gregh
electronics, computers and scratchbuilding
[/font] These notes are only for people with some electronics experience.[/font]
I have built many loco sound circuits using discrete components or using Picaxe microcontrollers. For those not acquainted with The Picaxe, it is a small programmable chip that is programmed in a simple version of BASIC. They come in 6 different memory sizes, but I have only ever used the smallest – the 08M type. This costs about $A7, so under 4 pounds in the UK, I’d guess. I use them for both sound and motor speed control.
You need a simple ‘developmental kit’ to interface with your PC where you write and debug you programs.
This is the website: http://www.rev-ed.co.uk/picaxe/ < Link To http://www.rev-ed.co.uk/picaxe/</a></font> < Link To http://www.rev-ed.co.uk/p...lt;/a></font>
The Picaxe includes a white noise generator (SOUND command) which can be used to simulate both diesel engine and steam chuff sounds.
These are some of the sound systems I've built from simplest to most complicated.
A 555 square wave oscillator for the simplest ‘diesel’ sound :
http://www.youtube.com/user/sandstonetermite#p/a/u/0/WAWgXCok7fU < Link To http://www.youtube.com/user/sandstonetermite#p/a/u/0/WAWgXCok7fU < Link To http://www.youtube.com/us...te#p/a/u/0/WAWgXCok7fU
The throb rate is controlled by the voltage charging the timing capacitor or on control pin 5.
A simple picaxe steam sound is the Climax loco at the start of this video. [/font < Link To http://www.youtube.com/watch?v=LuggRRYx6bM < Link To " target=_blank rel=nofollow>http://www.youtube.com/watch?v=LuggRRYx6bM</a></font> < Link To http://www.youtube.com/wa...lt;/a></font>
The steam chuff is just the white noise output from the SOUND command turned on and off at a rate determined by the motor voltage, so it is a very 'harsh' sound with no attack or decay time. When the loco is stopped there is a constant 'hiss'.
In the 2nd half of the video, you can hear a combination of sound recorder for the engine starting and Picaxe for the idling and running; in the diesel railmotor. The horn is just a single tone generated by the Picaxe.
Generation of the diesel sound works on the principle of a shift register being clocked at a speed dependant on the loco speed and the last two bits of the register are Ex-ORed and fed back to the input. (virtually a “random” number generator.) I found that a 5-bit shift register sounds OK. This is easy to implement in code as a left shift of a register is just multiply a number by two.
The "Best" steam sound circuit I have built was from a Silicon Chip circuit which uses a reverse biased transistor base-emitter jn to provide white noise, and a diode as a ‘shaper’ for the chuff. It still only uses an LM324 quad amp and a power amp (LM380)
http://www.youtube.com/user/sandstonetermite#p/a/u/1/hfrYCSyiQh0 < Link To http://www.youtube.com/user/sandstonetermite#p/a/u/1/hfrYCSyiQh0 < Link To http://www.youtube.com/us...te#p/a/u/1/hfrYCSyiQh0
The "best" diesel sound a kit from Talking Electronics (see: http://www.talkingelectronics.com.au/ < Link To http://www.talkingelectronics.com.au/</a></font> < Link To http://www.talkingelectro...lt;/a></font> )
In this video the orange diesel has this sound system. The hood provides a good resonant cavity to give great volume.
http://www.youtube.com/watch?v=1O2HF3VmnD4&feature=channel < Link To http://www.youtube.com/watch?v=1O2HF3VmnD4&feature=channel < Link To http://www.youtube.com/wa...D4&feature=channel
It is always much harder to get good diesel volume as it has more low frequency components than steam sounds. I usually use an LM380 power amp for diesel sounds and LM386 for steam.
Most of my circuit have two volume levels, one for working hard and a quieter one for drifting downhill or similar. The volume is selected by either the picaxe program (where used) or manually via one of the RC channels.
I have used cheap sound recording chips to record sounds such as horns, whistles and off-track sounds (saw mill, cows moo-ing etc). A number of recorders are available from http://www.electronics123.com/ < Link To www.electronics123.com in the US.
