You will need:
A working disposable camera flash unit, and the knowledge of how to use one safely
An Altoids tin
Soldering iron and solder
Wire (preferably stranded and solid core, but you could get away with either)
1 or 2 small electronics switches
Digital camera capable of taking long-exposure pictures, preferably with a remote
...and for the photos:
Thick card (I use cereal box card)
Something to take photos of (I use a .177 air pistol and sheets of ice or plastic cups and a Fireball gun- get creative)
You may also want:
Fan (for reducing flux smoke inhaled)
Small single AA battery holder
Two friends to help you take photos in darkness
Step 1: Remove Flash Circuit
To open the camera, it may have screws holding the case together which you will need to remove, but most cameras just have plastic locking tabs holding the case on. Break these off, but avoid sticking a metal screwdriver into the case as shorting the wrong parts of the circuit board can wreck it. Once you have the flash unit out avoid touching the capacitor wires or exposed metal parts of the board until you have discharged the capacitor by shorting out the two wires with a metal object. I handle the board by the battery contacts (safe), the casing of the capacitor and the plastic front of the flash bulb.
Step 2: Identify Connections
Battery holder- likely to be two sprung metal tabs that went in the battery compartment.
Charge switch- likely to be two brass contacts separated by a small gap on the front of the board. When the camera was assembled these went under the flash button.
Shutter contacts- likely to be two thin metal contacts with a ~1mm air gap between them. If you click them together with the flash charged, it should fire the flash bulb (it's worth doing that now to chech that the circuit still works). These are at 300V so don't touch with your fingers! Use a pair of tweezers or scissors to do it with.
To test the flash circuit, squeeze an AA battery between the terminals, and touch something metal to the charge button contacts- you should hear a rising whistling noise. Wait about five to ten seconds, and remove the battery. Click the flash contacts sharply together and the flash bulb should fire.
Step 3: Lay It Out
a) find a smaller flash
b) find a bigger tin
c) get creative with the flash circuit board (not recommended)
Determine from the layout where your switch or switches will go, where the trigger wires will exit the tin, and where to situate the battery.
Cut wires long enough to connect:
The -ve terminal of the battery to the -ve battery terminal on the board
The +ve terminal of the battery to the switch contacts
The switch contacts to the +ve battery terminal on the board
The "charge" LED to the edge of the tin if you include it
Step 4: Prep Your Tin
Once you have decided where the switch or switches are going, grab your favourite method of making holes in sheet metal and get going. I made two switch holes before realising that I was only using one switch, so routed the trigger wires through that hole instead. The charge LED is completely optional, but we all know that all good hacks have an LED in them somewhere...
Step 5: Wire It Up (again)
Solder the appropriate wires depending on your circuit, whether you are using one or two switches and whether you include the LED. It's unwieldy to explain in writing so I'll just give the circuit diagrams- however you wire it up, the circuit board should have wires soldered to the battery terminals, charge switch terminals, shutter switch terminals and optionally the "ready" LED wire. Once you have the wires soldered on, tape the power wires to the battery (or put the battery in the holder), push the switch through the hole in the tin, screw the nuts on to secure it and settle the circuit into its new home.
Once you have the trigger wires at a comfortable length, add a strain relief on the inside. I prefer to tightly put a zip tie around the trigger wires, but you can just tie a knot in them at this point.
Step 6: Fire It Up
Step 7: One More Hole to Make
Put the circuit back into the tin to check that the bulb sits underneath the hole you've just cut, and tape or otherwise secure the circuit inside the tin if it moves around.
Step 8: Make Your Contact Switch
Cut two pieces of card, between 10cmx15cm and 15cmx25cm. Line one side of each with foil with the shiny side outwards to make the contacts. I found it useful to put a spacer underneath the foil before taping the edges to make it bulge outwards slightly in the middle. Attach a spacer a couple of cm thick near the top of one of the pieces of card on the foil side, and tape the other piece of card to the spacers with the foil side inwards, so the tape forms a swinging "hinge". When stood upright, a light tap to the back of the swinging piece of card should make the foil contacts touch together.
Step 9: Get Creative!
- Rig up the switch in a vertical position as in the last photo with a sturdy support behind it- a thick hardback book you don't mind damaging, a strong cardboard box with something in it to weight it down, use your imagination.
- You may want to reinforce the back surface of the switch contact that's taking the impact- for the ice photos the .177 pistol I was shooting with would have punched straight through the card switch so I taped a wad of double-thickness corrugated cardboard to it. I don't recommend shooting this with anything more powerful than air weapons, but if you can get a picture of an M107 round going through a watermelon or something I'd love to see it.
- Stand something that will look cool in front of the switch. The spacing determines the timing of the flash- put it very close to the switch to catch it instantly after being hit, further away to allow it longer to come apart before the flash fires. Experiment.
- Set up a camera on a tripod aimed at the target. Ideally, a camera with timed remote shutter would be helpful, or you can draft in assistants.
- Charge the Minty Strobe, making sure the switch contacts aren't touching
- Turn out the lights, open the camera shutter, fire/throw/propel objects at your target and hope the flash goes off. Wait for the camera shutter to close, turn the lights back on, check your photo.
You'll probably need to experiment to find the best aperture and ISO to give a good exposure, unless you're a super-l33t photographer with light meters and such, in which case you probably don't need me telling you what to do.
Step 10: Here's One I Made Earlier