Never heard of this one.

Nick-

I remember some of the early TMCC diesels (and likely steam engines too) used a cherryswitch (aka microswitch) and a cam on one of the axles to trigger the engine sounds (diesel roar or steam chuff). Maybe you can adapt this for your application.

You can try using a thinner magnet, but if it is too weak the switch will not be triggered.

-John

There's  also   probably a small reed switch (stationary) that turns on & off triggered   by the magnet that activates the chuff.. the more magnets the higher the chuff rate.

 Can you find another spot for the rare  earth magnet . Would another rare earth  magnet help you..?. Pretty sure I have one or two you could have. There are about this size  O

If you put the magnet close to the axle, that might help. You can also put the magnet ON the axle sometimes.

However be aware that magnet orientation affects if the reed switch triggers.  And also how the magnet is polarized, that is some magnets are polaized so the N & S ends are at the physical ends of the bar or shape and "flat" thin surface is wweak magnetism.  Other magnets are polarized so the "flat" faces are the strong N&S while ends are weak magnetism.

There are some really tiny magnets available that work perfectly for this task.

Check K&J Magnetics Disks out.

I use magnets that are 1.5mm in diameter. Install closer to the axle.

Bill

Thanks guys.I pulled it off and re glued it just a hair off the axle.I have had it running for 45 min.Still chuffing.Thanx.Nick