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Farshid Jafari Harandi
08/19/05 10:02
Read: 447 times
Sweden
Gothenburg


 
#99705 - Current regualtor
Responding to: Erik Malund's previous message
You're right , current limited source is better , here is my schematic , what's your opinion about this :


As the output of LM317 current controller is open , output capacitor The 47uf would charge to Vcc-1.2v .
after firing the Q1 that capacitor would give a big shock to the led for a very short time (i think it would be good to make it turn on fast) and then LM317 would take the control throught the loop ,lowering the voltage to reach the correct voltage for the 250mA regulated current source.
And the RC in the input of the 2N2222 would lengthen the short shock from the pickup transformer to something about 1 ms ?.
Is it better to use a FET (Lower on resistance and faster turn on) instead of 2N2222 ?

I'm planing to use some 5mm high intensity LEDs in parallel , or use some big 10mm's or power diodes.

List of 45 messages in thread
TopicAuthorDate
Tachometer and engine timing tool      Farshid Jafari Harandi      08/13/05 22:06      
   Engine analyser      Russell Bull      08/13/05 22:44      
      RE : Engine analyser      Farshid Jafari Harandi      08/14/05 12:19      
         Engine analyser      Russell Bull      08/14/05 19:11      
            Xenon Flash Lights      Farshid Jafari Harandi      08/14/05 20:50      
               Xenon flash lights      Russell Bull      08/14/05 21:39      
                  Calculating RPM      Dan Adams      08/15/05 07:38      
                     RE: Calculating RPM      Farshid Jafari Harandi      08/15/05 14:10      
                  flash charge circuit      Farshid Jafari Harandi      08/15/05 14:16      
   Look at this then        Steve M. Taylor      08/14/05 07:15      
      I like it...      Farshid Jafari Harandi      08/14/05 12:20      
   Xenon      Neil Kurzman      08/14/05 16:51      
      Delay time < 10us      Farshid Jafari Harandi      08/14/05 20:31      
   Led Instead Xenon        Roberto Muņoz      08/17/05 08:02      
      Interesting idea, were I to make sutch a      Erik Malund      08/17/05 08:08      
         White is better for finding the TDC mark      Farshid Jafari Harandi      08/17/05 14:13      
            If white light is required and what I ha      Erik Malund      08/18/05 06:08      
               Good link      Farshid Jafari Harandi      08/18/05 14:07      
      Nice !!      Farshid Jafari Harandi      08/17/05 14:08      
         I do not work with white LEDs but with r      Erik Malund      08/17/05 14:30      
            White LED      David Smith      08/18/05 07:01      
               got curious and googled      Erik Malund      08/18/05 07:12      
               got curious and googled      Erik Malund      08/18/05 07:13      
               Hmm      Steve M. Taylor      08/18/05 07:35      
                  Sure it's not, but      Farshid Jafari Harandi      08/18/05 14:07      
                     New prototype circuit      Farshid Jafari Harandi      08/19/05 01:07      
                        I would recommend a constant current cir      Erik Malund      08/19/05 06:05      
                           Current regualtor      Farshid Jafari Harandi      08/19/05 10:02      
                              C2 may blow your LED, what is it there f      Erik Malund      08/19/05 11:19      
                              Led ON time      Russell Bull      08/19/05 22:51      
                                 6000 RPM      Farshid Jafari Harandi      08/20/05 12:42      
                                    6000RPM      Stuart Hall      08/21/05 01:06      
                                       Can't comment on that now      Farshid Jafari Harandi      08/21/05 14:30      
                  saw an article and while this probably      Erik Malund      08/18/05 14:12      
                     Thanks      Steve M. Taylor      08/18/05 14:33      
                        timing light      Russell Bull      08/18/05 23:09      
                           unanswered questions      Farshid Jafari Harandi      08/19/05 01:06      
                  White LED v Xenon tube      David Smith      08/19/05 01:19      
                     'difficult' to drive      Farshid Jafari Harandi      08/19/05 04:25      
                        Big LEDs      Steve M. Taylor      08/19/05 04:57      
                           So Thats it !      Farshid Jafari Harandi      08/19/05 09:59      
                              Who has said ir has to be just one, can      Erik Malund      08/19/05 11:21      
                                 C is for stability ?      Farshid Jafari Harandi      08/20/05 12:32      
                     I have no idea, but I have seen I do not      Erik Malund      08/19/05 06:13      
                        White LED 'drivers'      David Smith      08/20/05 14:31      

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