Silent radio Sign Part 2

The Silent Radio LED sign is proceeding along nicely so far. I have decided on using an Arduino for the processor to run it.

I have tested the power supply and column driver transistors, the are all working so far.

The biggest problem so far is that the driver transistors run really hot. That is because they are half way on with 5 volts on their base and 9 volts on their collector they have to drop the difference of 4 volts at many Ma thus producing a lot of heat. A different driver circuit would cure that by turning the drivers all the way on but that would feed 9 volts to the LED array and that might be a bit too much.

Here is an updated schematic.

The next step is to get the Arduino serial and clock to connect to the signs serial and clock to send actual data to the sign.