I have two seven-segment displays. Each display requires about 12 V to power and each segment of the display needs about 20 mA (so about 140 mA worst case scenario).
I have everything working if I power the microcontroller and displays independently with two different power supplies, but when I try to run both off of one power supply, the displays are extremely dim and some of the segments won't even turn on. The power supply I'm trying to use outputs 12 V, 2A (outputs 14 V in practice).
Why isn't this working? Do I just need a power supply that can provide more current? The microcontroller supposedly draws about 170 mA max, and the displays would draw about 280 mA worst case scenario. That's well under the 2 A my power supply provides. What am I missing here?
Here's the schematic of my circuit. I apologize it's so messy. There may be a mistake with the transistors but it's only in the diagram; that part works correctly in the circuit itself. This is my first go around with making circuits in software.