You can control the brightness of these LEDs using variable resistors VR1, VR2 and VR3 respectively. Parts Needed. Arduino UNO board – 1 ; 5mm LEDs Red, Green, Blue – each 1 ; 100K Variable resistor – ...

so tinkercad has circuit designand arduno now, a real arduino is $20, IDE is free, fritzing is free and does all the exact same layout stuff locally, you save your files and keep them forever.

Here is a simple, yet useful circuit of an Arduino 4-digit 7-segment LED display unit. The module used here is a self-contained, compact common-cathode module containing four 7-segment LED numeric ...

His test circuit uses six 2N2222 transistors to protect the Arduino from excessive current. You can see six red LEDs above which are inline with the base of teach transistor.