Module 7: Physical & Electrical Engineering Deep Dive

Welcome to the Engineering Deep Dive of the Unilighter Course.

While the preceding modules focus on practical lighting design, stagecraft, and live software operation, this module is built for technicians, stage electricians, and systems engineers who want to master the hard physics, electrical rules, and digital protocol standards of stage lighting.

📑 Deep Dive Lessons

  1. Lesson 7.1: The Nature of Light & Optical Metrics

    • The electromagnetic spectrum, wave mechanics, and photon energy (\(E = h\nu = hc/\lambda\)).
    • Radiometry (Watts) vs. Photometry (Lumens): the CIE 1924 \(V(\lambda)\) photopic integral and \(K_m = 683\,\text{lm/W}\).
    • Solid angle calculus: Steradians (\(\Omega = 2\pi(1 - \cos(\theta/2))\)) and deriving Candela from conical flux.
    • The Inverse Square Law derivation from spherical wavefronts and Lambert's Cosine Law (\(E = \frac{I}{d^2}\cos\alpha\)).
    • Polar candela distribution curves (Type C goniophotometry) and GDTF photometric webs.

  2. Lesson 7.2: Stage Electrics, Power Distribution & Neutral Safety

    • Ohm's Law and the 80% continuous breaker derating rule.
    • Switch-mode power supply inrush currents (\(30\times - 50\times\) surge).
    • 3-Phase power balancing across \(L1, L2, L3\).
    • The non-linear LED hazard: Triplen harmonics (3rd harmonic at 150/180 Hz) and neutral conductor overheating.

  3. Lesson 7.3: The DMX512-A Standard & RS-485 Differential Signaling

    • RS-485 balanced serial transmission and common-mode noise cancellation.
    • Oscilloscope packet breakdown: Break (\(>88\,\mu\text{s}\)), Mark After Break (MAB), Null Start Code (0x00), 512 channel slots.
    • Bit timing (\(4\,\mu\text{s}\) per bit, \(44\,\mu\text{s}\) per 11-bit slot) and 44 Hz frame refresh budget.

  4. Lesson 7.4: Cabling, Characteristic Impedance & Terminators

    • XLR-5 vs XLR-3 connector pinouts.
    • The Microphone Cable Trap: Why \(45\,\Omega\) audio cables round off square pulses and cause intermittent flicker.
    • Transmission line characteristic impedance (\(110 - 120\,\Omega\)).
    • Wave reflections and why a \(120\,\Omega\) resistor absorbs electrical echoes.
    • Daisy-chain limits: 32 fixtures, 300 meters.

  5. Lesson 7.5: DMX Distribution: Opto-Splitters & Wireless DMX

    • Why passive Y-cables destroy high-frequency digital lines.
    • Galvanic opto-isolation: How a 2,500 V optical barrier protects consoles from high-voltage stage faults.
    • DMX Boosters and Mergers (HTP / LTP).
    • Wireless DMX (CRMX / W-DMX): Frequency hopping, latency, and line-of-sight propagation.

  6. Lesson 7.6: Network DMX: Multi-Universe Art-Net 4 & sACN (E1.31)

    • Overcoming the 512-channel ceiling with standard Gigabit Ethernet.
    • Art-Net 4: Net/Sub-Net/Universe addressing, Unicast vs Broadcast.
    • sACN (ANSI E1.31): Multicast addressing (239.255.x.y), IGMP snooping, per-universe priority (0–200) for seamless backup, and Universe Sync.