Theatrical Effects: Replicating a Pyrotechnic Effect Without Any Pyro

No pyro? What fun is there in that? Well, unfortunately, for Woodbury Community Theatre's prodution of the Wizard of Oz, the high school would not let us use pyro in the theatre (And anyways, hiring a licensed pyrotechnician for the shows would cost over 5 grand, plus the cost of filling the necessary paperwork.). Oh, well. I guess we will have to figure out how to make all of the nice effects without any pyro...

The effect that I am going to be replicating is a firecracker. The effect needed to produce a large quantity of light in a very brief period of time, mimicking the flash from a firecracker, or an airburst, or a small amount of flash paper. The flash that is required is larger than usual, because theatrical lighting is much brighter than usual, around the house lighting.

Here is a video of the demo board that I created for this Instructable. I apologize for my camera's inability to adapt to the rapid flash from the device.

Step 1: Different Methods of Creating This Effect

I thought of several methods to solve this issue. Each effect has its own set of pro's and cons, that I will detail below.

Effect	Description	Pros	Cons	Safety
Pyrotechnics	We hire a licensed pyrotechnician to come in and rig the witches broomstick with a pyrotechnic flash.	Large flash and a bang, syncronized perfectly, a small amount of smoke Flash eminates from broomstick	Extremely Expensive Only one flash per "loading" of the prop	Moderately Safe
Focused Incandescent Fixture	We position one of our ellipsoid fixtures and position it to illuminate the end of the broomstick, coupled with theatrical fog to simulate an explosion.	Bright flash with smoke Zero-cost Can syncronize with sound effect to create bang	Impossible to point, and repeat for each flash (The actors would not be able to hit the exact same spot, every single time) Incandescent bulb heat up time doesn't create a quick flash (Think cheesy theatrical/movie lightning)	Extremely Safe
External Strobe Light	We rent, and mount a large strobe light on one of the flies, and use it to illuminate the entire area.	Bright Flash Low cost (We have a company nearby who rents to DJ's for extremely low prices) Floods the entire area	Fairly hard to syncronize to bang (internal variances in strobe light can cause the bang to happen before or after the flash, ruining the effect.) Flash does not eminate from broomstick	Extremely Safe
LED Strobe Light	We build a small LED-based strobe light, which can be mounted in the tail of the broomstick.	Fairly low cost An excuse to use high power LEDs Lower voltages keep it safe Flash eminates from broomstick	We would need at least 20 LEDs to create a large enough flash, so disguising the flash unit would be hard Fairly hard to syncronize to bang	Extremely Safe
Disposable Camera Flash Strobe	We disassemble a disposable camera to steal the flash unit, mounting it in the tail of the broomstick.	Zero-cost (All parts were found in my basement) Bright flash An excuse to tear apart a disposable camera and use the high voltage stuff inside (Haven't you ever wondered what was inside one of those things?) Easily disguisable (Flash tube is small, and battery pack can be hidden in the tail) Multiple flashes can be achieved without having to reload the prop.	Fairly hard to syncronize to bang. Extremely high voltages can injure actors if misused or misbuilt	Moderately Safe

As such, I decided to go with the Disposable Camera Flash. To combat the cons of this method, I came up with the following solutions.

Synchronization: To synchronize the flash to a sound effect, we created a two part effect. The first part was a "charge up" sound effect. This lasted about 3 seconds, and was promptly followed by a large bang, with some thunder mixed in. The plan was to fire the sound effect when the witch pointed her broom, and then she would fire the flash right before the bang happened, so they occur simultaneously to the audience.
Insulation, insulation, insulation. To protect the actors and the techies in charge of preparing the broomstick, I wrapped the PCB for the flash in a layer of Gaff tape, which provided a thick insulating layer, but still provided access to the charge button and battery holder. I also double insulated the connections at the flash tube, with a double layer of shrink tubing, and multiple layers of clear packing tape around the tube. This was a very important step, as the ends of the tube carry 300 volts constantly when the flash is fully charged.

Step 2: Disclaimers and Safety

Yes, I am going to have to run through this, but as this project has the potential to cause bodily harm if misused, I feel obligated to state the following.

I AM NOT RESPONSIBLE IF YOU DO NOT FOLLOW THE INSTRUCTIONS, AND GET BLOWN ON YOUR REAR END. THIS PROJECT INVOLVES EXCESSIVELY LARGE VOLTAGES, AND SHOULD BE HANDLED RESPONSIBLY.

This project is fairly dangerous, and can injure people. Please, be responsible, and be careful. Use common sense.

