TTS Sound Decoder: Class 20

TTS Sound Decoder: Class 20


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TTS Sound Decoder: Class 20


Item Code: R8118

sssss (1 review)

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| Description

IMPORTANT - The decoder does not support sound under DC (analogue) operation. Sounds can only be played under DCC (digital) operation. This applies to all sounds, both running and spot sounds. The locomotive's motor may be controlled under DC operation.   

Function list

  • F0     Headlight/rearlight
  • F1     Engine start/stop
  • F2     Horn high-low
  • F3     Horn low-high
  • F4     Brake squeal
  • F5     NOTCH up
  • F6     NOTCH down
  • F7     Return to IDLE
  • F8     Thrash
  • F9     Cold start override
  • F10   Horn high two bursts
  • F11   Door slam
  • F12   Fan
  • F13   Horn long high
  • F14   Horn low two bursts
  • F15   Primer
  • F16   Slow flange squeal
  • F17   Spirax valve
  • F18   Horn low
  • F19   Horn high
  • F20   Wagons buffering
  • F21   Wagons clanging
  • F22   Coupling 1
  • F23   Guard's whistle
  • F24   Coupling 2
  • F25   Aux (if used in locomotive)


- Supports short and long decoder addresses
- Adjustable acceleration and deceleration
- Back EMF load compensation
- Up to 19 controllable spot sounds dependent on model including whistles or horns etc
- Two sound channels allowing for simultaneous play of full locomotive engine sounds, & individual spot sounds e.g. horns, whistles, brakes, wagons coupling etc. NOTE: Only one spot sound can be played at the same time
- It is possible to alter the volume of each sound through an individual dedicated CV. Range 0-8
- Decoder is equipped to support directional front and rear lighting operation via F0 on the controller, providing that the product is fitted with lights
- The decoder is equipped with 1 aux function output controlled by F18 or F25 dependent on locomotive type (diesel or steam)
- Motor current - maximum continuous 500mA
- Motor current - peak 1amp (no function load)
- Function output current maximum—100mA (unprotected)
- Decoder current maximum continuous - 800mA (shared motor and functions)
- Number of sound channels - 2
- Termination - 8 pin plug NEM652. NMRA


Hornby is a household name and is famous as the UK's brand leader in the model railway hobby with its high quality 00 gauge (1:76) models and accessories.

% Safety Notice

Colour and contents of products may vary from those illustrated

y Technical Specification & Detail

Age Suitability 14+

* Customer Reviews Review Guidelines



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sssss 4

Hornby Class 20 TTS Sound Decoder

A very good decoder. I found that the speaker is too big and hence used a smaller 8 ohm speaker. A bachmann Class 20 has very little space. The yellow and white wires work well for the front and rear lights. But I am struggling with the green wire (Auxiliary) which I wish to use for the Cab Light. It does not work! I have checked the connections. I am using a SMD 805 LED with a 1K 0603 SMD resistor for the cab light. Rest of the LEDS are SMD 0603 with 1K SMD 0603 resistors

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