Steam sound on a tight budget

[bertiedog]

I intensely dislike DCC sound, it is tinny and very very expensive, unless it comes free on a second hand loco from Ebay!

 

I have tried some electronic sound circuits many times in the past, but I felt an experiment may be worthwhile with the small Velleman steam sound generator kit, MK 134.

 

It features potentiometers on the volume and rate of the steam chuffs, and the idea is to fit optical light dependant resistors to the board in place of the potentiometers.

 

The power from the track will be fed to two LED lamps fixed to each LDR, and as the 0 volts to 12 volts is applied, the volume and rate should increase/decrease in proportion.

 

In practice the range should be about 3 volts to about 9 volts to get the LED to function, and the max sound speed to occur well before max speed.

 

I am investigating the exact circuit Velleman use, and will try to work out if the LDR has the range etc. It may need padding to get a working value.

 

The speaker remains below the layout of course, the board is too large for a loco, even a big tender.

If the scheme fails, then a mechanical attachment to the model controller could be used.........

 

Stephen.

[cliff park]

You need to know the value of the potentiometer in the original circuit, and whether it is wired as a potential divider or a variable resistor. If the latter it may be hard to match the values and range.

[baconbutty]

You need to know the value of the potentiometer in the original circuit, and whether it is wired as a potential divider or a variable resistor. If the latter it may be hard to match the values and range.

The speed pot is 100k and the volume pot is 5k. Both are wired as variable resistors.

 

Assembling the circuit is still on my to do list!

 

Hope that helps.

Ollie.