ALWAYS TREAT THE DEVICE LIKE IT IS LOADED.
ALWAYS TAKE THE BATTERY OUT BEFORE WORKING ON THE DEVICE.
But just because the battery is out does not mean the device is safe to touch. The main capacitor can remain charged for days after the device has been charged up. When I came in one day for a show, I checked the device to make sure that it worked. Before touching it, I made sure to trigger it. And a full 22 hours after being charged, the capacitor had enough power to fire the flash one more time. THIS CAPACITOR IS DANGEROUS. USE CAUTION AROUND IT. Make sure to discharge the capacitor by firing the flash unit (whether it flashes or not) at least 3 times, and then discharge the capacitor by touching the leads with a screwdriver that has an INSULATED handle. This will make sure the board is safe to use.
The flash tube has a constant 300 volts applied to the ends of the tube whenever the capacitor is charged. If you touch the ends, you will get a shock. And the tube is glass, so be careful with it.
If you are reading this step, good job. You can skip step 3, and move on to step 4.
This Instructable assumes that you are fairly well versed in electronics, and is NOT RECOMMENDED for beginners. I REPEAT: If you are looking for a beginner project, this is not the project you are looking for.

Camera selection: I used a Kodak PowerFlash Disposable Camera. This camera has an Auto-Recharge function, which causes the flash to recharge once it is discharged. Some cameras do not have this feature, and need to be recharged after firing the flash. I would recommend a camera with the auto-recharge feature.

Step 3: Go Back and Read the Disclaimer Again...

If you are looking at this step, then you haven't read the disclaimer. I told you to skip step three, and since you obviously haven't, you should go back and read them. To lazy to do it? Here they are again:

Yes, I am going to have to run through this, but as this project has the potential to cause bodily harm if misused, I feel obligated to state the following.

I AM NOT RESPONSIBLE IF YOU DO NOT FOLLOW THE INSTRUCTIONS, AND GET BLOWN ON YOUR REAR END. THIS PROJECT INVOLVES EXCESSIVELY LARGE VOLTAGES, AND SHOULD BE HANDLED RESPONSIBLY.

This project is fairly dangerous, and can injure people. Please, be responsible, and be careful. Use common sense.
ALWAYS TREAT THE DEVICE LIKE IT IS LOADED.
ALWAYS TAKE THE BATTERY OUT BEFORE WORKING ON THE DEVICE.
But just because the battery is out does not mean the device is safe to touch. The main capacitor can remain charged for days after the device has been charged up. When I came in one day for a show, I checked the device to make sure that it worked. Before touching it, I made sure to trigger it. And a full 22 hours after being charged, the capacitor had enough power to fire the flash one more time. THIS CAPACITOR IS DANGEROUS. USE CAUTION AROUND IT. Make sure to discharge the capacitor by firing the flash unit (whether it flashes or not) at least 3 times, and then discharge the capacitor by touching the leads with a screwdriver that has an INSULATED handle. This will make sure the board is safe to use.
The flash tube has a constant 300 volts applied to the ends of the tube whenever the capacitor is charged. If you touch the ends, you will get a shock. And the tube is glass, so be careful with it.
If you are reading this step, good job. You can skip step 3, and move on to step 4. (See, there is the instruction...)
This Instructable assumes that you are fairly well versed in electronics, and is NOT RECOMMENDED for beginners. I REPEAT: If you are looking for a beginner project, this is not the project you are looking for.

I told you so. You should always read the disclaimers...

Step 4: Disassembly: Step 1

Now, it is time for the fun stuff! The first step to any good disassembly job is to crack the case. In the case of the camera that I am using, there were four tabs around the edge of the case. Carefully pry apart the case, making sure to avoid the board to prevent shocks.

Step 5: Disassembly: Step 2

Now that the covers are off, it is critical that we discharge the board. Remove the battery, and find the trigger contacts on the board. Short the trigger contacts, and hopefully the flash will go off. Whether or not it does, you should still short the capacitor leads afterwards.

Step 6: Disassembly: Step 3

Now that the board is discharged, we can clear out all of the unnecessary components of the camera, including the shutter trigger button, film reel, film, shutter, shutter spring, film winding mechanism, lens, and viewfinder.

But first, take a look at the ingenuity of the trigger for the flash. To ensure that the flash occurs when the shutter is open, the manufacturers of the camera made the shutter the trigger for the flash. When the shutter opens, it contacts a rail at the bottom, completing the circuit, and triggering the flash.

Step 7: Disassembly: Step 4

Now, we can ditch the camera's enclosure. My board was attached with a single clip, circled in the photo. From there, the board simply pulled off of the enclosure.

Step 8: Electronics: Preview

Since we have freed the board from the case, we can now start on the electronics.

Several things to notice:

The two trigger bars: We will be modifying those to act as the trigger for the flash.
The charge button: We can either leave the charge button, or add a second switch somewhere else, to allow the flash to be charged remotely. For our production, we had enough time to charge up the unit before the Witch's entrance to prevent us from needing to remote the charge button.
The battery holder: For our production, we used a rubber band to hold the battery in place, but it tended to rattle loose. I would recommend adding a single AA holder instead of the current holder.
The Flash Tube: The business end of the flash, it consists of three contacts. There is a terminal on each side of the flash tube, and then a single contact near the center of the tube to draw the arc across. Once the tube is charged, applying 300 volts to the center contact will draw the arc across, causing the flash.

