The first project uses flash units from disposable cameras to produce a disorienting series of flashes to confuse the zombies. The second project uses sound and movement to attract the zombies’ attention. Build these projects and affix them to key locations in your base so you can direct zombies away from you.
Figure 9-1: Smile please!
PROJECT 15: ARDUINO FLASH DISTRACTOR
This flash distractor combines an Arduino and old disposable cameras to produce a timed series of flashes that will confound your brain-hungry foes. Proprietors of old-fashioned photo developer stores are often happy for you to take armfuls of used disposable film cameras off their hands. This is especially true if the proprietors are the animated deceased. They might appear to grumble at you, but I assure you, whatever groaning noises they make are entirely coincidental.
Figure 9-2 shows the completed zombie flash distractor with three salvaged single-use flash cameras, modified to allow the flashes to be triggered by an Arduino. The three cameras are taped together as a block with all the flashes pointing outward.
Figure 9-2: The completed zombie flash distractor
The three flash modules are arranged so that each one points at a right angle to every other, giving 270 degrees of coverage. You will need a separate Arduino for this project as you will not want to position this right next to your control center.
WARNING
If you have a pacemaker or heart problems, or if flashing lights give you seizures, do not build this project.
WARNING: HIGH VOLTAGES AND BRIGHT FLASHES
Flashguns in disposable cameras operate at up to 400V DC. If you want to avoid an unpleasant shock, exercise extreme caution when taking the cameras apart and handling the flash modules. Many parts of the module will be at high voltage and can remain so for hours or even days. Before using the modules, make sure to follow the instructions in “Step 3: Make the Camera Safe!” on page 163 to safely discharge the capacitor.
WHAT YOU WILL NEED
To make this project, you will need the following parts:
ITEMS
NOTES
SOURCE
Arduino Uno R3
Adafruit, Fry’s (7224833), Sparkfun
4-channel relay shield
eBay, http://www.sainsmart.com/
3 used disposable flash cameras
Photo store
PP3 type 9V battery, or larger 9V or 12V battery pack
Hardware store
DC power jack to 9V battery clip adapter
Adafruit (80), eBay
Three 6-inch (15 cm) lengths of bell wire or other double-core wire
Hardware store, scavenge
Auto parts store
For discharging the camera’s flash capacitor
Mouser (293-100-RC)
There are few uses for spent disposable cameras and a store’s only alternative is to pay for someone to take them away, so if you ask store owners nicely, they may give you a stack for free.
Along with a perfectly fine flash module, each camera will generally have an almost unused AA or AAA battery. Try to get a set of cameras that are similar to each other, ideally cameras of the same make. (In the bag of cameras I took away, the most common brand was Fuji, so I based the project on that design. However, the instructions should be sufficiently general to work with any disposable camera.) Also, find cameras that have a switch that turns the flash on for multiple photos, not the sort that make you press the flash button between each shot. For example, look at the camera at the front of Figure 9-2. It has a kind of lever that keeps the flash turned on (bottom center of the figure).
The relay shield was bought on eBay, and when you attach it to the Arduino, it connects a relay to Arduino pins 4, 5, 6, and 7. If you end up with a slightly different relay shield, just check which digital Arduino pins it uses and make the necessary changes in the Arduino sketch (see “Software” on page 166).
The 100 Ω resistor is used to discharge the large, high-voltage capacitor used in the flash module to avoid the risk of electric shocks. It plays no other part in the build.
CONSTRUCTION
Figure 9-3 shows the wiring involved in this project.
Figure 9-3: The flash distractor, spread out
Each of the disposable cameras has a short length of double-core wire leaving one side of its case. These wires connect to the switch contact inside the camera that is used to trigger the flash. I’ll describe how to create this setup for one camera in construction Steps 2 to 5, and you’ll need to repeat those steps for all three cameras.
Each pair of leads connects to one pair of relay contacts on the shield so that the Arduino can trigger each flash independently.
Each camera also has its own AA or AAA battery that powers the flash, while the Arduino and relay shield are powered from a 9V battery connected to the DC barrel jack of the Arduino. This makes the project completely portable, so you can place it wherever needed to create a distraction that lets you escape.
STEP 1: SORT THE CAMERAS
First, sort your bag of cameras by type. To make this project simpler to build, try to pick out three identical cameras. The modules I used were all Fujifilm, though the branding on the cardboard covers differed.
WARNING
Do not try out the Flash of the camera at this stage! It will charge the camera’s capacitor, and you’ll get shocked later when you lever the camera body apart with your fingers. seriously, this really hurts!
STEP 2: REMOVE THE TOP CASING FROM A CAMERA
Used cameras may have already been partly disassembled when the photo processor removed the 35mm film canister. The processors do this quickly rather than tidily, so there’ll probably be cardboard and bits of plastic hanging off. Figure 9-4 shows the steps involved in taking a camera case apart.
Figure 9-4: Disassembling a camera
You are at risk of shock during this step, so take care not to touch the circuit board or any contacts or wires within the camera.
First, remove the cardboard from the camera body (Figure 9-4a). Next, use a flathead screwdriver with a plastic handle (to provide insulation from shock) to lever apart the plastic catches holding the two halves of the camera body together. Remove the front half of the camera case, exposing the PCB and lens (Figure 9-4b). Now remove the lens assembly. Break it off if you have to; it’s not needed anymore. This will expose the two contacts shown circled in Figure 9-4c, which fire the flash when they are touched together.