Econet Type 2 Clock/Terminator/Hub

My Type 2 Clock/Terminator/Hub is an updated design based on the SJ Research Type 2 Clock with the following differences:

• I've used HC rather than LS logic though LS will work just as well (do not use a mixture !)
• 8MHz crystal oscillator module rather than discrete crystal and inverters
• includes active Data line termination selectable by links (as in the Acorn Type 1 Clock)
• includes Clock pair termination selectable by links
• includes five hub sockets

Note: the unit is powered from +12V DC.

This unit can be all that you need to connect up an Econet network by providing the Clock, Termination and sockets for up to 5 Stations.  It can be extended using the second Clock output.

The clock rate is set by selecting a MARK and PERIOD each of which is the sum of all the enabled switches in the bank.  Acorn recommend a safe value for Period of 5µS and for Mark 1µS.

Note that if the same duration MARK and PERIOD switches are selected there is a timing issue which stops it working, the simple solution is to add an additional 0.125µS to the MARK.  This is fixed by the addition of R7/C8 on later boards, these can be quite easily added to V1.0 boards with a track cut if required.

The PCB fits neatly in a Hammond enclosure:

I also have a avaliable a Eurocard version of the Clock.

Schematic

• Econet Type 2 Clock/Terminator/Hub Schematic

Bill Of Materials

• Econet Type 2 Clock/Terminator/Hub BOM

Box Drilling

• Econet Type 2 Clock/Terminator/Hub Box Drilling

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