[Tibbs]

Why do some motors have a ferrite man and some don't and what does he do?

Thanks

[Scuderia_Turini]

Hello Tony,
The "Ferrite Man" evolved from the old fashioned radio interference suppressors fitted to Scalextric cars in the early days. The combined effect of the bead capacitor and ferrite core is to reduce the electrical noise produced by the motor being transmitted both through the air and also back down the rails and to the power source. The noise originates from the arcing of the brushes as the commutator rotates past them.

In the early days the suppressor was present to avoid interference with radio and television apparatus, much in the same way that car ignition systems used to need suppressors on the spark-plugs and distributor contacts if a radio was fitted. Technological advances meant that tv and radio became less susceptible and the suppressors on slot-cars became almost redundant.
In the Digital era, suppressors became crucial to avoid corruption of the data signals that are fed through the power rails hence the suppressors fitted at the guide/pickup.
For analogue running the suppression is not really essential, unless your television or radio gets crackles. Although in some situations the suppression may be necessary to avoid false triggering of lap timing sensors.

Leo

[Tibbs]

Thank you Leo, really appreciate it.
Every days a school day 

[Gpa113]

Excellent information Leo.
So easy to understand when it is presented so clearly.

[Fluff]

Some of the early information films (  1950 ) showed a car unsuppressed blowing up a householders tv set  

Steve

[MrFlippant]

Sounds more like a scare tactic so that people don't remove them and annoy the neighbors trying to listen to the wireless. ;-)

The big secret is that they do NOT effect the power the motor gets. Analog racers, to this day, remove those in the mistaken impression that they'll gain any kind of voltage or power by doing so. Fortunately, removing them doesn't hurt anything these days.

As Leo pointed out, though, if it's a digital car, you'd be well advised to leave them on both the guide and motor, but especially the motor. Some systems even need extra ones added.