Step 9: Electronics: Step 1

Now, it is time to finish up the last disassembly step. We need to clean up the board, freeing the flash tube, and getting rid of the trigger bars. Dig up your solder sucker, soldering iron and let's go!

The pictures correspond to the steps below.

Gather your tools. Then take off:
One of the trigger bars.
The other trigger bar.
The flash tube.
The flash tube supports
The flash reflector. This pushed off easily once the flash tube was removed.

Step 10: Electronics: Step 2

The photos correspond to numbers again.

Let's work on the flash tube.
First, solder on two leads, of the length that you desire. For this project, I am only going to be moving things out about 4 inches, but I have gotten the flash to go off when the bulb is 3 feet out.
Then, cut enough heat shrink to cover the leads and a good amount of the wire.
Shrink the shrink tubing.
Now, we need to create the trigger lead. Cut another lead, preferably out of a different colored wire, and strip the end down enough to allow you to make a complete ring around the flash tube.
Solder the trigger lead into a loop around the flash bulb.
Move the ring to one end, and bend the ring to follow the other lead. This is just one reason why the shrink tubing is important...
Cover the entire assembly with either clear shrink tubing, or (less preferred) use clear packing tape. I didn't have clear shrink tubing of the correct gauge, so I had to settle with clear packing tape.
Solder the entire assembly to the pads on the PCB. Make sure to attach the leads to the correct pads. If you do this incorrectly, you could have a very dangerous situation.

Step 11: Electronics: Step 3

The final step in electronics is to attach the trigger switch. If we didn't have a trigger switch, it would be hard to fire the flash, would it not?

Find a switch. It needs to be Momentary and Normally Open (NO). Other than that, be creative. And, wire on another set of leads.
Solder the leads to the PCB. My board had two pads for one of the trigger bars. Obviously, if you wire them up to those pads, the flash will not work...

This concludes the electronics portion of this Instructable.

Step 12: Test!

We can now pop in a battery, and confirm that the flash unit works.

Carefully insert the battery, and push the charge button WITH A NON CONDUCTING TOOL. I am not sure how much voltage runs through the charge button, but to be safe, push it with a tool... Wait a second, and then release the switch. Hopefully, you should be able to hear the whine of the flash charging up. If not, don't fret, it might be just inaudible.

Then, the moment of truth. Press the trigger switch, and the flash should fire! If it doesn't check your connections, and make sure everything is correct. Make sure the battery is in the correct direction.

Wait about 3 seconds, and then push the trigger again. The flash should fire again.

Pull the battery, and fire the flash twice. This should almost fully discharge the capacitor, and then discharge it the rest of the way, using a tool with a non-conducting handle. THIS IS CRITICAL. Notice the second picture. Even though the battery has been pulled, the capacitor still has enough power to light the neon bulb, and can still fire the flash again.

Step 13: Insulate

Wrap the entire package in your choice of insulating tape (I used black Gaff tape). I left the battery easily accessible, but you can cover it up if you like. Make sure to do this properly, it looks nice if you take your time, and is much safer. You could also use a project box.

Step 14: Disguise in the Prop

It's now time to disguise the flash in your prop. For the witch's broomstick, I placed the battery pack in the tail of the broomstick, and left the flash dangling out the back. The trigger switch went in the top of the tail, where the witch could push it easily. When the pack was tucked inside the tail, the distance from the broomstick to the audience keeps everything practically invisible unless you know that the unit is there.

Be creative! Expose the wiring if it works, hide the wire in pipe, hide it in a plant, the possibilities are endless!

Step 15: Use

Right before the actor's entrance, you need to charge up the prop. Insert the battery, and push the charge button. This should prime the prop, so the flash will fire.
Once the actor needs to fire the unit, they should be able to just push the trigger switch, and the flash will fire. They can then wait 3 seconds, and the flash should have recharged, and can be fired again.
Once the actor gets offstage, pull the battery, and fire the prop until it will not fire anymore. It should now be safe(r) to handle.

Step 16: Ideas for Improvement

This concludes this project, but, I will leave you with the following:

As this is a theatrical prop, there are many ways to improve the effect.

Better battery holder: For more permanent installations, I recommend replacing the battery holder with one that has a switch.
Remote the charge button: To allow the actor to charge up the flash themselves, I would recommend attaching another switch that replaces the button on the PCB. This will simplify charging the circuit, and provides a backup.
Reorient the main capacitor: Every night, I had to repair the capacitor, by bending it back into place. If the location of the battery pack is taller, you can take and reorient the main capacitor upright. This reduces the chance that it will get bent. I considered it, but it wouldn't work in our case.
Better Case: Please, if you have the time and the option, install it in a plastic case... Please...
Multiple flashes synced together: By using a Dual pole, single throw (DPST) or a dual pole, dual throw (DPDT) switch, you can synchronize multiple flashes fairly accurately.

Introduction: Theatrical Effects: Replicating a Pyrotechnic Effect Without Any Pyro