help needed on dc motor

hello people...

i learnt that the dc motor has a loop that rotates around two fixed magnets creating an emf. this emf is an alternating one.. so if i place a load across the loop, then AC current flows thru it...

the commuttator converts this ac voltage to dc voltage and this dc voltage appears across the brushes...

is there any way by which i can record this alternating voltage directly??? i am not interested in the dc output of the motor and want to see the ac voltage produced in the coil... can u please help out???

thank u....

You need an alternator, and NOT a dynamo - instead of brushes and a commutator you have slip rings. Or, even more simple, if using a permanent magnet, you spin the magnet and keep the coils static.

do we get small alternators? becuase i googled alternators... and i could find many of them explaining about car alternators which are very huge and costly...

do we get alternators reasonably priced like a dc motor?

also... if i turn the rotor of a DC motor using an external geared shaft, will the output voltage be AC or DC???

A DC motor will obviously produce DC.

You might try a stepper motor, which is an AC 'motor', not a DC one.

There are small 'alternator' avalible in the Radio Control hobby. These are brushless DC motors where the motor controller generates the 3 phase voltage for the motor. They have magnet rotor and 3 phase windings. Come in many sizes and start out pretty affordable for the smallest sizes.

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Lefty

Modern bicycle dynamos are really alternators and are quite cheap, you're best bet is to visit your local bike shop.