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Theatrical Effects: Replicating a Pyrotechnic Effect Without Any Pyro

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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.
 
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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.
  1. 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.
  2. 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.
thegeeke1 year ago
Nicely done! As someone who grew up programming intelligent lights for theater, I have 2 more suggestions about how this could be done.

1. Position an elipsoidal, ParNel, or Scoop behind the actor (or just to the side) so that they are pointing into the audience. Preferably 2-20 fixtures. Use plenty of haze (preferably haze and not fog). At the correct time, flash your lights behind the actors so that it gives an intense effect towards the audience making them feel like the broomstick was pointed at them. It get's really fun if you can use gels and do different colors.

2. Use as many intelligent lights as possible strobing different colors, positions, and if you have any decent gobos for the effect use gobos as well on the person the broomstick is pointed at. If you do it right, the lights should be only on the person the broomstick is pointed at, and the audience will be so dazled by the sudden lighting that they will not even notice that the broomstick didn't have any effects on it. It takes about an hour to program this sequence and it only lasts for a few seconds, so don't think this is the easy effect. ;)

There are other ways of doing it, but these two (aside from pyrotechnics) are my favorites. Your ible is a fantastic option for groups that have extremely limited resources though! :)
Oh, with the static fixtures, don't flash them all at once, do them one or two at a time (depending on how many you have) randomly for a split second each. :)
pjensen (author)  thegeeke1 year ago
I considered most of those, but due to the staging (the actress was up on a 4 foot tall platform at the very back of the stage), it would be almost impossible to get the lights positioned correctly for the effect.

In the space we were using, there were 8 old intelligent washes that we could have used to finish up the effect, but they don't produce very much light... I have done something similar to your #1 suggestion before, and it has worked great, but it just wouldn't work in this situation.

In this same show however, I did use a combination of an ellipsoid with a lightning gobo and the intelligents on the scrim to produce a stunning lightning through clouds effect. With everything flying behind the scrim (Remember, this is the Wizard of Oz, specifically the tornado scene...), the effect was perfect.
Yes, I understand that the ideas I stated would not work in every situation, but I didn't see them in your effects list at the beginning, and since the idea for this instructable is to help people with their theatrical effects and based off of your picture I would say I got started in theatrical effects (lighting, sound, etc.) just about the time you were born, I just thought I would throw that in. ;) (Like I said, good job! As a matter of fact, I probably wouldn't have even thought about doing it the way you did.)
pjensen (author)  thegeeke1 year ago
I agree, I probably should have included them, but I kinda forgot about it... Oops...

And second, Thanks!

Who do you do lighting for?
I own a media production company, I mainly do freelance sound, but I still dabble in lighting from time to time. I started in sound for my church when I was 7, and I started doing intelligent lighting for community theater when I was 8 or 9. Most of my real "training" is in intelligent lighting, even though I consider myself more of an audio guy than lighting. I enjoy both though! (And since my first "real" job was at a climbing wall, I also train people on how to work on lighting and rigging.) :)
bonanno.mark5 months ago
Yeah, I saw the trigger going behind the reflector. I did as you did in the instructable and wrapped a stripped wire around the bulb. I experimented with moving the wire to see if I got a better firing rate. You are right that it needs to be at one end (I believe nearest the negative lead). I think though that you have a good point in saying that the trigger lead needs to have very low resistance. I handed over a broom today (they are on the stage for the first time today). I think I will try re-soldering the trigger lead on one of the other attempts and see if the firing rate improves.

Thanks for the help. I will keep you updated!
bonanno.mark5 months ago

pjenson - I am trying to re-create this (for the wife's WoO). I am having the devil of a time getting the flash to fire as often as it does when it is on the camera. I checked my voltage across the bulb leads and am getting 300v. I can get the bulb to fire but sometimes it takes 20 to 30 seconds before it will trigger. When I put a VOM on the trigger to ground leads I see that I don't have 300v. Any suggestions on what I am doing wrong?

pjensen (author)  bonanno.mark5 months ago

Hmm, the trigger lead will only reach 300 volts when the flash is firing, which is often times too short for a multimeter to register. Does the indicator light turn on right before you can fire it? Or does it come on almost immediately after firing?

