Testing is done for now. Quick synopsis (TL;DR), don’t get rid of the resistor if you want batteries to last. I tested with the full PWM values from 1-255 and then halved them to range from 1-128 (see chart 1). I quartered them as well but ended up not using it because the half ended up disappointing.
Chart 2 shows the average current versus the resistor value for the different PWM values.
Lastly in Chart 3, I measured the light output of the LED. If anyone cares, using a Sekonic L-508 spot meter.
What this is showing is that no matter which resistor value (or no resistor) you pick when using a lower output PWM, it will never match the light output of the full range PWM values with the existing 220 ohm resistor.
Bottom line, if you want to keep the same quality of light output, you can’t change the PWM to a lower duty cycle.
Oh man this is the best post ever. LOOK AT THOSE GRAPHS! CHECK OUT THAT DATA!
Adafruit publishes a wide range of writing and video content, including interviews and reporting on the maker market and the wider technology world. Our standards page is intended as a guide to best practices that Adafruit uses, as well as an outline of the ethical standards Adafruit aspires to. While Adafruit is not an independent journalistic institution, Adafruit strives to be a fair, informative, and positive voice within the community – check it out here: adafruit.com/editorialstandards
Stop breadboarding and soldering – start making immediately! Adafruit’s Circuit Playground is jam-packed with LEDs, sensors, buttons, alligator clip pads and more. Build projects with Circuit Playground in a few minutes with the drag-and-drop MakeCode programming site, learn computer science using the CS Discoveries class on code.org, jump into CircuitPython to learn Python and hardware together, TinyGO, or even use the Arduino IDE. Circuit Playground Express is the newest and best Circuit Playground board, with support for CircuitPython, MakeCode, and Arduino. It has a powerful processor, 10 NeoPixels, mini speaker, InfraRed receive and transmit, two buttons, a switch, 14 alligator clip pads, and lots of sensors: capacitive touch, IR proximity, temperature, light, motion and sound. A whole wide world of electronics and coding is waiting for you, and it fits in the palm of your hand.
Have an amazing project to share? The Electronics Show and Tell is every Wednesday at 7pm ET! To join, head over to YouTube and check out the show’s live chat – we’ll post the link there.
Fun investigation, cool. 🙂