00:00      
                     Doesn't it show that he's missed an important point?            01/01/70 00:00      
                        He doesn't really have to consider voltage            01/01/70 00:00      
                           for a (short) while            01/01/70 00:00      
   Sorry for the delay            01/01/70 00:00      
      The ULN works perfectly well - as far as it goes.            01/01/70 00:00      
      MOSFET Technical Info            01/01/70 00:00      
      Key term is 'logic level'            01/01/70 00:00      
         commom part            01/01/70 00:00      
            Catalogue?            01/01/70 00:00      
   Mosfet            01/01/70 00:00      
      I believe you'll have a problem ...            01/01/70 00:00      
         IRF530            01/01/70 00:00      
            Dig a little deeper, Chico ...            01/01/70 00:00      
               circuit... will work if I do this way?            01/01/70 00:00      
                  No!            01/01/70 00:00      
                  Look at the specification for IRLD120            01/01/70 00:00      
                     now i get confoosed            01/01/70 00:00      
                        High power            01/01/70 00:00      
                        He has digressed            01/01/70 00:00      
                           I suspect it's because he needs a constant current switch            01/01/70 00:00      
                              And I suspect that we are wildly guessing...            01/01/70 00:00      
                                 a little more specificity, please, Chico            01/01/70 00:00      

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