HI David,

DD> I wish to make an electronic device for simple testing of thin
DD> ethernet cable.
DD> I want it to have two LEDs, one red, one green.
DD> I want to plug it onto a hunk of 50 ohm thin ethernet cable and have
DD> the following happen:
DD> If the resistance (impedance) of the cable is somewhere near 50 ohms,
DD> the green  LED would light;
DD> If the resistance/impedance is significantly less than 50ohms
DD> (a short?), the red LED would light;
DD> and if the resistance/impedance of the cable was significantly greater
DD> than 50 ohms (open circuit?) no LEDs would light.
DD> I want to be able to plug this onto the end of a cable and walk around
DD> wriggling connections trying to find the dicky one.
DD> At the moment I don't have enough hands to hold the two probes of a multi
DD> meter onto the BNC plug, and do the wriggling.
DD> Any circuit suggestions?

Yeah, get a time-domain reflection meter. There really is a "little" more
to Ethernet cables and faults therin, other than a straight 50-ohm
measurement. Actually there was a design in CC-Ink some time ago for
such a beastie.

Regards, Brenton
@EOT:

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