BeebMaster - I Want an Econet! - Build your own Econet


Build your own Econet


Creating the Network

It is best to have an idea in mind of the layout of your network, ie. where you want your workstations and socket boxes. These can be changed or added to later but it may require a lot of extra work if you have to start ripping socket boxes off the wall or tearing out wires.

The first thing to do is to connect the network itself together. This is done either by connecting the T-pieces together, wiring the socket boxes together or a combination of the two.

Using T-pieces

The advantage to using T-pieces is that they don't require any network cable, fiddly stripping down of wires and so on and the whole network can be totally reconfigured at will simply by disconnecting everything and putting it back together again. The disadvantage is that they can be difficult to find and you will need a lot more Econet leads for your network.

You will need to work on the following ratio:

1 T-piece per Beeb plus two for the clock
1 Econet lead per Beeb plus two for the clock plus 1 for every T-piece less one.

Let's assume we are going to create a network of three BBC Micros. Using the above calculation, we will need the following:

5 T-pieces (1 per Beeb = 3 + 2 for the Clock)
9 Econet leads (1 per Beeb = 3 + 2 for the Clock + 1 per T-piece less 1 = 4)

First, form the network by connecting the two-socket ends of each T-piece together using the Econet leads. This will leave a spare socket at each end of the network for the terminators.

Then connect further Econet leads to the one-socket end of each of the T-pieces. These will be connected to your Econet workstations and clock.

There is an illustrated guide to connecting up T-pieces here.


Using Socket Boxes

Both Acorn and SJ Research produced socket boxes and terminator boxes for Econet.

The advantage to using socket boxes is that they provide a more permanent Econet installation and you can regulate the distance between socket boxes by using different lengths of network cable to suit your own needs.

The disadvantage is that you will need a supply of network cable as well as Econet leads, there is some fiddly wiring work inside the boxes and it can involve a lot of extra destruction and reconstruction to expand a network.

The socket box lids are removed revealing sets of blade connectors for pressing in the network cable. With Acorn socket boxes, the network cable insulation must be stripped away at each socket box and the wires inside pressed onto the blade connectors with a cable insertion tool.

There is a bit more versatility inside the SJ Research Boxes as they each have two sets of blade connectors. You can either strip away the insulation and use the middle set or cut the cable right through and attach one end to the left-most set of blade connectors and the other end to the right-most set. This is not recommended by Acorn or SJ Research but if you are as hopeless at wiring as I am, it may be the only option.

There is an illustrated guide to Acorn Socket Boxes and how to wire them up here.

There is an illustrated guide to SJ Research Socket Boxes and how to wire them up here.


Combining T-pieces and Socket Boxes

It is not difficult to see how you could use a mixture of socket boxes and T-pieces on an Econet. I have used such a system on the branch line of my own Econet which serves Stations 200 and 201.

From the last socket box in the chain, either solder a 5-pin DIN plug to the wire coming from the box, or use a cut-off Econet lead attached to one set of blade connectors inside an SJ Research box. Attach a T-piece to the Econet DIN plug and continue to the form the network with T-pieces.

If you are going to use part of an existing Econet lead, be very careful that you connect up the pins correctly. The diagram below shows the correct pinouts on an Econet lead VIEWED LOOKING INTO THE PLUG. Of course you will need to work out for yourself which colour relates to which pin.

1 Clock +
2 Earth
3 Data +
4 Clock -
5 Data -