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This is a preloadable soundfile for your chosen Zimo decoder purchase. Cannot be bought on its own.

Please note this video shows the activedrive version of the file.



Heljan Class 128 Digidrive E V3.0.

We know that you will want to try out your new sound project immediately – we are modellers too!

There are some unique control features which require a little explanation.

Please spend a few moments to read these notes which have been produced so that you may obtain the maximum satisfaction from your new sound scheme.

The sounds should work perfectly when the decoder is fitted correctly. Individual models may require some fine tuning that you can achieve with your DCC controller.

What is DigiDrive E?

This is a system developed to allow more prototypical sounds to be deployed across a wide range of operating conditions.

The sounds have been programmed in such a way that you, the user, may change the way that the sounds respond to your driving style or needs. This avoids the need for reprogramming and all the additional costs that would imply.

Please note

Some of the new controls will not operate correctly if you use 14 or 28 speed steps. Please ensure you use 127/128 speed steps to get maximum advantage of these important additions.


Throttle Response Scheme, Driving Tips

As supplied, the decoder will produce the typical sounds of a unit ready for work.

Use F1 to start the engines. These units car have two engines which are started sequentially. After both engines have started the unit will stand with the diesel engines ticking over at idle.

Occasionally, if standing, the driver will increase the engine revs to drive the compressor for more air pressure. This compressed air is to operate the controls, not the brakes which function via vacuum.

These units had four gears, operated manually via Electro Pneumatic valves (EP Valves) which give the characteristic double hiss. After accelerating in each gear, the engine was required to spool down to more closely match the speed of the gearbox. This is why there is a characteristically long pause during gear changes.

Furthermore, the real units were only capable of coasting when in direct drive, 4th gear. When a period of coasting was anticipated (‘Know The Road’) if not already in top gear, 4th would be selected by the driver.

This sound project is designed to simulate all of these characteristics automatically, including the compressor speed-up in standing. But in order that the model is usable on all types of layout, some manual intervention is possible to modify the automatic sounds.

After a little practice you will find these ‘over-rides’ substantially increase the accuracy of the simulation possible, and the satisfaction gained.

The sounds will respond to the throttle control in the following way:

Automatic sequence

Select speed step 1. The engines will increase power to get the unit moving and will continue acceleration sounds until they reach maximum permissible revs. At this point, the engines will spool down ready to select 2nd gear. However, it will not be possible for the gear to change until the unit achieves a scale road speed of approximately 15 MPH (around speed step 36) and so the engines will ‘idle’ between speed steps 1 and 35. Similarly, to achieve the following gear change, the road speed must be approximately 27 Scale MPH (speed step 50), and 4th gear at 41 MPH (speed step 64). At this point the unit will cruise at a steady engine power. These points are all contained within the project, but the actual speed steps May vary slightly depending upon your controller and model.

In practice, this means that if you increase the speed steps to 64 in a smooth progression, the unit will increase in speed and provide realistic acceleration and gear change sounds.

Manual over-ride

However, you may not have sufficient length of clear track for all of the above to take place, so I’ve built-in the ability to ‘cheat’ a little if necessary.

If you find the unit travelling with engines idling and you are not purposely intending to ‘coast’ the following options are available.

  1. Engage F7. This will produce an immediate gear change followed by constant cruise sound. (Disengage to return to idling)
  2. Engage F8. This fades into a slightly slower cruise sound without gear change as would be expected when re-applying power to a unit which is coasting. (Disengage to return to idling)
  3. Reduce speed step by one, using your throttle control and immediately increase by one (or more). This will not have a visible effect on the road speed, but will instantly create a gear change and acceleration sound. Adjust speed accordingly.


Option 3 allows you to force gear changes as often as you wish, at any speed as long as the decoder is not already playing an acceleration sound.

The F6 key will hold the engines in idle, whatever your road speed. This can be useful to ‘lock’ the automatic sounds if you wish vary the speed without gear changes being triggered, eg varying speed whilst cruising, hold idle when stopping to prevent gear change and acceleration if you find you are stopping a little short and need a small burst of (quiet/covert) acceleration to rectify the problem.


Notwithstanding the F6 feature, there is another way to coast and decelerate with the appropriate sounds playing. It works in a different way and has slightly different outcomes.

From any speed, if you reduce speed steps the automatic sounds will revert to ‘engines idling’ if not already playing. This provides a convenient coasting control.

 Provided you send no acceleration commands, you may continue to reduce speed all the way to zero in coast mode, just as a real DMU would be driven. (Since F7 and F8 are manually controlled, remember to disengage them before decelerating).

Light Loaded Mode

In this, Version 3, there is an added feature.

These vehicles are relatively lightweight and their power units are just about adequate for their purpose. As a consequence, their performance is very dependent upon loading and gradients.

Most other DMU sound projects ignore this reality and provide a ‘one size fits all’ solution.

We constantly endeavour  to match reality ever more closely, so now you can choose to run your DMU lightly loaded or full of passengers, uphill or down.

By default, the decoder will simulate a heavy loaded train, or one starting on an adverse gradient. The acceleration rate will be retarded due to the high inertia, and the 1st gear acceleration sounds will be drawn out as the units struggle for speed.

To simulate a lightly loaded unit, or one starting on a down gradient, engage F key 5 before opening the throttle. Performance will be transformed. Inertia is reduced so acceleration is rather more brisk and the 1st gear acceleration sound is shorter, reflecting the earlier gear change possible.

Similarly the heavy unit will take longer to come to a halt due the high momentum; F5 will allow a ‘light’ train to stop more quickly.

It’s now down to your skill and knowledge to simulate any eventuality!


User Sounds

Some of the F keys play one sound when switched ‘On’ and a different, complementary, sound when switched ‘Off’.



Function list.

F0                           Lights on/off
F1                           Engines start up/shut down
F2                           Hi-Lo horns (hold to extend first tone)
F3                           Lo-Hi Horns (hold to extend second tone)
F4                           Hi-Lo horns (hold to extend second tone)
F5                           Light Loaded Mode
F6                           Hold engines at idle
F7                           4th gear cruise
F8                           Engines at cruise
F9                           Flange squeal (adjustable length)
F10                         Guard’s Whistle
F11                         Cab Lights
F12 On                  Driver’s door opening
F12 Off                 Driver’s door closing
F13 On                  Driver’s window opening
F13 Off                 Driver’s window closing
F14                         Windscreen Wipers
F15                         Handbrake applied
F16                         Air tanks drained
F17 On                  Guard’s buzzer
F17 Off                 Driver’s response
F18                         Shunt Mode
F19                         Fade All Sounds


Paul Chetter


29th November 2014

Delivery & Returns

Delivery & Returns

If returning any product please can you ensure you send it back to us with proof of purchasing, a covering letter and contact details. See terms and conditions for full information on our returns policy.