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LED Current Limiting Strategy

neilbaldwinneilbaldwin
edited July 2014 in Technical details and features
OK, so I assembled my latest build with the intention of using different LEDs but I installed the 'normal' current limiting resistor networks (220R) and now I need to pull the current down even further.

I've tried experimenting with a pot across one of the RLED connections but the behaviour seems peculiar - seems no matter what value pot I use I can't add enough resistance to get the LED brightness down. Is this a peculiarity of the bright LEDs (they're 'warm white' 750mcd)?

I was also wondering if there's a 'clever' way of maybe reducing the current going into/out of the LED driver ICs so that I could drop the current with just one added resistor per resistor network instead of having to install all 39 of the RLEDs.

Or, ultimately, am I going to just have to bite the bullet and desolder the 220R networks and replace with a higher resistor value?

Comments

  • julianjulian
    the R_LED resistors are in paralell with the networks. So you use either or.
    adding additional resistors to R_LED wil always decrease the 220ohm from the network.

    so either remove the networks (clip off GND connection on pin 1)) and put in higher value R_LED resistors. Or remove the resistor networks completely and replace them with a higer value network.
  • neilbaldwinneilbaldwin
    Ah, makes sense now Julian. Thanks.
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