Sunday, September 01, 2013

Adding a sound module to a battery loco

After some deliberation, I decided it was time I experimented with adding sound to at least one of my battery locos. As she was the loco which was on the workbench at that particular time, I decided to investigate options for adding sound to the IP Engineering 'Jessie' kit which I had recently completed (see How I constructed an IP Engineering diesel kit).

After exploring various alternatives, I contacted Peter Spoerer by email and he suggested I gave him a ring to hear his latest narrow gauge diesel sound module. After a few minutes I was convinced that his unit was just what I needed for 'Wynford' as 'Jessie' had now been re--christened.

A couple of days later, a small parcel arrived containing the bits I needed - the sound module, a radio controlled switch and a small loudspeaker. Although the kit comes with a loudspeaker, I opted for a smaller 'laptop' unit in its own housing which I felt would be easier to fix into place.

The first thing I did was to fix the speaker to the inside of the cab roof with a double-sided sticky pad.

Once the problem of siting the speaker had been solved, I ran the wire through to the front part of the loco where I was hoping there would be sufficient space to add the electronics alongside the NiMh batteries, the Brian Jones Mac Five speed controller and the Deltang receiver.

The wiring for the unit was extremely straightforward and very logical. Two wires (red and black) were connected to the battery feed for the controller, to provide power the module, another two wires were connected to the feed for the motor (yellow and blue) to sense the speed of the loco. Two wires (red and black) were connected to the speaker and another two wires (white) were connected to the radio controlled switch which is used to control the horn and to start-up and stop the sound unit. From the switch a plug is connected to one of the channels of the receiver (in my case channel 3). There is a volume control on the module - I set mine to about 85% of full volume.

After testing the unit (it worked first time!!), the next job was to try and cram everything into the space left under the bonnet of the loco. I neatly coiled the wires and then held everything in place with a few strips of masking tape.

The wires from the controller were plugged into the leads for the loco's headlight and the bonnet was then carefully screwed into place.

 This took a couple of tries but eventually, the loco was back on the rails for some trialling.

 The start-up and wind-down sounds of the engine are excellent. The transition from tick-over to running sound is dictated by the unit which presumably senses the input to the motor and moves in a predetermined way from one to the other. As the sounds are real recordings of a diesel loco, the sound is not directly linked to the speed of the loco, but once under way the engine noise is quite appropriate for a loco which generally tends to run fairly slowly.

As you can hear from the video, the sound module is extremely effective and to my mind well worth the investment. I am now more determined to add sound to my other battery locos - as soon as funds permit!

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