To make sure I supply the right amount of voltage for my Wemos D1 mini projects I need to know a little bit more about the kinds of LEDs I intend to use.
With the Wemos D1 mini typically supplying components with 3.3 V, I need calculate the approproate resistors for my various SMD LEDs.
An online web app (“LED Resistor Calculator,” n.d.) was very handy to find the right values. Below is a table of all the LEDs I have in my stash and the most important values from their data sheet for easy reference.
| Type | If | Vf (max) | R 3.3V | |||
|---|---|---|---|---|---|---|
| Red | SMD LED red 70mcd Gullwing ZD2000 9061 |
30.0mA | 2.0V (2.5V) | 43 Ω | 43Ω | (Datasheet) |
| Yellow | SMD LED yel 40mcd Gullwing ZD2005 9061 | 30.0mA | 2.1V (2.5V) |
40 Ω | ||
| Green | SMD LED grn 100mcd Gullwing ZD2010 9061 | 25.0mA | 2.2V (2.5V) |
44 Ω | ||
| White | SML-LX1206UWW-TR LED, QuasarBrite, White, SMD | 20.0mA | 3.5V (4.0V) | – | – | Datasheet |
Below is an image of how I use my coloured LEDs for the visualisation of water temperature in combination with resistors on a copper tape paper circuit (inspired by Qi, 2012 and High-Low Tech Group, MIT Media Lab, 2012).
High-Low Tech Group, MIT Media Lab. (2012, August 21). Paper circuits. Retrieved February 27, 2019, from http://highlowtech.org/?p=2505
LED Resistor Calculator. (n.d.). Retrieved February 28, 2019, from http://www.ohmslawcalculator.com/led-resistor-calculator
Qi, J. (2012). The Fine Art of Electronics: Paper-based Circuits for Creative Expression (Master of Science in Media Arts and Sciences). Massachusetts Institute of Technology, Massachusetts, NE. Retrieved from http://web.mit.edu/~jieqi/Public/Jie_Qi_MS_thesis.pdf