For the first time I am going to make a digital clock with 7 segment displays with Arduino Multiplexing. I am about to use the following circuit to run 4 large Common Cathode 7 Segment LED Digit Displays. The circuit diagram shows only 2 digits with 4 of their anode pins connected. Hope you understand the full schematic from this diagram.
– Schematic created using CircuitLab
My Questions are:
- Is this schematic correct?
- These are large 4 inches displays, run on 9V, Common Cathode type and consumes approx 200mA current total for all eight segments of each display. Programmatically, I am going to multiplex digit by digit, not segment by segment. Do you think BC337 is the right choice for this, considering in parallel that I will turn the digits on and off as frequent as once every 1 mS?
- Base resistors 1K Ohm. Is the value ok to supply enough current to transistor base and lit up the LEDs with Arduino's digitalWrite(Dn, HIGH) method?