Controlling Two or More Trains on the Same Line?

The planned layout has long sections allowing multiple trains per line. Which presents an interesting set of problems:

• How to create block control in T-gauge?
• How to individually control each train on the same line?
• How to supply power to each train?
• How to vary the power supply to each train for speed control and reversing?

T-gauge is just too small for DCC to be feasible. So...

A schematic of the proposed solution is pictured below.



Schematic of train control concept.

The concept solution is as follows:

• Divide the line into blocks, with overlaps.
• Electrically separate the rails of adjacent blocks.
• Fit train detection to each block and overlap.
• Use software and PC to monitor occupany of blocks.
• Assign in software a unique ID to each train.
• Use software to 'follow' a train as at occupies and clears each block.
• Provide one speed controller per train.
• Use pulse-width modulation (PWM) with H-bridge to generate a variable voltage in proportion to each speed controller.
• Use software and hardware to switch using relays the PWM power from block to block, tracking the movement of the relevant train.
• Isolate power to a block by switching off the relevant PWM power if the occupying train is detected at the overlap and the next block is occupied by another train.

The schematic above shows only two speed controllers per line, i.e. two independently controlled trains per line, but more can be added. The complexity of doing so involves adding additional relays per block section to switch the additional power supplies connected to each block.

Finally, for the concept to work, train detection must be able to detect all vehicles of a train are clear of a previous overlap. Thus 'presence' detection is insufficient; a continuous train detection system is required. How to achieve this in T-gauge will be the subject of a future post - but it can be done!