I use the A96010 kit as it includes a small speaker which is useful for testing. see here: http://www.electronics123.com/s.nl/it.A/id.2837/.f for around $US8. It's about 1" square. But there are others so peruse the website!
It can record up to 20 seconds of sound, and stores this sound even when the power is removed from the unit. The buttons and other pins are well marked on the recorder board. The electret microphone is on the board. One button is pushed down to record the message. The LED turns on during this time. The other button just has to be momentarily pressed to replay the message. A second momentary press during playback will stop the playback. All you have to add is 5V DC power (not included).
I just download the sound file I need, and hold the unit up to the computer speaker and press record (REC). It picks up a bit of background noise, so if you want to eliminate this, unsolder the microphone from the board (while the power is off !). I connected 2 wires to my computer speaker and I just use a couple of jumper leads across to the microphone connections on the sound recorder board.
There are 3 ways to (re)play a sound.
1. You can just provide a 0V signal onto the Play button or,
2. You can short out the play button and just switch the 5V supply, or
3. Just press the Play button!
1. has the disadvantage that inadvertent pressing of the REC button will erase the existing sound, so really have to remove (unsolder) the Record button.
2. You have to turn off the supply at the end of the message or it will repeat forever (with a slight gap between the end and start). I usually record a sound with a few seconds of silence at the end, so I have that time to remove the supply.
If you DO want a 'continuous' sound, just make sure you remove your finger from the REC button as soon as your sound finishes playing on the computer. Then just connect 5V supply to the recorder board permanently.
Jaycar in Australia has a 120 sec sound recorder unit, but it runs off 3.3V which is hard to provide. (two NiMH cells are not enough and three are too high - the unit dies at 4V! I use a 5V supply and 2 diodes in series.)
A good plus is that it comes with a great little 40mm dia speaker which produces great sound.
For some more info, see my website at: http://www.members.optusnet.com.au/satr/electronics.htm#sound < Link To http://www.members.optusnet.com.au/satr/electronics.htm#sound < Link To http://www.members.optusn.../electronics.htm#sound
I have built many loco sound circuits using discrete components or using Picaxe microcontrollers. For those not acquainted with The Picaxe, it is a small programmable chip that is programmed in a simple version of BASIC. They come in 6 different memory sizes, but I have only ever used the smallest – the 08M type. This costs about $A7, so under 4 pounds in the UK, I’d guess. I use them for both sound and motor speed control.
You need a simple ‘developmental kit’ to interface with your PC where you write and debug you programs.
This is the website: http://www.rev-ed.co.uk/picaxe/ < Link To http://www.rev-ed.co.uk/picaxe/</a></font> < Link To http://www.rev-ed.co.uk/p...lt;/a></font>
The Picaxe includes a white noise generator (SOUND command) which can be used to simulate both diesel engine and steam chuff sounds.
These are some of the sound systems I've built from simplest to most complicated.
A 555 square wave oscillator for the simplest ‘diesel’ sound :
http://www.youtube.com/user/sandstonetermite#p/a/u/0/WAWgXCok7fU < Link To http://www.youtube.com/user/sandstonetermite#p/a/u/0/WAWgXCok7fU < Link To http://www.youtube.com/us...te#p/a/u/0/WAWgXCok7fU
The throb rate is controlled by the voltage charging the timing capacitor or on control pin 5.
A simple picaxe steam sound is the Climax loco at the start of this video. [/font < Link To http://www.youtube.com/watch?v=LuggRRYx6bM < Link To " target=_blank rel=nofollow>http://www.youtube.com/watch?v=LuggRRYx6bM</a></font> < Link To http://www.youtube.com/wa...lt;/a></font>
The steam chuff is just the white noise output from the SOUND command turned on and off at a rate determined by the motor voltage, so it is a very 'harsh' sound with no attack or decay time. When the loco is stopped there is a constant 'hiss'.
In the 2nd half of the video, you can hear a combination of sound recorder for the engine starting and Picaxe for the idling and running; in the diesel railmotor. The horn is just a single tone generated by the Picaxe.
