voltage at pins

Nov 18, 2004 3 Replies

Rate this thread:

H. BrÃ¼ggemann 21 years ago

Hi all,

I wanted to check traffic between two pc's. I have 100 megabit ethernet. I cut a original cable (cross over) and reconnected tx+ and rx+ tx- and rx- rx+ and tx+ rx- and tx-

The cable works fine. Between the open pins of the cable I put a LED incl. a resistor to "see" the bits. But there is no light during traffic. I used a LED where I can see the light from 1 milliampere. So I thougt the load is low enought. I expected a voltage between the pins lower than 12 volt. Thats why the led got a 4 kiloohm resistor. The traffic is not disturbed by the LED.

Any suggestions?

Helge

Vote

T. Sean Weintz 21 years ago

LOL. MUCH lower voltage than 12V. Less than the voltage needed to drive most LEDS. Spec is I belive between 2.2V and 2.8V. Your gonna need to use an op-amp or sumpthin in there to drive your LED.

Vote

T. Sean Weintz 21 years ago

HEHEHEHE...

He didn't specify he wanted the LED to be off when there was no traffic, only that he wanted it ON when there was traffic....

Easiest solution of coruse would be to stick a cheap switch or hub inline on the cable.

Vote

Manfred Kwiatkowski 21 years ago

Even better. If he succeeded to drive his LED it would shine all the time as there is a constant flow of symbols and I doubt the LED will interpret an IDLE. :-)

Vote