Hi,
Thanks for the clear schematic, can you export it as a jpg rather than a pdf.
And it can then be put in the post as in image.
What does Q2 do?
Disconnecting the GND of the regulator will not turn the regulator ON or OFF.
What sort of accuracy and resolution are you trying to attain for a kitchen timer?
You could have used an RTC and then just used one UNO and software to load, display and monitor variables.
What are you using for a power supply?
Thanks.. Tom.. 