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SFX21+ Diesel Loco Sound Capsule

  • Price : £45.00
  • Model Number : SFX21
  • Availability : In Stock Now
  • Overall 5/5 ( reviews.)
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The SFX 21+ is a new variation on the popular SFX20+ with exactly the same sounds except that there is no silent coasting so the engine sounds continue and the two tone horn sounds after it has been running for a while. 

Sounds include turbo whine, air horn etc

Easy to fit in seconds - no wiring or switches!

• No pickups or wires - works on regular DC & DCC

• Self contained capsule - built-in speaker & battery

Tiny - smaller than a 50p: 25mm x 20mm x 12mm

• Fit capsule into a loco, tender, wagon, coach...

• Plus version has facilities for volume setting, external speaker & battery

How to fit SFX Sound into N Gauge guide, see here 

How does it work?

At the heart of each SFX is a microchip containing the real recorded train sounds and a small motion sensor which detects what the train is doing and replays the most appropriate sounds through the tiny loudspeaker. The motion sensor also turns on and off power so that there is no need for any switch and battery life is preserved.

SFX21 Classic Diesel Loco Sounds - no coasting

These are the sounds you can expect to hear from your SFX21. They are not simulated effects but real sounds recorded by us from Class 31 locomotives No D5631 (31207) on the North Norfolk Railway ( and No 31235 on the Mid Norfolk Railway (

  • Stationary - Engine Tickover sound and the occasional compressor noise cutting in and out
  • Any movement triggers the sound of air release and if motion continues a single horn sounds followed by gradual speed up of the engine
  • After speed up engine power is maintained
  • The two tone horn sounds after the loco travels continuously for a while
  • When motion stops it returns to stationary sounds.
  • If there is no motion for over a minute the SFX automatically goes to sleep and waits for slight movement to wake it up.
  • Pack includes SFX, Sound Tube, Battery and instructions 

      You can see a video of the SFX21 capsule and its sounds by Clicking Here

    Battery Info:

    • Uses CR2032 battery - readily available from dcpexpress or Train-tech dealers as BAT1(Click Here) at just £3 for a pack of 3 and will last most people years!


    Lithium type batteries cannot legally be mailed internationally by Royal Mail or their partners in other countries, so please do not order this item if you are outside the UK or Northern Ireland as we will have to remove the battery before shipping. 

    DCP Express offer all of its products without batteries at reduced prices for sale to our international customers. Our apologies for this inconvenience, but you should be able to buy these standard CR2032 batteries quite easily in your own country.

    The following range of SFX Sound Capsules now available:

    SFX10+ Steam Express sound capsule Click here

    SFX11+ Steam Freight sound capsule Click here

    SFX20+ Diesel Sound Capsule - with coasting Click here

    SFX21+ Diesel Sound Capsule - no coasting Click here

    SFX50+ DMU Diesel Multiple Unit Sound Capsule Click here

    SFX70+ Goods Shunting Sounds Capsule Click here

    SFX80+ Passenger Coach Sounds Capsule Click here

All prices shown INCLUDE UK VAT at 20% and a VAT receipt is automatically supplied. (VAT not charged to non UK customers and will be automatically removed at Checkout)
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DCP Microdevelopments have been established for 40 years and are proud to design and manufacture all of its own products in Great Britain

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