Re: First note-Help

Hi,

The best guess that I have is the circuit inside the US Digital or
HP's HEDS encoders is some type of hybrid circuit that does not avail
itself of a "large" component like a .!uF cap. It does kind of boggle
the mind that it would be left out where it is so obviously required.
In my case it is a surface mount 0805 part, meaning it is .08"
by .05" by .03" in height and costs a mighty 8 cents/per unit. Not
exactly large by anyone's measure.

I measured the +5VDC to GND pins on several modular encoders I have
with a capacitance meter and they all showed less than 100pF. This is
a really suprising result to me. I would have expected a reasonable
bypass capacitance.

The net result is if you are going to use these encoders you MUST
supply your own bypass at the encoder power inputs for them to be
usable devices. Why the mfgs. didn't do so or indicate the need for
bypassing in their literature perplexes me.

Mariss

--- In CAD_CAM_EDM_DRO@y..., JanRwl@A... wrote:
> In a message dated 29-Jun-01 16:06:53 Central Daylight Time,
> mariss92705@y... writes:
>
>
> > The cure was to place a .1 uF multilayer ceramic capacitor across
the
> > encoder's +5VDC and GND lines, at the encoder itself. Problem
> > disappeared entirely!
> >
>
> It always blows me away when a MANUFACTURING FIRM doing "high-tech"
will omit
> some TINY inexpensive parts so OBVIOUSLY needed for such! Mariss,
or anyone:
> Can you comment instructively on this point???
>
>
>
> [Non-text portions of this message have been removed]