Dangerous Science….

josh | Posted 2009.02.25 at 4:02 pm | Perma

So I’ve recently come across this photo of a bank of three capacitors.

capacitor bank (hackerfriendly/Rob Flickenger's flickr)

Now keep in mind that when I say capacitors, I am not referencing the ones you come across in your average electronics lab. I’m not talking about the semi-dangerous ones (read: fun) found in disposable cameras either. These caps are listed as 300 uF @ 10 kV. If I have done my math correctly, then that comes out to approximately 15,000 Joules. Let’s say that again… Fifteen. Thousand. Joules.
Let’s review some basic science. One joule is approximately the energy required to lift a small apple straight up one meter. I asked the following question to a good friend out at UC Santa Barbara who is working towards his MS/PhD in Electrical Engineering: “What can 15,000 Joules do?”. His response was… “[Mess some things] up”. (Expletive Deleted)

That bank of caps is actually part of a coin shrinking operation at hackerbot labs that Bre Pettis posted about on his blog a while back. NOTE: It’s kind of hard to tell who actually put it all together as it took place at hackerbot, the video was shot by a guy from the hazard factory and the photos are from hackerfriendly. If someone wants to claim ownership or straighten things out, feel free.

The gist of quarter shrinking is this: The current from the capacitors is quickly discharged through a single layer work coil. Inside this coil you place a coin. After the capacitors have fired, you will find two things: A work coil that has exploded, and a (hopefully) shrunken coin. The process is called electromagnetic forming and works by subjecting your coin to incredibly strong magnetic fields.

Remember that there is a lot of power going through this contraption. If you do try it at your own hackerspace or even at home, please take as many safety precautions as humanly possible. The remains of the work coil have been known to shatter 1/2 inch Lexan polycarbonate. Like the title says, this is dangerous science and if you might very likely die if you are careless.

To close, my rule of thumb regarding these things is as follows: “If one person says it’s probably a bad idea, it means you should most definitely do it. If two people say it’s a bad idea, maybe you shouldn’t.”


Picture of capacitor bank by hackerfriendly/Rob Flickenger; video by hazardfactor/Rusty.