next topic »

[Reply #15 on:]

That reminds me of the Cold War nuclear land mine, that was going to use chickens to keep the electronics warm...

Maybe cockroaches, and a treadmill?

[Reply #16 on:]

I'm still working on getting it made a recognised SI unit

Hampshire, at the moment... until the work runs out anyway! My landlord used to do a lot of work around Crawley.

[Reply #17 on:]

There are batteries based on tritium that are supposed to (theoretically, not promised) last hundreds of years.  Just google "Nano tritium battery"

You need deep pockets though.  I think I read somewhere they were nearly $2000 each.

[Reply #18 on:]

There are batteries based on tritium that are supposed to (theoretically, not promised) last hundreds of years.  Just google "Nano tritium battery"

You need deep pockets though.  I think I read somewhere they were nearly $2000 each.

http://www.betavoltaic.co.uk/citylabs20yearnanotritiumbattery.html  these? That dip package looks so cool

[Reply #19 on:]

If the time capsule is buried in the ground then there is the possibility of using a heat pump coupled with some novel alloy and neodymium magnets?

http://en.wikipedia.org/wiki/Geothermal_heat_pump

http://www.popsci.com/technology/article/2011-06/new-alloy-can-convert-heat-directly-electricity


 

[Reply #20 on:]

The electronics could be very simple - just count equinox using the alignment of the sun (we don't have a specific date in mind), Stonehenge style.
So charging could be very low current, providing charge is greater than leakage.

Mmm, maybe that is what Stonehenge is? It will pop open soon, spouting confetti....

Or non-electronic, pure mechanical, use rise/fall of groundwater changed by tides to run a clock. Electronics could then be turned on during event day, release chemicals into a battery, and play happy birthday etc. One is only concerned with shelf-life. Bearings etc in the "clock" would only receive two 'ticks' per day, so little wear.

[Reply #21 on:]

Have a little crank on the outside of the time capsule that turns a generator and charges a battery. Put a sign that reads "Please turn crank".

Someone ought to turn it within 100 years.

On a serious note, if you can sleep your processor and it uses 0.35 uA, it would require a 306.6 mAH battery. This assumes a zero internal discharge rate, and some form of battery chemistry that can last 100 years.

[Reply #22 on:]

John, that is actually an awesome idea Crowdsourced power. The one thing you won't run out of in the next hundred years is curious people.

[Reply #23 on:]

u should go ahead with the perpetual idea

[Reply #24 on:]

I think NASA can make it.the battery that are being used in mars rovers last for almost 20 yrs.if there will be a competition,nasa will make it.

[Reply #25 on:]

The one thing you won't run out of in the next hundred years is curious people.

Reminds me of when my brother was little, he made a small wooden box with a slot in the top. He wrote "Insert Coin Here". Of course when ever we had guests over, they all had to insert a coin to see what happens 

[Reply #26 on:]

How much power is the device going to need?..  leave a solar cell, sealed up and pull it out and use it at the end of the period of time?.

or a mechanical device, a rolled up coil which releases it's energy once a year and after 100 years it triggers off lol

[Reply #27 on:]

The military uses some pretty exotic batteries that I think are supposed to have near-forever shelf-life (well, 20 years, anyway.)  In missiles and fuzes and things.  They're essentially solid and inert at room temperature and need to be activated by a pyrotechnic charge to melt the relevant parts.  After which they produce plenty of power, for long enough for the device to reach the target.   http://en.wikipedia.org/wiki/Molten_salt_battery

Come to think of it, there's a slightly similar class of water-activated batteries, and a near equivalent in the zinc-air batteries commonly used in hearing aids.  I suspect that if you can build a storage container that will hold vacuum for 100 years, a circuit with OTS Zinc-air batteries might still work after 100 years once you let air (and moisture) in.

[Reply #28 on:]

-snip-

But how do you figure out when the 100 years is up so you can trigger the battery? What triggers the battery?

[Reply #29 on:]

-snip-

But how do you figure out when the 100 years is up so you can trigger the battery? What triggers the battery?

Another molten salt battery. To trigger that battery you'd just use another molten salt battery.... and then eventually a turtle.