Where can I find technical information about Tachogenerators?

Question

I want to find tehcnical information in how does tachogeneratos works, but most of the searches in the web lead to manufactures who only give info about their products, but not the physical principle in the functioning of these machines. Do you any website were i can find pshysical information about tachogenerators?

Answer 1

Tachogenerator, or tachometer, seems to cover a range of mechanisms. The most common are permanent magnet DC generators and drag cup AC generators, shaft coupled to the rotating device to be measured, digital tachs, also shaft-coupled, and pulse generators, which are not directly connected but use an induction coil to detect passage of a magnet attached to the rotating device (much like a bicycle speedometer) or a photocell to detect light interruption by a passing vane, producing a pulse rate proportional to speed.
See the refs. for a couple of possibly useful pages.