Sound effects

[duncan webster 1Participant @duncanwebster1]

My latest creation is a battery electric model of an LNER Y3, which as you all know was a geared steam loco. What I’d like is some electronic gizmo that would emit a single chuff sound every time it was supplied with a pulse, and a second channel for a steam whistle. I can then put a sensor on an axle to generate 6 pulses per rev. I’ve tried emailing Mtronix but no reply. Anyone got any bright ideas?

[Stuart Smith 5Participant @stuartsmith5]

Possibly this one would work as you want or could be modified to:

https://www.mylocosound.com/mylocosound_029.htm

I have no experience of these, have just seen them on the internet.

Stuart

[Peter Cook 6Participant @petercook6]

How about one of these and a bit of wiring. Claims 2Meg of storage for sounds & 8 different trigger pins to set off the sound. Probably needs an amplifier and speaker for your use, but looks fairly straightforward.

Sound effects can be downloaded from the internet.

[duncan webster 1Participant @duncanwebster1]

Peter’s looks good, any sound I like. The start of a new learning curve. Keeps the grey matter going doesn’t it.

I’ll post with success or failure, but don’t hold your breath, wife has had new hip so I’m head cook and bottle washer, no workshop time, hence my postal diarrhea recently.

[duncan webster 1Participant @duncanwebster1]

I’ve bought the thing recommended by Peter, and down loaded some suitable noise as wav file. Now I need an amplifier (I assume). I’ve been given an 8 ohm 12W speaker 3″ diameter (tweeter?), and I’ve found a bewildering array of amplifier boards, all less than £5, but only a few quote the speaker resistance. Any audiophiles out there got a recommendation? I suspect the TPA3110 based devices are the ones, but it’s all Greek to me

Is 10W enough, remembering it’s outdoors? If not do I just buy another speaker and use a stereo amp?

[duncan webster 1]

On duncan webster 1 Said:

[…]

Is 10W enough, remembering it’s outdoors? If not do I just buy another speaker and use a stereo amp?

It is a stereo amp

… also useable as a bridged mono amp if you prefer to use one bigger speaker.

I’s also Class D … which means it’s very simple to implement, but of no interest to ‘Audiophiles’

… Looks ideal for the job at hand.

MichaelG.

[duncan webster 1]

On duncan webster 1 Said:

… I’ve found a bewildering array of amplifier boards, all less than £5, but only a few quote the speaker resistance. …

Is 10W enough, remembering it’s outdoors? If not do I just buy another speaker and use a stereo amp?

Odd that many of these modules don’t quote the speaker impedance, I guess due to the chip used.   Not an analogue amplifier running on a fixed voltage as I’m used to, rather a Class D device powered by anything between 6 and 40V.   Speaker impedance is related to voltage, so there isn’t a single answer.   One datasheet says use a 3.2ohm speaker on a <=15V supply and an 8 ohm speaker when the supply is above 15V.  I doubt it’s critical unless the amp is run flat out.  If worried about blowing the speaker or amp go up in ohms rather than down.

10W would be plenty except Speaker efficiency tends to be low, less than 2%. (Unless I’m out of date!)   A full orchestra peaks at about 10W out so a 500W amp would be needed to replicate it with a 2% speaker system.   This application needs much less power – an orchestra at full blast is loud!   On the other hand, the speaker is outside, so the volume enhancement due to reflection inside a room is lost.

In my youth Tannoy systems had efficient but horrible sounding speakers, amongst other distortions they couldn’t do high frequencies.  But maybe a PA system speaker would be better for this application than an audiophile’s delight.   One of those horn-speakers used in steam age railway stations could be ideal!

I’d rather use a single 20W amp than a pair of paralleled 10W stereo channels, because the wiring is slightly simpler.  Might be prejudice!

If two speakers are used make sure they are wired in phase, otherwise the sound cancels.  (I hear incorrectly phased speakers more as a deadening than loss of volume.)

Bottom line, I think it necessary to experiment.  Speakers should be aimed, so play with position.  I guess a 10W amp into a 2% speaker will be on the low side outdoors, and because many speakers are less than 2% efficient, a bigger amp will be needed.   Oh, and specs often quote Input power, so an amp needing a 10W power supply will be rather less audio out.

Dave

 

[Grizzly bearParticipant @grizzlybear]

Hi,

https://www.picaxeforum.co.uk/threads/model-train-sound-and-light-program-advice.30098/

 

Good luck………

[duncan webster 1Participant @duncanwebster1]

I tried to open that, but it appears to be full of text formatting? Lots of reference to colours.

[Michael GilliganParticipant @michaelgilligan61133]

Have you got-to-grips with that TPA3110 data-sheet yet, Duncan ?

MichaelG.

[duncan webster 1]

On duncan webster 1 Said:

I tried to open that, but it appears to be full of text formatting? Lots of reference to colours.

Sad innit.  Someone cut and paste picaxe BASIC source into another forum and in doing so the normally hidden colour scheme used to highlight syntax has obliterated the underlying source code.  Difficult to clean up!

This forum is no better because it too mangles source code!  Best answer, unless anyone knows better, is to publish source as an image and use git, dropbox or similar to make the original program available as plain text.

And having done that Duncan may not be familiar with picaxe.  Why is nothing ever easy?

Dave

 

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