I have a DC motor and the sticker says its rated for 24Vdc and 3700rpm.
There is an AC tacho inside it which I am using to measure the speed of the motor.
So when I run the motor with a 24Vdc supply and measure the AC tacho output I get a frequency of around 900Hz. So I am correct in assuming there is a gearbox inside the motor that is speeding the tacho up?
And if so, is it accurate enough to calculate the gearbox ratio based on the motor speed and AC tacho frequency? I want to use it to calculate the motor speed?
Would appreciate any help, thanks everyone.!
See image of oscilloscope with motor running full speed and no load