I have one panel of my project that will consume 5.34 amps when I turn on all indicators using a TEST button. These are all standard LEDs, 7-segment LEDs and 14-segment LEDs; assuming 20mA each LED using 330R resistors and 5 VDC. I counted each segment as an individual LED in my tally.

My plan is to use PWM and transistors to decrease current consumption. Is there a quick rule of thumb that I can use to get a general idea on what to expect?

Or can I PWM a single LED, check the current and use that as new baseline instead of 20mA? Or is there more going on when hundreds of LEDs are involved with PWM?

Robert "The PWM Noob"