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This is a premium soundfile for your chosen Zimo sound decoder purchase. Cannot be bought on its own. Does not include decoder. Also available as a reblow or coded download please call.




This is a premium soundfile for your chosen Zimo sound decoder purchase. Cannot be bought on its own. Does not include decoder. Also available as a reblow or coded download please call.

ZSDMUA 1st Generation DMU ActiveDrive 5 functions V18.03.

This instruction set is standard for the types 101, 108 and 121 DMUs The light settings are suitable for the Dapol model.

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 ActiveDrive?

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.

Throttle Response Scheme, Driving Tips

As supplied, the decoder will produce the typical sounds of a first generation DMU ready for work.

Use F1 to start the engines. Each power car has 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 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.

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 and so the engines will ‘idle’ between gears. Similarly to achieve the following gear change, the road speed must be approximately 27 Scale MPH and 4th gear at 41 MPH. 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.

Manual engine sound selection

If driving below the speed that engages 4th gear or backing off one speed step the engine revs will drop to idle and you can choose to cruise using F7 to raise the revs a bit to maintain a medium speed.

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.

F6 forces the sound to idle only allowing you to move the vehicle short distances without a full acceleration sound, lift the revs with F7 for these types of positioning or shunting moves. Release F6 and 7 before setting off on a service train.


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. 

Light Loaded Mode

In this version 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 train, 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 train will take longer to come to a halt due the high momentum; F5 will allow a ‘light’ train to stop more quickly.


F2 is the Brake Key which can be ‘dabbed’ or held for varying durations. There is little sound as they are vacuum brakes.

If the throttle is reduced in advance, as a real driver would do, before operating the Brake Key, a braking force will be applied which will continue to increase the longer F2 is held. Short dabs will provide speed trimming, held down continuously will result in a controlled ‘Emergency Stop’.

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

User Sounds

I remember these vehicles as having noisy engines, squealing wheels, slamming doors with drop-light windows and external door knobs. They seemed to be forever accelerating, coasting and stopping in an endless cycle.

So that’s what I’ve modelled into the sound file. Some of the F keys play one sound when switched ‘On’ and a different, complementary, sound when switched ‘Off’. This helps to expand the number of different sounds available. 

Function list.

F0                           Marker lights on/off
F1                           2 Engines start up/shut down
F2                           Brake Key
F3                           Lo-Hi Horns (hold to extend second tone)
F4                           Hi-Lo horns (hold to extend second tone)
F5                           Light Loaded Mode
F6                           Idle only
F7                           Low revs for shunting or cruising
F8                           Guard’s Whistle
F9                           Flange squeal (adjustable length)
F10                         FO1 & FO2 cablights or interior lights if fitted
F11                         Double buzzer code
F12                        Single buzzer code, 
F13                         Driver’s door
F14                         Passenger door slams
F15                         Air tanks drain down                      
F16                      Handbrake applied
F17                         Windscreen wipers
F18                         Droplight window
F19                         FO3 Lights if fitted          

Digitrains March 2018

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.