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In networks, the supremacy of coax cable is a thing of the past. Nowadays, Ethernet connections are made using UTP cables. The BNC plug has yielded to the 8-way RJ45 plug. Previously, coax cables were daisy-chained from computer to computer and terminated at the two ends using 50-_ resistors, but modern networks use central ‘socket boxes’ (switches and/or hubs) to interconnect everything. The connections between the hubs and the computers are made using patch cables having the same sequence of leads in the RJ45 connectors at each end. For making a direct connection between two computers without using a hub or switch, a ‘crossover cable’ is used. Such a cable has the leads cross-linked in order to allow the two computers to directly communicate with each other. If there are problems with the network, it can be handy to be able to directly interconnect twocomputers, or directly connect a computer to a cable or ADSL modem without using a hub or switch. A long crossover cable is not always...

Battery clips and holders The standard battery clip fits a 9V PP3 battery and many battery holders such as the 6 × AA cell holder shown. Battery holders are also available with wires attached, with pins for PCB mounting, or as a complete box with lid, switch and wires. Many small electronic projects use a 9V PP3 battery but if you wish to use the project for long periods a better choice is a battery holder with 6 AA cells. This has the same voltage but a much longer battery life and it will work out cheaper in the long run. Larger battery clips fit 9V PP9 batteries but these are rarely used now.  PCB terminal block Terminal block Photographs © Rapid Electronics Terminal blocks and PCB terminals Terminal blocks are usually supplied in 12-way lengths but they can be cut into smaller blocks with a sharp knife, large wire cutters or a junior hacksaw. They are sometimes called 'chocolate blocks' because of the way they can be easily cut to size. PCB mounting terminal blocks provide...