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Erasing CDs By Using 150,000 Volts of Electricity
ryzvonusef writes "One enterprising individual has created the most secure way to wipe out Compact Discs, by using a step-up transformer and creating a 150,000 Volt pd, whilst a CD rotates in the middle. The sparks arc through the metal in the CD and evaporates it, ripping it all off as the CD rotates. The CD is rendered transparent and unreadable. This may be the most secure method to remove data on conventional recordable CDs used in offices."
Science geeks have been doing this for years with microwave ovens; though, it was more for the cool light show than for data security.
Try to imagine all life as you know it stopping instantaneously and every molecule in your body exploding at the speed of light.
That... was one of the coolest electricity displays I've seen in a long time.
Ta heck with what it does, lol
-AI
For me, it is far better to grasp the Universe as it really is than to persist in delusion
I've done it dozens of times. My 13-year-old cheapo microwave oven didn't bat a lid. Still going strong.
I think the "easy to damage the microwave" is an urban legend. Someone should submit it to Mythbusters.
I hadn't known there were so many idiots in the world until I started using the Internet -Stanislaw Lem
Of course you can not read a CD if the reflective metal layer is removed. But the data is stored in tiny pits that are printed into the polycarbonate layer. If the polycarbonate is not damaged too much, the CD might be readable when a new metal layer is applied.
The most secure way to destroy CDs is either dissolving in acid or loaning them to my boss. I promise, you'd never see it again.
It's not an intuitive thing, don't worry you're not alone in not immediately seeing the problem.
A magnetron is a kind of RF (radio frequency) transmitter. It converts electrical energy into radio energy. This energy leaves the magnetron and bounces around inside the microwave. The frequency used makes it tend to interact with water molecules, and heats them up, changing radio energy into heat energy. And that's what heats the food. (note that foods with significant water content heat best)
The microwave is tuned just like an antenna is tuned, to maximize the use of energy. Energy the magnetron takes from electricity has to go somewhere. Energy sent into the box that isn't absorbed and converted to heat is reflected back to the transmitter. This is aka a "standing wave". The "Standing Wave Ratio" tells how efficient the energy transfer is.
A high SWR means a large percentage of the input energy is being reflected, and back to the transmitter where it must be used and so is converted into heat. Transmitters expect some of this because the conversion isn't perfect to begin with, but they're not designed to handle a LOT of additional energy to dump, and will overheat. Very high frequencies like magnetrons use are especially inefficient to start with, and so they're usually designed to cool heavily, with fans and fins. The heat you feel coming out the back of the microwave is NOT heat from the food, it's the waste heat off the magnetron. Adding too much to that waste heat can overheat and damage the magnetron, sometimes very quickly.
So, if you put a substantial chunk of metal into a tuned cavity like a microwave oven, it will interfere with the transfer of energy and cause a higher SWR, which can damage the magnetron. Running a microwave without anything in it is not recommended for the above reason, but adding metal into the mix makes matters worse. Placing nothing in the cavity besides a substantial piece of metal is about as destructive as you can be. The denser the metal, the bigger the effect.
I work for the Department of Redundancy Department.
Recordable discs use gold or silver with negligable oxidation of the reflector. You might get some level of degradation of the dye and call that "oxidation" but we're talking about the reflector, right?
Manufactured discs use aluminum which does oxidize somewhat. In extreme environments with lots and lots of humidity you can get the aluminum to oxidize but only a very few people have ever actually seen it. Mostly this is a myth started by the folks proclaming "DVD rot" which has only occurred in some really odd circumstances.
The problem with shredded discs being put back together is that it will take the drive about 1/4th of a turn to regain tracking after a break. You are NOT going to be able to align the spiral across a break - wraps of the spiral on a DVD are around 1000 nanometers apart. They are a whopping 1400 nanometers apart on a CD so that might be as much as 40% easier.
Since visible light has a wavelength around 500 nanometers, we are talking about features that cannot be resolved by magnification. You might, and I say just barely might, be able to do this with an electron microscope and some sort of micro-manipulator. Maybe.
Having a piece of a sector doesn't do you any good really. The data isn't encoded as bytes on the disc and there is physical scrambling of the bytes to spread them out. For example, to read one sector on a CD you have to read three. On a DVD it is worse - you have to read 16 of them.