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

Matthew King wrote:

> 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 means that the chip sends current out the pin. Sink means that current
flows into the pin. Current, in the electronics industry is backwards because
Ben Franklin had to guess at the polarity of the charge carrier, and he guessed

wrong. So, electron flow is from negative to positive, but we talk of current
flow
from positive to negative.

So, in a source situation, the chip would send current out through a resistance

to ground. When sinking, it would draw current through a load from the
positive
power supply. (All this can be different in logic that runs from negative
power
supplies, but most stuff use positive.)

Jon