Its really hard (i.e. expensive) to create really convincing lightning, but its easy to get 85% of the way there. What you need is an intense white light that has a very fast attack and decay time.
What do I mean by attack and decay times? I'm talking about how long it takes for the bulb to reach full brilliance once the power is applied, and how long it takes for the bulb to stop glowing once power is removed. Conventional theatre lamps are pretty "slow" in this respect, just look at a parcan chase: once the speed gets up a bit most of the lights are on at the same time, just at varying levels of intensity.
The humble domestic light bulb (GLS) is much better in this respect than any of the 'proper' theatre lamps, but they are not really bright enough, not "white" enough, and phyiscally quite large for their wattage, particularly in the 150/200 watt guises.
However there is a particular type of bulb available called a "photoflood" bulb, they are perfect for this application. They are the same size as a 150W bulb, but are 500W, and they are much "whiter" than the humble GLS. Their downside is that they have a short life, just a couple of hours. But boy, for those couple of hours, these bulbs are stellar performers.
These lamps were very popular for photo studio lighting before the rise of the low cost xenon studio flash units. This is where to go first to source these lamps; your local photographic warehouse.
So, to make a lightning effect, get a couple of photoflood lamps, bung them in a couple of old flood fixtures that accept ES (screw) lamps, connect to a couple of dimmer channels, and flash away.
Theres a problem here though. These days its really hard to get flood fixtures that take big size GLS style ES lamps. Modern floods use linear halogen tubes. Times have moved on. So, we need to build something for the job, and here is a cheap and cheerful old fashioned flood.
And a couple of words of warning - when I was a lad, my photo books told me these lamps have a habit of exploding. I've never seen it happen, but apparently it can and does, so make sure that an exploding bulb wont compromise show safety. Also, these lamps get hot - very hot. They are fine for effect use, but for prolonged use they can stress a light fixture to failure.
This project uses mains voltages, which are hazardous, and can cause death. Your insurance company may not like you building this project, nor may they like you using one of these in a show. Your theatre may even object to you using DIY effects in their venue. Ensure that you (and your show) have appropriate cover for your activities and liabilities. And heed the warning herein about exploding bulbs and heat buildup.
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What you need is:
The construction of this fixture is obvious, the only warning I must make are about ensuring earth (ground) continuity, and ensuring that the cable can't be pulled out of the unit. I use grommets with integrated cable strain reliefs, and in addition put a couple of tie wraps around the cable in the lampholder fixture. There isn't much space!
I like to leave the earth wire longer than the live and neutral, that way if the cable is pulled and starts to rip out, the earth is the last to let go.
Finally, as noted earlier - these bulbs get hot - this fixture is not suitable for any duty cycle other than flash effects!
Thats all there is to it!
Use a couple of these units, and point them at big white surfaces, like the auditorium ceiling (if not too high) walls, backcloths etc. Auditorium based lightning is particularly effective, it drags the audience into the show, rather than allowing them to be passive observers! Having a couple (or a few?) of these units gives "movement", and this seems to be the key to a convincing lightning experience.
You need a desk equipped with flash buttons or a chaser. Or a show control system, so you can sync up the sound and light effects.
No show control system - you can use the Cubase demo sequencer that comes with your Soundblaster Live! card to deliver the audio effect and MIDI triggers, and using a MIDI interface to control a few channels of dimmers.
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