Generation of the diesel sound works on the principle of a shift register being clocked at a speed dependant on the loco speed and the last two bits of the register are Ex-ORed and fed back to the input. (virtually a “random” number generator.) I found that a 5-bit shift register sounds OK. This is easy to implement in code as a left shift of a register is just multiply a number by two.
The "Best" steam sound circuit I have built was from a Silicon Chip circuit which uses a reverse biased transistor base-emitter jn to provide white noise, and a diode as a ‘shaper’ for the chuff. It still only uses an LM324 quad amp and a power amp (LM380)
http://www.youtube.com/user/sandstonetermite#p/a/u/1/hfrYCSyiQh0 < Link To http://www.youtube.com/user/sandstonetermite#p/a/u/1/hfrYCSyiQh0 < Link To http://www.youtube.com/us...te#p/a/u/1/hfrYCSyiQh0
The "best" diesel sound a kit from Talking Electronics (see: http://www.talkingelectronics.com.au/ < Link To http://www.talkingelectronics.com.au/</a></font> < Link To http://www.talkingelectro...lt;/a></font> )
In this video the orange diesel has this sound system. The hood provides a good resonant cavity to give great volume.
http://www.youtube.com/watch?v=1O2HF3VmnD4&feature=channel < Link To http://www.youtube.com/watch?v=1O2HF3VmnD4&feature=channel < Link To http://www.youtube.com/wa...D4&feature=channel
It is always much harder to get good diesel volume as it has more low frequency components than steam sounds. I usually use an LM380 power amp for diesel sounds and LM386 for steam.
Most of my circuit have two volume levels, one for working hard and a quieter one for drifting downhill or similar. The volume is selected by either the picaxe program (where used) or manually via one of the RC channels.
I have used cheap sound recording chips to record sounds such as horns, whistles and off-track sounds (saw mill, cows moo-ing etc). A number of recorders are available from http://www.electronics123.com/ < Link To www.electronics123.com in the US.
I use the A96010 kit as it includes a small speaker which is useful for testing. see here: http://www.electronics123.com/s.nl/it.A/id.2837/.f for around $US8. It's about 1" square. But there are others so peruse the website!
It can record up to 20 seconds of sound, and stores this sound even when the power is removed from the unit. The buttons and other pins are well marked on the recorder board. The electret microphone is on the board. One button is pushed down to record the message. The LED turns on during this time. The other button just has to be momentarily pressed to replay the message. A second momentary press during playback will stop the playback. All you have to add is 5V DC power (not included).
I just download the sound file I need, and hold the unit up to the computer speaker and press record (REC). It picks up a bit of background noise, so if you want to eliminate this, unsolder the microphone from the board (while the power is off !). I connected 2 wires to my computer speaker and I just use a couple of jumper leads across to the microphone connections on the sound recorder board.
There are 3 ways to (re)play a sound.
1. You can just provide a 0V signal onto the Play button or,
2. You can short out the play button and just switch the 5V supply, or
3. Just press the Play button!
1. has the disadvantage that inadvertent pressing of the REC button will erase the existing sound, so really have to remove (unsolder) the Record button.
2. You have to turn off the supply at the end of the message or it will repeat forever (with a slight gap between the end and start). I usually record a sound with a few seconds of silence at the end, so I have that time to remove the supply.
If you DO want a 'continuous' sound, just make sure you remove your finger from the REC button as soon as your sound finishes playing on the computer. Then just connect 5V supply to the recorder board permanently.
Jaycar in Australia has a 120 sec sound recorder unit, but it runs off 3.3V which is hard to provide. (two NiMH cells are not enough and three are too high - the unit dies at 4V! I use a 5V supply and 2 diodes in series.)
A good plus is that it comes with a great little 40mm dia speaker which produces great sound.
For some more info, see my website at: http://www.members.optusnet.com.au/satr/electronics.htm#sound < Link To http://www.members.optusnet.com.au/satr/electronics.htm#sound < Link To http://www.members.optusn.../electronics.htm#sound
