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In the model railroad business since 1998

Product Image Digitrax DH165Q1 1.25 Amp HO Scale Mobile Decoder

Digitrax DH165Q1 1.25 Amp HO Scale Mobile Decoder



DH165Q1 fits Atlas, Intermountain, LifeLike & Other factory sound-equipped HO Locomotives.

Compatible with Digitrax Sound Bug.

Decoder Lock equipped

  • QSI-style PCB replacement Plug N’Play decoder-
  • Allows replacement with new technology downloadable SFX SoundBug modules
  • Accepts Plug-in SFX SoundBug sound modules
  • Excellent power management-
  • Booster or Programmer overloads
  • Regulated Headlights: convenient no-resistor install of LEDs and lamps.
  • Digitrax LocoMotion® System-
  • Your locomotives look like the real thing. The Digitrax LocoMotion System makes them run like the real thing, too!
  • Torque Compensation for smooth as silk silent operation.
  • 128 Speed Step operation (14 or 28 steps can also be used).
  • Momentum with acceleration and deceleration.
  • Normal Direction of Travel is user selectable.
  • 3 Step Speed Tables set start, mid and max voltage for custom control.
  • 28 Step Speed Tables with 256 level resolution for precise control.
  • Scalable Speed Stabilization with simple setup & 1024 level resolution.
  • SuperSonic motor drive for silent operation.
  • FX3 Functions for prototypical lighting effects:
  • Constant Brightness Lighting directional or independent control.
  • Realistic Effects like Ditch lights, Mars lights, strobes, and many more.
  • Dynamic and Static Qualifiers operate functions based on direction, F0 on or off, loco direction and F0, and whether loco is moving.
  • Function Remapping for custom function setup.
  • Master Light Switch turns off all lights & functions with one keystroke.
  • Advanced Consist Function Controls
  • Transponder equipped ready for transponding on your layout.
  • Compatible with digital surround sound systems
  • All Mode Programming with Operations Mode Read Back-read back CV values right on the mainline.
  • Decoder Factory CV Reset with or without speed table initialize.
  • Motor Isolation Detection prevents damage to your decoder.
  • Basic, Advanced & UniVersal Consisting
  • 2 Digit and 4 Digit Addressing


 Current Rating-Motor 1.5 Amp (2.0 Amps Peak)
Size 2.877” x .667” x .173” (73.07mm x 16.93mm x 4.4mm)

These decoders are made to fit specific locomtoive chassis.  Locomotives that have circuit boards that can have decoders installed in place of the original circuit board are made by many manufacturers.

In some cases, locomotive modifications, motor isolation and additional soldering may be required during installation of this type of decoder.  Function leads can be added to these decoders using solder pads available on the decoder.

See the instruction sheet for the particular decoder you are using for specific instructions.

Sometimes these are called plug n' play or drop in decoders.

Function Outputs


Function Type

Digitrax Real FX3

  • Turn functions on and off. 
  • Head lights and tail lights are automatically reversing unless you make them independent. 
  • All function outputs have FX generators for prototypical lighting effects and have qualifiers for FX effects and qualifiers for standard on/off functions.
  • All Digitrax Series 3 decoders have FX3 type functions.
  • FX3 decoders offer full function mapping so you can choose which function (F0-F12) controls each function lead.
  • FX3 decoders offer master light switch capability.
  • FX3 decoders offer qualifiers for FX function operation qualified by one of the following:  the loco's direction of travel, whether F0 is on or off, loco direction and F0, or whether the loco is moving or not. These qualifiers are also available on function outputs that are used as standard on/off functions.

Series 4

First generation SoundFX decoders

Most are mobile, sound and function decoders, some are sound and function only decoders.

For Use With

Sound Bug Sound Only Decoder


Digitrax gives a one year "No Worries"Warranty against manufacturing defects and accidental customer damage

on all Digitrax command stations, boosters, throttles, decoders, power supplies and layout control devices.