I've looked into various options for LED colors for the clock. I've ordered some green LEDs to try. They're going to arrive this week - my wife requested green, so she gets a special one.

The next color to try was going to be blue, but there's a problem. LiteOn does make blue modules, but they have a 3.8v forward voltage. That means that the display subsystem will need to run on 5 volts instead of 3.3. That means dramatically changing the circuit. The GPS receiver still needs to run on 3.3 volts. The PPS and serial output can still be fed into a controller running at 5 volts, but it means that you can power the GPS module alone with just an LDO. There's no need for the buck converter, since the whole rest of the system can run directly from the 5 volt input.

But all of that requires a whole new board design... It's just not worth the bother.

At the same time, however, I've designed a new variant of my GPS Disciplined Oscillator project. That variant is going to have a mini-DIN 6 diagnostic connector which will provide the GPS serial and PPS output and +5 volt power. That means that the clock can be recast as a peripheral for the GPSDO. Of course, for maximal stability, you need to plug the clock in and leave it - sudden load changes on the power bus aren't great for the stability of the oscillator - but that said, it should work just fine. In principle, you could supply NMEA serial data and PPS pulses from nearly any other GPS source with such a board.

I've already ordered boards for the "peripheral" variant, but I'm not sure I'm going to add it to the store or not.