Chris Hogg was thinking very hard :
I made one or two Heathkit things - the digital clock comes to mind,
one of these https://tinyurl.com/y6afaer6, except that whenever the
mains went off, it needed re-setting, so I added a 50cps oscillator
and battery back-up.

I bought and built one of those, I took a special trip down to London
to collect the kit direct from Heathkit. It was still working around 15
years ago, when I decided to bin it - I wish I'd kept it now.