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02/29/12 05:58
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#186270 - AC Powered LEDs + strobe
Hello.
I want to make a LED light powered from AC without supply...
Yes, I know it is dangerous...

Firstly, I thought in using a long series of LEDs to achieve around the 280V peak then a "small" resistor.
I found this circuit in the google:

I will use just one LED series.
I want to know what does the first pair of capacitor (in the input, before the bridge), can someone explain me please?
(Looks like I can use ONE non polarized capacitor in the input and ONE polarized capacitor after the bridge).
I will use 1w pure white LEDs, 350mA, around 3,8v each.

Secondly, I want to turn this in to a strobe, I want to control it with a microcontroller by DMX.
I would need some help in how to switch this securely.
I dont care if microcontroller blows or even the LEDs, but there could be another DMX devices and it is not nice to burn then all.
I thought to use something like an IRF840 (switches much more than 280v) after the retificator, so when LEDs are off the capacitor will be charged, when turned on it will discharge the capacitor to the LEDs...

Maybe I'm saying much wrong things here, please dont be to severe.

Thank you.


PS: This is for my own use, not comercial.

List of 27 messages in thread
TopicAuthorDate
AC Powered LEDs + strobe            01/01/70 00:00      
   Isolated Switch            01/01/70 00:00      
      Switching            01/01/70 00:00      
   Some basics            01/01/70 00:00      
      Not a good design - and expensive            01/01/70 00:00      
         Answers + need some explantion            01/01/70 00:00      
      Cap voltage            01/01/70 00:00      
         More than 280V            01/01/70 00:00      
            Measurement            01/01/70 00:00      
               Measurement correct            01/01/70 00:00      
   two caps polarity reversed on DC!! ?            01/01/70 00:00      
      More common long time ago            01/01/70 00:00      
         I was around then            01/01/70 00:00      
            Some polarized capacitors survives AC but not reversed DC            01/01/70 00:00      
               POOOOOOOOOF            01/01/70 00:00      
                  Yes, very likely a failure            01/01/70 00:00      
                     that need bold face            01/01/70 00:00      
            Back to back connection...            01/01/70 00:00      
   And another thing...            01/01/70 00:00      
      Pseudo-CC with resistor requires much % V over resistor            01/01/70 00:00      
      chip            01/01/70 00:00      
         one of these            01/01/70 00:00      
         Chips            01/01/70 00:00      
   PC PSU            01/01/70 00:00      
      Definitely better with lower voltage design            01/01/70 00:00      
         PSU            01/01/70 00:00      
            Some bricks can inform about rating            01/01/70 00:00      

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