Stephen Wille Padnos wrote: > > Incidentally, you could make something that does a more direct > conversion to analog, but it's still iffy as to whether it would work > well. Just use a simple circuit to do quadrature edge detection, and > have that trigger a short duration one-shot. The one-shot goes into an > averaging filter and an amplifier that can invert the output depending > on direction (the quadrature circuit would need to have a DIR output pin > as well). The faster the pulses come in, the higher the output > voltage. It more or less uses the quadrature data as the PWM. > > The old ST Microelectronics L290 chip did this. It used two identical sections, one for + movement, one for -, and used a diff amp to get the difference between the two. That way, fast jitter between two positions came out to zero velocity. I believe the chip in the Fanuc controls did almost exactly the same thing.
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