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So here's the story: We are three nerds (Isaac, Damon, and Reid).
Upon Damon's return from MIT to our native quaint mountain village of Ashland, Oregon during winter break, he decided that the
BASIC micro-controller he had just procured should be used
in
a
high-speed flash photography lab. This was something Damon and Isaac had considered before, but not very seriously.
Anyway, for this we also needed something moving or changing very fast, so we decided to build a bolt gun.
Of course, bolt guns aren't very fun unless you can
see, in great detail, the object they are hitting explode, so these two projects seemed like a match made in nerd heaven.
With the aforementioned
micro-controller, we simply had no choice but to build a flash timing
mechanism to capture images of hot bolt-on-food action.
The mechanism works something like this: An air compressor is used to build up pressure behind a sprinkler valve. This valve is attached to a long PVC pipe which acts as the barrel of our gun. A button is hit, telling the micro-controller to open the valve, thus releasing the pressure and sending the waiting bolt hurdling forth at around 150 m/sec towards its suculent victim. When the bolt exits the barrel, it dislodges a piece of paper (thanks, Reid for the idea) which is blocking a beam of light. Once the paper is gone the light hits a photo-resistor, thus lowering the voltage output of a voltage divider, and triggering a binary input pin on the micro-controller. At this point the micro-controller counts to a number dictated to it by some DIP switches. We used a delay of 5 ms in most of our pictures. After this delay, the flash is triggered through a high-current relay. We simply set a couple of nice digital cameras (thanks, Damon's mom and Isaac!) to long exposures while the lab was completely dark, so all the cameras captured was the image at the time of the flash. This timing worked out so well in our lab sessions that we could determine where we wanted the bolt to be in relation to the unfortunate edible object in the shot by simply moving the morsel forward or backwards a few inches. The flash we used was a disposable camera that Damon gutted and soldered a relay into. Considering the speed of the bolt when it exited the barrel, the flash performed quite respectably for a disposable. Anyway, that's about all there is to it, so have a look at the pictures. In some of them you can see the piece of cardboard used to block the photo-resistor flying by in the background. All pictures were taken in Damon's garage-lab (thanks, Damon's garage!) Note: even though we're absent minded, we (gasp!) did consider our safety in doing this. We put a slab of old carpet behind the fruit we were shooting, in the path of the bolt. This way the bolt didn't go across the room, bounce off of various objects, and become swiftly lodged into our soft brains. If you try something like this, we highly suggest you block the path of your projectile in a similar manner, wear goggles, and don't sit too close to the end of the barrel, like Isaac did. If you want any of these pictures in a larger format, take a look here We can be contacted at: doombolt@truffula.net. |