You also mentioned 30 or so feet of wire. That's likely also an issue with
respect to electrical noise pounding away at the PC driver pin and eventually
causing the output circuit to fail.
Although I only made a few of these boards and never did use the one on this
web page the general idea is
On Wed, 22 Feb 2023 at 16:30, Todd Zuercher wrote:
>
> Do different parallel port output pins have different current sourcing
> capabilities?
Yes, and also they may have different current limits in EPP mode.
In general P-port pins can sink more current than they can source
(generally 15mA, ple
Damage from over-current is cumulative. The bond wires that go from the
chip to the lead frame are VERY thin and will heat up and can only do this
for so many cycles.
What you might try, to protect the other pins, is to use a higher value
current limiting resistor on the LEDs
On Wed, Feb 22, 2
I have an older Linuxcnc installation that uses a parallel port. It has 4
TCRT5000 optical sensors, that I was powering the IR LED with an output from
the parallel port (and reading the IR sensor with an input.) It had been
working fine for some time, but I only use this equipment once a year.
