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SA9 and SA9-S



branchline with siding for alternate auto shuttle of trains

The SA9 is a single line shuttle with a siding at one end two allow two trains to run alternately along a single track line. There are versions of the SA9 to either control two signals at the siding end (SA9-S) or one siding at the single track end (SA9.1-S). The SA9-S gives a gradual adjustable braking and acceleration, an adjustable speed and adjustable wait time at the ends of the line. It has controls on the board to operate the point signals

The SA9-S operates as follows. Both trains always start at the left-hand sidings. The points change for the first train. There is a short delay. The signal clears (changes to green) for the first train. There is a further short delay. The first train accelerates away to the right. On being detected at D4 the first train starts slowing gradually and stops when detected at “D3”.  After an adjustable delay time the first train accelerates back to the left, braking on reaching D3 and stopping at D1.  After an adjustable delay the point changes for train 2.  There is a short delay and the second train’s signal clears. After another short delay train 2 accelerates to the right, braking upon reaching D4 and stopping at D3.  After the adjustable delay it accelerates back to the left, brakes at D3 and stops at D2.  Both trains are now back at the starting position and the sequence repeats from the beginning.


speed wait and acceleration are all controlled by the SA9 red and green LEDs fitted to the board show the operation reached

In addition to the SA9-S board you require 5 train detectors These tell the SA9 where the train is so that it can slow or stop the train. Either IRDOT-1s or reed switches may be used as train detectors. Reed switches require magnets be fitted to the engine or rolling stock. You also require a power supply of 12 to 16volts and a source of power for the point motors

The train detectors are indicated by a red X. They are numbered D1, D2, D3, D4, and D3. These numbers refer to the terminals on the SA9-S board to which the detectors are wired (note two train detectors are wired into terminal D3 on the SA9-S). D3 (in the centre) and D4 make the SA9-S start slowing the train. D1 D2 and D3 (on the single track end) make the SA9-S stop the train. They all work in a sequence ie if the SA9-S has not been told to slow the train it will ignore the stop detector. If you intend your trains to run slowly and do not require braking or acceleration you can achieve a similar set up using the Simple Shuttle and two IRDOT-Ps. There must be a distance of more than a train length between the two slowing detectors D3 and D4 for the unit to work correctly. If the distance is less than this use one of the SA9 (4detector). These are described later.

Point operation

A solenoid point motor is wired to terminals on the SA9 which close momentarily

The SA9-S operates solenoid point motors such as Peco, Seep and Hornby. There are two sets of contacts on the SA9-S board. These contacts close for a second to operate the point. The wiring is virtually identical to wiring a point motor operated by a momentary switch. If requested, versions of the boards suitable for a slow motion point motor or a servo motor can be supplied.

Signal operation

The SA9-S operates two colour light signals

Signal operation uses contacts on the SA9-S board, allowing any type of two aspect colour light signal to be operated. These ontacts shown in white have no electrical connection to the SA9-S board.

Semaphore signals can also be operated. Some options to operateare:- Use the contacts to switch the dual servo motor controller and use a servo motor to control the semaphore signals movement. Operate the semaphore signal by memory wire, using the closure of the contacts to apply current to the memory wire.Use a slow motion point motor wired via the contacts with an AC supply and diodes to give a change in DC polarity to the point motor. See the circuit for Kato point motors.

Adjustment Controls

No controller is required. The following adjustments are provided:- maximum speed, minimum speed, acceleration/braking, waiting time. Each adjustment is made with a pot fitted on the SA9-S board. The pots are adjusted by rotating with a small screwdriver. Maximum speed: The train accelerates until it reaches the maximum speed set. It then continues at this speed setting until it starts braking. It starts braking when it is detected by D3 orD4 (depending upon the direction the train is travelling).Minimum speed: On being detected at D3 or D4 (depending upon the direction the train is travelling) the train brakes to the minimum speed. The minimum speed is adjusted so that the train travels very slowly until it reaches the stop detector (ie D1 or D2 or D3).The purpose of the minimum speed is to ensure the train will stop in the desired place preventing the potential problem of the train stopping before it reaches the end of the platform. Acceleration/braking: This allows the train to gradually increase or decrease speed in a realistic way. It is adjusted by rotating the pot. The pot adjusts the rate of braking and of acceleration. Turned one way the train accelerates and brakes more slowly. Turned the other way the train accelerates and brakes more quickly.

Waiting time: This is the time the train waits at each end before returning. The waiting time can be adjusted between 10 and 150 seconds.

Current rating: All boards are fitted with an overload cutout. This operates at 1 amp. Units can be modified to supply a higher current for use with G scale etc. We are happy to quote for this modification.

Power Supply: The SA9-S can be powered from any supply between 12 and 16 volts, either AC or DC. Generally the majority of the current goes to powering the engine. If you do not already possess a suitable power supply our 12volt DC 1.25 amp supply is very suitable.

Operation: The SA9-S gives a DC output to the track. If the track controlled by the SA9-S connects to the rest of your layout you will need isolation breaks between the SA9-S operated section and the rest of the layout. The diagram shows how to wire a DPDT (double pole, double throw) toggle switch (shown in yellow) so that you can have a choice of manual or automatic operation on the SA9 track. The controller may be either DC or DCC. Although the output from the SA9-S is DC, DCC decoders operate with either DC or DCC in dual mode. Normally they are factory set to dual mode. Dual mode is easily set by with the CV 29 value. If it is not already set add 4 to the CV value.

Dimensions Length 93mm Width 93mm Height 43mm

SA9 Single line shuttle with siding at one end Exactly as described for the SA9-S but without the signal operation. SA9.1-S Single line shuttle with siding at one end and control for one signal As described for the SA9-S but with only 1 signal which is positioned at the single track (right) end. This unit could be used where the siding end is hidden and the single track end is visible. The effect is given of 2 different trains arriving alternately at a terminus station.

SA9 short, SA9-S short and SA9.1-S short If the line is short (i.e. if the train could overlap both slow down detectors) then one detector located at the middle of the line can be used to start slowing trains traveling in both directions. Four train detectors are required. Otherwise the operation is identical to the standard version of the boards.

If you require extra sidings at one or both ends of the line then this is done by using IRDOT-Ps at each stopping position. The IRDOT-Ps perform two functions. They indicate to the SA9 when to stop the train and they change the points ready for the next train to depart.