I connected the clap sensor on the slate to a spare pin on the TCG microprocessor,(Red phono lead) and told the TCG to freeze the display when the clap arm was closed. Closing the clapper many times, it seems as if the slate is running slightly fast, maybe 1/4 to half a frame after 8 hours. About what was expected.
The software that does nanotweaks to compensate for any basic crystal oscillator offset was not enabled. Workshop temperature was about 23C. The whole thing was run on a 5V bench power supply, since the slate display was on all the time, I didn’t think the internal 4 AA batteries would last overnight.
Pretty good for a less than 5€ TCXO.
12 hours in, still under 1 frame fast, that’s about 1 part per million accuracy