Clock Hands as Input?

I'm designing an installation where I'd like the environment to change based on the position of the hands of a clock. Think of the grandfather clock in Wayne Manor that opens into the Batcave when the hands are set to the time of Batman's parents death.

While I have a good grasp of how I would use the input, I'm having some trouble conceiving of a mechanism to read the position of each hand at any given time. In terms of skillset I'm a decent coder and making good progress in my understanding of electronic components and principles.

Hopefully this is the right forum and my first post isn't too embarrassing!

put 2 magnets behind the hands (on different length from the central axis) and put hall sensors behind the numbers plate on the wanted position.

Nice! That sounds simple, especially if I only need to trigger off a single hour/minute combination. The solution I was looking at last night involved opto-mechanical sensors from old ball mice, but that would be a lot more complicated mechanically. Plus there's the whole calibration issue...

Thanks for the reply and the advice!

Please let is know when you got it working - exhibition section or this thread !

Maybe one of these with a rotary encoder attached to the gear(s)?

Okay.. if i was you i would have solve this on in other way. I will be using simple RTC with Arduino and will make it sure that the clock and RTC never go wild :)... I would have used RTC to controll the environment...

I will agree with Khalid on that one.

A simple wall clock and a cheap DS1307/DS1337/DS3231 will keep really accurate time over half a year span with no problems. How long are your installation going to run ? Anyway, the RTC will be way more accurate than the mechanical clock, so once you set the RTC, you won't need to worry about that anymore, just adjust the mechanical clock to accurate time once in a while, if you are not satisfied with it's accuracy.

// Per.