Re: Stepper motor as an encoder

Bob,

Nice circuit but it still doesn't get around the problem. The circuit
has a miniscule amount of hysterisis to latch the output to the last
signal peak, + or - . It would work down to 1/3 RPM as stated as long
as the detent torque is unloaded. The detent torque causes momentary
velocity to generate a voltage on the coils. A real world load would
swamp out this effect, rendering it useless at speeds below 1/2 RPS.
It also cannot address sensitivity to vibration (microphonics) at
these very low speeds.

To qoute from the listed page, note the honest caveat:

"The problem with a stepper (or any other motor) used as a generator
is that at very slow speeds it gives virtually no output - so there
is a problem with slow speeds. You have to make some sort of trade
off between high speed and low speed performance. Proper encoders use
optical switches which work at any speed."



Mariss

--- In CAD_CAM_EDM_DRO@y..., "cncdxf" <cncdxf@a...> wrote:
> Hi,
> The link below sums it up.
>
>
> http://www.4qdtec.com/stpen.html
>
>
> Bob