Re: [CAD_CAM_EDM_DRO] Parallel Port/Relay Problems... more

> Ok - I'm not an electronics type by any stretch, but I *am* trying to learn.
> I've heard the SOURCE/SINK reference many times. Could someone please
> explain this nice and simple-like? Sorry for the doltish question, just
> trying to understand....

Source is the amount of current which the output can 'push' when it is
positive, sink is the amount it can 'pull in' when it is negative or
near ground. For certain types of devices, the numbers can be vastly
different. (For some devices, the number in one direction is zero)

The terms are conventional... physicists later pointed out that
current consists of electrons, which are negatively charged, and
actually flow the other direction, from negative to positive. So
people talk about, and arrows on schematic signals remain in terms of,
a ficticious 'conventional current' which flows from positive to
negative.

Chris

>
> Thanks,
>
> Matt
>
>
> -----Original Message-----
> From: Alan Marconett KM6VV <KM6VV@...>
> To: CAD_CAM_EDM_DRO@yahoogroups.com <CAD_CAM_EDM_DRO@yahoogroups.com>
> Date: Wednesday, December 05, 2001 12:51 AM
> Subject: Re: [CAD_CAM_EDM_DRO] Parallel Port/Relay Problems... more
>
>
> >Hi Chris,
> >
> >I must have missed the original question. Are you trying to control a
> >solid state relay, or a relay from a pin on a parallel port? And your
> >software has an Mcode to use? If you'll afford me a guess, do you have
> >a 1K pullup to +5v on the pin? and are you trying to SINK current, not
> >SOURCE it? a 220 ohm resistor connected to +5 and in series with an LED
> >makes a good test probe. You should see the respective pin control the
> >LED of all is working.
> >
> >This will allow you to divide the problem in two! Makes it easier to
> >debug.
> >
> >HTH
> >
> >Alan KM6VV
> >
> >
> >Chris Clough wrote:
> >>
> >> Ok - so I went and got all new components and rebuilt it twice now today
> >> - I'm using the schematic of off Tim's site - I built it, had two EE's
> >> look at it, and said that's the way it is on the page so... what's my
> >> next option?
> >> Any help - PLEASE :(
> >> -Chris Clough
> >> Xtech Engineering
> >
> >
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