Transformer Coil – What is it in Vaping?

Definition

A Transformer Coil is a specialty rebuildable atomiser coil whose outer wrap is electrically isolated from the inner heating core, letting the core heat the outer wrap through induction instead of direct current. The result is a coil that changes resistance while you vape, giving smoother ramp-up, cooler legs, and denser vapour without scorching wicks. Popular with hobbyist vapers who enjoy tinkering with Temperature Control (TC) and want a “self-regulating” build in any standard tank or dripper.

Technical Details

The build uses two distinct wire circuits: an inner “primary” core (usually Ni80 or SS316L, 24–28 AWG) and a floating “secondary” outer wrap (30–38 AWG Kanthal or Titanium Wire). Only the primary is connected to the deck; the outer wrap is anchored at one post but electrically cut off at the other, forming an open loop. When current flows, the primary heats and induces eddy currents in the outer wrap, causing it to glow milliseconds later. Typical specs: 3–4 mm internal diameter, 5–7 primary wraps, 8–12 secondary wraps, final resistance 0.12–0.25 Ω on a dual-battery mod. Variations include Clapton-style transformers, staggered transformers, and micro-transformers for single-coil Top Fill RTAs.

Usage & Tips

• Mount the secondary tail with a tiny silicone bead or trimmed nail polish to ensure it stays electrically isolated; a short to the deck will kill the effect.
• Pulse at 25–30 W to check glow: primary should heat evenly, secondary should follow 0.5–1 s later. Stray hot-spots mean you need tighter outer tension.
• Wick snugly but not tight—cotton collapse chokes the outer wrap and kills vapour density.
• Transformer coils run cooler on the legs, reducing Throat Hit harshness, yet still chuck clouds; start 10% lower than your usual wattage.
• Never lock TC with a transformer build: the resistance rise is intentional, not a temperature signal.

History & Context

The concept emerged on Australian Facebook groups in 2019 when coil smith “AussieInduction” posted a video of a glowing secondary wrap with no second leg. Within months, local builders commercialised pre-wound transformer coils, and the design spread worldwide as a “next-gen” hobby build that marries mechanical simplicity with exotic performance.