Build report 6.0

A project log for GPS Clock

A simple desk clock that gets extremely accurate time from GPS

nick-sayerNick Sayer 11/03/2019 at 06:180 Comments

The version 6.0 boards are a success.

I built one with red LEDs and it's quite good. It's a touch dimmer than 5.0 was, but I think that's overall a good thing - the versions up to now were a little too bright insofar as the low end of the brightness range was still too bright. With the per-segment 30 mA current limit there is absolutely no brightness variation of the AM/PM LEDs when the colons blink, which was a small issue before. There's no trace of ghosting with the 1 kΩ pull-downs on the anodes (though to be fair it wasn't an effect that was noticeable with red anyway. I'll build a blue one and then we'll see).

Moreover, it works normally even with 9 volts supplied on the input power (thanks to the wide-input LDO for the 3.3v rail). The LDO did start to get a bit warm, however, and this was with the antenna disconnected, so it wasn't supplying any antenna power. This means that the board could conceivably be used as the brains behind very large displays where the Vf of the segments is much higher.