This is a 3 Digit 7-segment display project that contains 3 x Common Cathode displays, current limiting resistors or each LED segment, 3 x PNP Transistor on each common cathode for multiplexing etc. The project works with 5V TTL signals but can be optimized for 3.3V operations by reducing the current limiting resistors’ value. A header connector is provided for easy interface to Arduino or other microcontrollers. All inputs are TTL 5V compatible.
3 Digit Common Cathode 0.5″ – 7 Segment Display Module (Multiplexed) – [Link]