LED powered by parellel port?

[Paul]

Just wanted to know if I could safely connect a 12 volt LED to the voltage
out of the parellel port on my PC? I need to place a constant load on the
parellel port so my PC will think that something is plugged into it. The
parellel port device that I have plugged in stops working after a few
minutes. It's USB powered and not by the parellel port so I think the PC
shuts the parellel port off thinking nothing is plugged in. Thanks in
advance.

 

[JRW68]

I am by no far an expert at parallel ports but I have been researching
it and trying to learn about them. From what I have read the
parallel port only outputs 5Vs at 6mA..... my point is .. maybe a
smaller LED with an inline resistor (4.7kohm)? Ive read that you can
overload the parallel port circuit easily by overloading it.

I dont know if that helps at all, most of that information pertains to
the outputs of the parallel port. I am not familar with a 12v supply
coming out of the P.P. unless the 12v diode will work at alot less
voltage.

I bet you already knew that.... just thought I would throw it out
there.

Seems like your quite abit more knowledgable than me with respect to
P.P. and USB uses.... any suggestions on where I might find some
info, good book, one miracle site that ive missed?

 

[Paul]

I am by no far an expert at parallel ports but I have been researching
it and trying to learn about them. From what I have read the
parallel port only outputs 5Vs at 6mA..... my point is .. maybe a
smaller LED with an inline resistor (4.7kohm)? Ive read that you can
overload the parallel port circuit easily by overloading it.

I dont know if that helps at all, most of that information pertains to
the outputs of the parallel port. I am not familar with a 12v supply
coming out of the P.P. unless the 12v diode will work at alot less
voltage.

I bet you already knew that.... just thought I would throw it out
there.

Seems like your quite abit more knowledgable than me with respect to
P.P. and USB uses.... any suggestions on where I might find some
info, good book, one miracle site that ive missed?

I would try forums instead of news groups. Forums seemed to attract more
folks with knowlege than news groups do. I posted here because I was too
lazy to do a google search for a decent electronics forum. I'm not sure
what the voltage is from a PP but I know that a USB is 5V. I thought that
the PP was 12 but I could be wrong.

 

[scada]

Just wanted to know if I could safely connect a 12 volt LED to the voltage
out of the parellel port on my PC? I need to place a constant load on the
parellel port so my PC will think that something is plugged into it. The
parellel port device that I have plugged in stops working after a few
minutes. It's USB powered and not by the parellel port so I think the PC
shuts the parellel port off thinking nothing is plugged in. Thanks in
advance.

The input/output (IO)of the parallel port is 5V logic. If the PC program is
actually polling the port for activity, it probably won't be in the form of
a load. It would likely send some information, then expect a reply back! The
possibilities are many. Your best bet would be to get a port monitor program
(do a google search, you will find free ones!) and monitor what your device
is seeing! Or buy a port monitor, which is a device that plugs between the
parallel port and the hardware. It has LEDs on each pin, to monitor the
status.