Re: stepper problem

hi,

Here's how it could do that. The direction line is high (+5VDC).
Current flows thru the direction 200 ohm I limit, around the
direction LED 1K paralled resistor, thru the step LED and back to
ground at the PC. This means the step opto is unusually sensitive;
3mA probably.

Mariss

--- In CAD_CAM_EDM_DRO@y..., Jon Elson <elson@p...> wrote:
> andrewyslee wrote:
>
> >
> > Ah!!! looks that there's still plenty learning to do!!!
> >
> > The old geeeezer found the problem. Amazing what a USD10
multimeter
> > can do!!! The +5V cable insulation had not been trimmed off
leaving
> > the connection open. Trimming the insulation off got the motors
> > humming along beautifully. But it means that leave us to puzzle
over
> > how without the +5V the Geckos can produce 1 way motion
(plus "soft
> > tingling noise") in the first place???
>
> Capacitive coupling, I guess. There was enough capacitance so that
very short
> pulses, maybe under 100 nS could make it through the opto-LEDs
until the other
> side charged up.
>
> Jon