Sound Synchronisation


Contact Free sound synchronisation with our new synchronising disc

Key Features

  • Non contact

  • No wheel disassembly

  • No contamination with dirt

  • Easy to set up

Developed originally by Otto Shoustra for use with his unique sound systems EDM Models have with his permission developed the design for easier production and have made it available for a growing number of axle sizes.

  Sizes Available
Synch Disc for 2mm Axles £10.00  
Synch Disc for 2.5mm Axles £10.00  
Synch Disc for 3mm Axles £10.00 Suits Bachmann 0n30 loco's
Synch Disc for 3.3mm Axles £10.00 Suits Romford/Markits 1/8" axles
Synch Disc for 4mm Axles £10.00 Suits MMI K class loco's
Replacement Reed Switch  7mm Long   no longer stocked  
Replacement Reed Switch  5mm Long £1.00 each
Replacement Magnets £5.00 pack of 4

Please Note -

  • Originally these items were laser cut in brass. As stocks run out they will be replaced by laser cut plastic as we can do that in house now

  • If you need a different axle size then please ask. Now we can do the cutting ourselves a new size can be available in about 2 weeks from request

  What You Get
  • Clever Disk Fret
  • Reed Switch
  • Special Magnets


  How it Works
Well, I'm certainly not going to tell you all its secrets but here is a summary.

The four sections of the "clever disk" assemble around the axle without removing a wheel and are clamped in place by the two assembly wires. The special magnets then glue into the recesses in the disk. This whole assembly then rotates with the axle, but at this stage can be moved in the axle. The reed switch is an enclosed set of contact that responds to the magnets and close four times a revolution. This switch is wired to the sound circuit of your loco.

  Installation Instructions

Congratulations on you purchase of an OSSYNTHS contact free sound synchronising disc. The Ossynths sync disk was designed by Otto Schouwstra for use with his own sound system and is now manufactured and marketed by EDM Models.

  1. Tools required

o         Small files

o         Taper broaches

o         Wet & Dry paper

o         Cyanoacrylate glue

o         Multi-meter or Test lamp

o         Solder & Soldering iron

  1. Prepare the disc components.

The fret is cut with a laser which can leave some slightly rough edges and a little bit of preparation is needed. Ease the four layers of the disk from the brass fret. Clean the tabs off with a fine file and then rub the flat faces on some fine wet and dry paper to ensure all the burrs are removed.. Check the slot will slide easily over your axle. It should be a close fit, not loose, but not needing to be forced either. Ease with a fine file if needed. Make sure the wire for the pins fits through the holes.

  1. Assemble the disc to the axle

The disc layers are assembled on to the axle alternating sides and then easing the pins through the holes as shown in the sketches. Once happy with the placement of the disc the layers can be secured to each other and to the axle with a small drop of cyanoacrylate glue. Only the smallest drop is needed as the disc is under no stress.

  1. Understanding the magnets

How the magnets are arranged is critical to the working of the OSSYNTHS sync disk. The magnets have two poles, north & south, when new the north pole is marked with some red dye. If the dye is missing its not a big problem, what we need to know is the difference between the poles. Try this; lay the magnets in a straight line, if two adjacent magnets stick to each other you have a north and south pair. If they repulse each other you have either a pair of north's or a pair of south's

 [Tip1 – stick them in a row, mark the right hand end with a marker pen, pull one off and mark the next, repeat. Now you have all the same poles marked]

The four magnets are glued into the semi circular indentations in the assembled disc. They should be arranged as shown in the sketches so that there are alternating north and south poles around the disc.

  1. Locating the reed switch

The reed switch supplied in the kit goes in the positions 1a or 1b shown in figs 1 & 2. This is either at 90 degrees to the axle or parallel to it.

[Note: When bending the wires on the reed support the wires adjacent to the glass with pliers to prevent the glass being broken]

The range over which the reed will sense the magnets will be in the range 1 – 6mm but you will need to test the set up to find the optimum distance as it will be affected by the proximity of other bits of your model. It might seem obvious but mount the reed away from the motor – it’s a big magnet!

Solder two fine wires to the reed switch and connect these to a test lamp and battery or to a multi-meter on the “beepsetting. First test the reed switch by moving a magnet close to it. Once you know your test circuit is working move the reed into the position you want to mount it on your engine. Rotate the axle and check that you get four clear beeps per revolution. Move the reed nearer to, or further away from the magnets until you get clear pulses.

Once you are happy with the location permanently mount the reed switch in that location fabricating any small brackets you may need. Typically we use bits of copper clad ties or bits of styrene.

  1. Connecting up your Synch Disc

How you connect your OSSYNTHS sync disc to your sound system will vary from system to system. For use with Soundtraxx digital sound decoders connect one end of the reed to the tan wire of the decoder and the other end to one of the models power pickups.

  Other Permutations
More Axle Sizes

3/16"  coming soon  

tell us what others you want


Chuffs for Shays -

Want 8 chuffs? Mount two reed switches 1/8 of a turn apart and wire them in parallel

Want 12 chuffs? Mount three reed switches 1/12 of a turn apart and wire them in parallel


[I confess - so far I haven't tried this.]