??? 08/16/04 06:30 Read: times |
#75949 - RE: construction of marix Responding to: ???'s previous message |
hi,
4. i will put the current limit resistors at the anodes of the LEDs (i.e. one resistor for the input point of each row. Bad idea. Put resistors exactly as they are drew at that schematic above. Here: one resistor per column. It is because if you use refresh by the rows then only one LED in column may light at time. And so its current will be limited constantly. In case you put one resistor per row then it will not be possible to limit current constantly. It is because the couple of LEDs (or even all LEDs of row) may light simultanely and so current through row limit resistor is not constant value - it depends on the number of light LEDs. As result, than more LEDs are lighted than less bright they have. As well, as Kai said, you should select more high current due LEDs are multiplexed and so it is duty presented. Regards, Oleg |