How do I make an led display that counts down in seconds until my 70th birthday. Currently 17344800. Can anyone help?

I am an artist currently exploring the value of time and have a piece I wish to build entitled 'every second counts'. I need to make a timer that counts backwards in seconds from a large number, but don't have the skills to modify what I can already find on the web.
I would really appreciate some help here.

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Not easy without the electronics skills, but you can start out with some simple CMOS logic gates, like the 4510 up/ down Decade counter chip, and add some 4511 decimal to 7 segment decoders, and a bunch of  low current high efficiency 7 segment displays.

Make a simple crystal clock, plenty of circuits out there. - use a watch crystal and a pair of 4060 divider chips to get a nice 1 second pulse. 

I can sketch some more circuit if it'd help ? 
TomFreer (author)  steveastrouk7 years ago
Awesome. Thanks for that...sounds like you know more about electronics than is strictly healthy! (not being mean - respectfully in awe)
I think that my electronics knowledge might be too basic to attempt this. I know that it must be possible to get the effect I am after, but not without either four years+ of studying and practice or a huge amount of help such as someone designing and building the circuitry (or at least explaining it in baby steps).
I would ask for sketches if I thought it would help, but how much time can one person spare?
In addition I missed out that I actually want it to countdown in tenths of a second, which will give the piece more movement and therefore more urgency that time is running out...
Here's a PDF of the counter bits. For every digit in your clock, you need two chips, you can see how they all link together. If this isn't too daunting, I'll add an oscillator to drive it, and some way of setting it !<br /> <a href="http://www.thetaylorfamily.org.uk/Instructables/counter.pdf">www.thetaylorfamily.org.uk/Instructables/counter.pdf</a><br />
Sandisk1duo7 years ago
if you have a really old computer, you can find a counter on the internet

yo uwill need a computer screen
TomFreer (author)  Sandisk1duo7 years ago
Thanks for that, I did think of using a computer as a solution but then ruled out using a screen... the look I'm after is a multi LED matrix (in green on black background)