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Step 7 : How it works
The design is simple and allows testing of all three cable types, and the configuration is Master and Slave, so that you can test your runs of cables easily.
The heart of the Master unit is a 4060 14 bit ripple counter and a 3:8 Demux 4051.
the 4060 includes a simple RC oscillator to drive the ripple counter, and this inturn is De-muxed by the 4051 to drive LEDs connected to the sockets and test cable.
the first four LEDs in the master provide indication of continuity and operation (there is no on/off switch).
The cathodes of each of the LEDs is connected to the Rj-45. this provides a positive source current to test the cable and drive the slave unit.
The slave unit consists of a current limiting resitor (1.5k) and a Red and Green LED wired in reverse parallel. This configuration will provide a green light, if the cable pair is terminated corectly, and a Red light if there is a reversal.
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