Silver (Ag)-  The best conductor. Silver conducts electricity better than gold and costs less. Why, then, is gold used to plate electrical contacts in high-quality switches and in computers? (Silver tarnishes when it combines with impurities in the air and loses its conductivity.)

Nitrogen (N2) (liquid) - Used for making fog.  This liquid, stored at about -200 degrees Celsius, is sprayed over hot water to make the fog.

Phosphor (P) - coats the inside of fluorescent tubes and neon tubes.

Neon (Ne) - noble gas used in neon tubing to give a red-orange glow when energized.

Argon (Ar)- noble gas used in neon tubing to give off a bluish glow when energized.  Also, used in laser tubes to emit a greenish beam.

Krypton (Kr) - noble gas used in laser tubes to emit a red beam.

Halogen - gas made from the salts (group VII in the periodic table: Flourine (F), Chlorine (Cl), Bromine (Br), Iodine (I), Astadine (At)) inside of T-H lamps.  Helps replenish the Tungsten.

Tungsten (W)- metal used to make filaments in most lamps.

Brass - compound made of Copper (Cu) and Zinc (Zn) used in terminals on many different connectors.

Dry ice - solid Carbon Dioxide (CO2) stored at around -75 degrees Celcius.  Used to make fog.  Typically the ice is held in a basket of sorts and the water is sprayed over the ice.

Mercury (Hg) – one drop is used in fluorescents.

Refraction – bending of light waves through one medium to another.

Reflection – bouncing of light waves off a surface.  Angle of incidence = angle of reflection.

Absorption – when a material does not allow a light wave to continue on its path.  The wave is absorbed and transfered into heat.

Instrument stuff

The output of a “ballast” is typically low amperage high voltage.

Articles 310, 400.5 and 520 in the National Electrical Code should be read.

Be familiar with NEMA codes for connectors.

Dimmer racks are hooked up in the order Gound, Neutral, Hot, Hot, Hot.  Interlocking connectors must be used

 

 

Beam angle math.

Tan(1/2 of the beam angle) = Radius of lens/focal length

If you know the beam angle, ex: Source 4, 26 degrees:

  1. Divide by 2 = 13 dgrees.
  2. Take the Tangent of 13 = 0.231
  3. The diameter of a Source4 lens is 4", the radius is 2".
  4. 0.231 = 2"/Focal length
  5. 0.231 X Focal length = 2"
  6. Focal length = 2/0.231
  7. Focal length = 8.65"

If you know the Lens diameter and focal length, ex: 6 X 12:

  1. The radius of the lens is the diameter/2 = 3"
  2. Tan(1/2 of beam angle) = 3"/12"
  3. 1/2 of beam angle = Inv Tan (3/12)
  4. 1/2 of beam angle = 14.036
  5. Beam angle = 28.072 degrees

 

Tan(X)=Opp/Adj     This will give the answer in degrees.

Ohm's Law:  E = IR

Power Formula:  W = VA

One DMX universe can control 512 channels.  There are 3 universes of DMX in an Obsession II.

2 wires plus shield are required in a DMX cable.

The shield helps absorb stray RF and protect the signal.

In Commercial Theater, the Production Electrician or Head Electrician is responsible for maintaining the lighting design after opening.

The gate of a Source 4 contains 4 shutters, an iris slot and a gobo slot.

The purpose of cue lights is to signal stagehands when to standby and when to take cues

Name five positions in the electrics/sound department (not designers):
  1. FOH mix, monitor mix, sub-mix
  2. Sound FX op, FX lighting op  
  3. Light Board op
  4. RF technician, Pyrotechnician
  5. Deck electrician, FOH electrician
  6. Moving Light Tech

Arc-lamps require a douser in order to fade out.

Light waves travel approximately 893,000 times faster than sound waves.

Over-current protection – protects a circuit from being over-drawn, over-heating and ultimately starting a fire.

Gig-butt – a condition caused by long hours of sweaty work with no change of clothes.  Chaffing of the buttucks.  Yes, this one would be for E.C.

Sine wave – a graphical representation of alternating current, and/or a pure sound wave.

Free – electrons – electrons that are easily forced from their atomic orbits.

Headroom – room to expand or "having spares."  Comes from the sound term that means the difference between "loud enough" and "distortion."

3-phase ‘Y’ – 120v/208v.  3 hots, neutral and ground.  Power generally used for most theatrical equipment.

3-phase 'Delta' - Has high leg. 3 hots and ground, sometimes neutral.  Power generally used for motorized equipment.  Not good for dimmer racks.  Should have one leg marked in Orange.

Dichroic glass – incorporates the use of layers that reflect certain light waves but allow others to pass, filtering out the undesired colors of the spectrum.

Chromatic apparition –  the edge of a focussed beam of light where the "white" light appears to be blue/green/brown.  This is where the refraction of the lens has caused some "scattering" of the light waves.

If a 5-pin, 30-amp twistlock connector provides power for a device on the other side of the stage from its location, and the cable must run along the floor you would need to use 10/5 SO.

Acronyms:

  1. USITT - United States Institute of Theater Technology - Attempts to get manufacturers, professional theaters and universities to collaborate. Created DMX512 standard based on RS-485.
  2. NEMA - National Electrical Manufacturers Association - Writes standards for connectors.
  3. USA (Not the country) - United Scenic Artists - Designer's Union
  4. IATSE - International Alliance of Theatrical Stage Employees - Stanghand's union.
  5. NFPA - National Fire Protection Association - Publishes codebooks that are used as basis for electrcal safety laws.
  6. NEC - National Electrical Code - Codes used to make electrical construction laws.
  7. ANSI - American National Standards Institute - Creates standards for bolts and cable ratings among others.
  8. BTR - Big Time Roadie - A stagehand that has reached the point of choosing what the next job is instead of begging for one.
  9. FDA - U.S. Food and Drug Administration - Started by FDR and the alphabet government, they regulate food, drugs, lasers and cell phones.
  10. BATF - Bureau of Alcohol, Tobacco, Firearms and Explosives - aside from the obvious, the ATF regulates pyrotechnics.
The primary colors of light are red, blue and green.  The secondaries are cyan, yellow (or amber) and magenta.  Light from all three primaries or secondaries each with their own source of white light, will create white light onto a white surface.  If two of any primaries, two of any secondaries or one primary and its compliment are used to filter white light, no light will pass.

Tinted glass (such as Devon) filters light using absorption.  Dichroics use reflection.

Color temperature is defined by the "Black Body Theory."  Measured in Kelvin, Tungsten Halogen lamps give off about 3200 degrees.

"Backstage lighting” systems would include, but not be limited to:

  1. Cue lights
  2. Work lights
  3. Running lights

 

A DMX terminator is made by placing a 110 ohm, 1/4 watt resister on pins 2 and 3 on the connector.  Terminators typically go at the end of a string of DMX devices.

Please refer to previous pages for the pin outs of a Soco connector and the wiring of a stage pin connector.