Hey Everyone,

Im making an RJ45 cable tester to check that its been wired up correctly. I'm using a 555 timer and a 4017 counter circuit with rj cable connected across the counter outputs with LED's. If the LED's light up in order then they are fine. I was looking at trying to add a buzzer if it goes wrong and possible sequence checker. Wonder if anyone had any suggestion on best way to do this???

 

An exclusive OR gate from a wire input to output would detect errors on your set-up.

You then combine the outputs (probably an OR gate) to drive the buzzer.

 

If the LED's light up in order then they are fine.

The little commercial RJ45 tester I have has 2 pin bi-color LEDs to detect interchanged wires in a pair. Green=OK, Red=Backwards. I don't know if its a doable addition for your circuit but thought I'd throw it out there.