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
|Green||SMD LED grn 100mcd Gullwing ZD2010 9061||25.0mA||2.2V
|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).