I always had it in the back of my mind to add sound to this loco, but didn't want to do anything until I had it running satisfactorily. So, now that it is, sound was next on the agenda. Commercial soundcards are expensive and relatively bulky and space is at a premium so I decided to take inspiration from Rik ( Again! Thanks Rik) and play around with a DF Player Mini.
I won't bore everyone with my trials and tribulations getting it working because they were mainly to do wth my own incompetance, however what I wanted to do was have two sound tracks on the micro SD card, one being a "start up, moving off and running" track and the other being a "slow down and stop".
I searched high and low on the 'net but couldn't find what I wanted so in the end I set up another loco with an MLS sound card in it, on a rolling road, and recorded that doing the sequences that I wanted. I then opened the file in Audacity and firstly I copied the last 10 seconds of the clip and saved that separately then deleted it from the original. I then played around a bit with the main clip until I had the sequence that I wanted. This "running" clip was only about 90 seconds long at this point, so I copied it multiple times and joined them end to end until I had a clip that lasted about 20 minutes. That should last for approximately 2 complete circuits of my line without stopping. I then took the saved end clip and modified that slighly and re-saved it. I have read in several places that DFPlayer gives a smoother transition from one track to another with .wav files rather than .mp3, so the originals were saved as wav's and played back perfectly. However after the editing in Audacity, although they play perfectly in that program and VLC Player, and even Windows Media Player, the DF Player doesn't like them and just gives a strange "Bleuw" noise. After much mucking about and getting nowhere, in desperation I resaved both clips as mp3 files and DF Player plays those perfectly - I have no idea why the difference?
Anyway, I now had to get DF Player to play nicely with the loco and Deltang Rx65b.
I have 6x AA Low self discharge NiMh batteries in the loco, which when fully charged push out a smidgeon over 8v, which is perfect for the Rx but the DF Player wants 5v or slightly less, so I rummaged in my bits box and came up a small variable voltage regulator board and set it to give 4.5v. By happy chance, this board just fits between the connection pins on the player so the two together make a nice neat little self contained package.
- IMG_0504.jpg (1.52 MiB) Viewed 5205 times
The player has the ability to play many tracks plus various controls, depending on how it is wired but I only needed two. The first track ( start and run) play as soon as they are triggered by the Rx, the 'end' track is then triggered by sending a signal to the "Next" command on the DF P. This overides the track that is already playing so the loco sound slows down, comes to a stop and cuts out. Then sending the initial command again starts the main clip, etc. There is a slight click when it switches tracks, but it is faint and quick and I can live with it - might not even be noticeable to anyone else.
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Nolwyn Valley Tramway