You can also measure the battery voltage. If the battery is low, it will take longer to charge. You want a battery with a voltage above 1.4 volts for ideal use. One other test that you can do is measure the voltage across the capacitor after you fire the flash. You should see the voltage slowly rise back up to 300 volts. Once the capacitor reaches around 270 volts, you should be able to trigger the flash. The time it takes for the capacitor to reach 300 volts is the limiting factor in most cases. If you still are having issues, you might have a bad switch.

Also, the brand of camera that you use can affect the charge rate. I used a Kodak Powerflash, but if you have a different camera, it might be slower.

pjenson - first off, thanks for the reply. I appreciate it. So, to answer your questions....

I have a "Max Hold" on my VOM and it USUALLY is fast enough to catch the trigger voltage. When the circuit fires, it USUALLY registers above 300v. When it isn't firing I can actually watch the voltage climb up to the required 300 as I cross the "shutter/fire" leads multiple times.

I tried several batteries (including some Lithium). I never got the same rate of firing that I was able to get off the camera. When the circuit is untouched (still on the camera) I am able to fire every 4 or 5 seconds. Once I removed components from the board.... firing became erratic. All the batteries had a voltage greater than 1.5 (the Lithiums where closer to 1.7).

I measured the voltage at the bulb, that SHOULD have been the same as the capacitor, right? It read 300v.

I have to admit, I thought the problem was first one switch and then another. Finally I just started crossing the leads leading to the switch. At first it seemed to work - then I was back to the erratic behavior.

I will say that I bought several (cheap) cameras and all of them had the issue. As soon as I moved the bulb off of the board, firing would become erratic. Now, that seems to point to my soldering (which I will say is not the best). So I used alligator jumper leads. Same issue.

In the end I gave up and kept all the components on the board (there was a LOT of 4 letter words expelled before I did this). I have soldered the "charge" leads down and actually soldered the leads for the switch directly to the copper tangs that are on the board. At the moment everything is working and I am able to get a good firing rate of every 5 seconds. Of course, this means that I have the entire unit to put at the end of the broom. That is a job for the morning. I am including some pictures of the Frankenstein's Monster that I created. I will post what it looks like in the broom tomorrow.

Thanks!
IMG_20140215_233728.jpgIMG_20140215_233714.jpg
pjensen (author)  bonanno.mark5 months ago

Aha! I think I found your problem. When you took the bulb off the board, did you move the reflector with it? When the flash fires, the whole reflector gets brought up to 300 volts. There should be a little copper lead which goes in between the board and the reflector, and that needs to be securely attached and have low resistance to the reflector. Alternatively, you can just do what I did, and form it into a loop that fits around the bulb, and ditch the reflector entirely. The catch with that is the loop needs to go around the correct side of the bulb or the flash might not fire.

nbonanno5 months ago

This looks great and just the kind of thing I need to do in a church production of Wizard of Oz. I assume there was a button the Witch pushed to make the flash...where was it hidden?

pjensen (author)  nbonanno5 months ago

Thanks! If you notice the main image, you can see how her hand is positioned right at the base of the broom's bristles. That is where the button is hidden. The bristles had about two inches of extra length above the coil on the broom, so I could tuck the button the coil, and the board underneath the coil. You can see this clearer if you go to step 14, and look at the annotations on the image.

nbonanno pjensen5 months ago

How embarrassing. I had found this front page with a search and didn't realize there were actually steps I could follow! And how nice of you to take the time to show the rest of us how to do this!

pjensen (author)  nbonanno5 months ago

Hah! No problem! We all have that one moment of visiting a new website and completely failing at it! Welcome to Instructables!

This is really neat. Do you have any video of it working?
pjensen (author)  SelkeyMoonbeam1 year ago
I do not, but I can get a video of my demo board working. Unfortunately, before I could remove the actual board from the broomstick, the props people had taken it, and I have no clue where it has gone.

I will work on that right now, and it should be ready in a couple of hours.
Thanks, I am excited to see!
pjensen (author)  SelkeyMoonbeam1 year ago
Done!
Thanks, nice video!
pjensen (author)  pjensen1 year ago
Well, I tried. Very hard. The problem is the device produces too much light for my camera to capture. When I try to do a walk-through of the device, and I fire the device, all you can see is a completely white screen. If I decrease the exposure, you can't the board, all you can see is the flash.

I can still post the video, if you want to see the white screen of the flash.
CarpePM1 year ago
Well done. Very creative.
pjensen (author)  CarpePM1 year ago
Thanks!