What's the function of capacitors in dynamos?

[ChrisToffer]

what is the function of the cap 104, why is it there? what's the function of this cap in the dynamo.. i know caps are used in motors for P.F correction, but what about the dynamos in toys??

 

[jim hardy]

probably to 'absorb'(or suppress) the electrical noise from sparking at the motor's brushes.
Observe it's been placed as close to the noise source as physically possible which is good practice.

 

[Baluncore]

I agree.
That looks more like a DC motor than a dynamo. The worm gear confirms it.
The 104 capacitor is 10 0000 pF = 100nF and is there to prevent radiation of RF noise from the sparking at the brushes.

 

[Neumeric]

Dynamo in the US is an outdated term that used to mean generator and/or alternator not sure which. I was wondering if dynamo might just be Aussie for motor in the US?

 

[jim hardy]

in 1890's it referred to a DC machine which of course can both generate and motor.

As late as 1963 Austin-Healey 3000 labelled its dashboard ammeter with word "Dynamo"
but here the term is quaint.

I once used a small motor like the one pictured and controlled it with a 555 IC. Need for bypass capacitor at motor was immediately obvious.