Tesla Bifilar / Longitudinal Coil Rig

Tesla's bifilar pancake coil for longitudinal wave transmission

$145 plan

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// Blueprint rendering available after purchase

Technical Specifications

Classification Scalar EM — Wave

Winding Bifilar pancake flat spiral

Self-Capacitance Dominant (no external cap needed at resonance)

Resonant Freq 100 kHz–10 MHz (coil-dependent)

Transmit Range Bench scale (1–3m demonstrated)

Drive Spark gap or solid-state Class-E oscillator

Difficulty 3 / 5

Est. Build Cost $200–$500

Est. Build Time 3–5 weeks

Overview

Tesla's bifilar pancake coil (Patent 512,340, 1894) is wound with two conductors in parallel on a flat spiral, connected so that current flows in opposite directions in adjacent turns. This cancels the magnetic (vector) component while maximizing the scalar (potential) component — the configuration Tesla used to investigate what he called "non-Hertzian" or "longitudinal" waves. This build plan covers precision flat-wind construction, resonance tuning via variable capacitor, and measurement of the near-field electrostatic standing wave pattern. A companion receiver coil and electrostatic detector allow propagation experiments at bench scale. The plan also covers the extended Tesla magnifier configuration where a third resonator is driven at higher harmonics.

Intended Research Use

Longitudinal electrostatic wave propagation, scalar field transmission experiments, resonant Tesla circuit studies, bifilar self-capacitance characterization.

Bill of Materials (15 components)

#Component

01 22 AWG enameled wire, 200m (×2 spools, different color)

02 Acrylic or bakelite flat winding form (30cm dia.)

03 Variable vacuum capacitor (10–500 pF)

04 MOSFET Class-E driver PCB

05 IRF510 MOSFET (×4)

06 Signal generator (1 Hz–20 MHz)

07 Air-gap spark gap (adjustable)

08 High-voltage probe (40kV rated)

09 Electrostatic field mill or Faraday probe

10 Ferrite bead choke (×6)

11 HV ceramic capacitors (1 nF, 5kV, ×8)

12 Grounding rod + copper braid

13 Fluorescent lamp (neon bulb) for field detection

14 Wooden or PVC winding jig

15 Digital frequency counter

Get Build Plan

Complete plan PDF including all specs, winding geometry, drive circuit schematics, measurement protocols, and Gerber files where applicable.

$145 one-time

Purchase plan — Stripe

Also available: Component kit $550 — members get 10% off

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Complete build documentation (PDF)

Winding specs + circuit schematics

Measurement + verification protocols

Sourcing guide for all BOM items

Lifetime access, no subscription

Build Difficulty

Intermediate — requires basic RF electronics experience.

Est. cost: $200–$500
Est. time: 3–5 weeks