Model Centre adaptor converts E24 sockets to Next18 for Heljan TT:120

The Model Centre (TMC) has developed a compact adaptor harness that converts an E24 decoder interface to a Next18 socket, widening decoder choices for Heljan TT:120 models. The adaptor plugs into an E24 socket and provides a female Next18 connection via a short ribbon cable, allowing Next18/Hornby HM7000-style decoders to be used in models originally fitted with E24 sockets.

TMC revealed the new part on January 27, 2026, positioning it as a practical bridge between Heljan fitments and the popular Next18/HM7000 decoder family. The adaptor is a male E24 plug mated to a female Next18 socket, connected by a short ribbon cable so the decoder can be positioned away from the chassis or socket for clearance and neat wiring. That simple hardware layout makes the adaptor useful where space, weight distribution, or original circuit boards have limited access to a Next18 board.

The specificity of the adaptor matters because Heljan’s TT:120 powered models commonly use E24 interfaces that are not electrically compatible with Next18 decoders without modification. By providing a direct physical and wiring interface, the adaptor lets modellers fit Next18 decoders that follow the HM7000 style without cutting traces or rebuilding harnesses. That expands choice of sound and non-sound Next18 modules for TT:120 locomotives and can save time on conversions.

TMC has opened pre-orders for the adaptor in both single and triple packs, with pricing listed in GBP. The single and triple pack options are intended to suit one-off conversions as well as fleet upgrades. For fuller product details and to place orders, see The Model Centre product page.

Beyond immediate conversions, the adaptor is likely to be handy in workshop swaps and test-bedding decoders before committing to permanent installation. Placing the decoder away from the socket with the ribbon cable also helps when adding sound decoders or auxiliary wiring that needs room for speakers or capacitors.

For modellers running Heljan TT:120 stock, the adaptor provides a practical, low-friction way to access the broad Next18 decoder ecosystem. Expect keen members on forums and club tables to post fit photos and wiring tips as pre-orders start to ship, and check the Model Centre product page for availability and any fit notes specific to particular Heljan models.