6-Point Ignition Transformer

Ignition Transformer
Ignition Transformer

Here’s a quick teardown of an ignition transformer, used on gas fired ovens & hobs.  This unit takes mains 240v AC & uses a transformer to step the voltage to several kV, at a low current to ignite the burners.

Bottom
Bottom

The transformer section is completely potted in Epoxy resin for insulation, but the driver circuitry is exposed, with a pair of leads from the primary winding exposed

Driver PCB
Driver PCB

The drive is very simple. The incoming AC flows through a series resistor through a half-wave rectifier to charge up a 2.2µF film capacitor. Once the voltage on the capacitor reaches a certain level, a DIAC in series with the transformer primary fires, discharging the capacitor through the primary.
The current spike induces a very high voltage on the secondary winding, this then arcs across a gap in the gas flow to start ignition.

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