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

Back to Subject List

Old thread has been locked -- no new posts accepted in this thread
???
02/29/12 22:30
Read: times


 		 #186301 - And another thing...
Responding to: ???'s previous message
Apart from all the other truly horrible things about this, you can't just use a 470-ohm resistor with a 72-LED chain!!

When you use 1 resistor with 1 LED in a "normal" low-voltage circuit, the resistor has a significant effect on the current through the series combination; but one 470-ohm resistor in ~280V has negligible effect!!

As already noted, this is a stupendously Bad Idea!

If you really must have mains-driven LEDs, then get a proper power supply for the purpose; or, at least, use one of the many chips that are specifically designed for this purpose...

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      

Back to Subject List