SIM racing three coloured flags from two inputs, such as RTS & DTR on COM port. The PCB has a 6pin SIL header to plug in a CP2102 USB to serial adapter. It uses a binary to decimal converter to make use of two digital inputs and convert them to three separate FET's outputs to drive LED circuits for three colours
The PCB design also accepts an optional external DC power socket and screw terminal blocks so you can operate relays and such to control higher current LEDs (strips for eg.) or other output devices. I based it on a box size I had at hand for which I mounted a lightpipe in to view the front edge.
Pictures to be added soon.