Julian Posted February 1, 2005 Report Share Posted February 1, 2005 hello,i used the reichelt st led for my seq, but especialy the blue ones are much too bright! can't read the panel anymore when the seq is turned on ;is it possible to add a resistor before the dout module, to ower their brightness?or is there any better way?best,julian, Quote Link to comment Share on other sites More sharing options...
seppoman Posted February 1, 2005 Report Share Posted February 1, 2005 You can either put an additional resistor between DOUT and the LED, or you could simply change the 220 Ohm resistors on the DOUT for some of higher resistance. Higher resistance -> less current -> less brightness. Just don´t replace the DOUT resistors by "smaller" ones!If you want to calculate the current:I = (5V - UL) / RUL is the forward voltage of the LED. Standard types have around 1.5 V, blue and extra-bright LEDs often have more (2-4 Volts). The standard resistance of 220 Ohms gives (5V-1.5V)/220 = 16 mA of standard LEDs, which usually is a good value.Replace them e.g. with 500 Ohm resistors and you´ll get 7 mA.Seppoman Quote Link to comment Share on other sites More sharing options...
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