INSTRUCTIONS FOR THE SA-2 AND SA2-S
Apart from the operation of signals these instructions apply to both the SA2 and SA2-S.
The SA-2 operating sequence is as follows:
Both trains always must start at the left hand sidings. Points change for train A. Short delay. Signal clears for train A. Short delay. Train A accelerates away to siding at right. Adjustable Delay. Points set for train B. Short delay. Signal clears. Short delay. Train B travels to right hand end of line. Both trains are now at right hand end of line. Adjustable delay. Points change for train A. Short delay. Train A travels back to starting position at left. Adjustable delay. Points change for train A. Short delay. Train B travels back to starting position at left. Both trains are now back at the starting position and the sequence continues.
Powering the SA2
A 5 way terminal block is used to enable the power for the track to be split from the power to the SA2 control electronics. This is useful if it is required to combine the SA2 with a controller.
Everything powered from 12 volt DC supply
This is the simplest way to use the unit. Add a wire link and connect the 12 volts D.C as shown below. The wire link connects the 12 volt dc supply to both power the SA2 and to power the track. (the SA2 reduces the voltage on the track).
POWERING FROM AN AC SUPPLY
The unit needs a diode and capacitor fitted as shown below. Note the band on the diode and - sign on the capacitor which show which way around to fit the components. The unit is usually supplied with these 2 components fitted.
TRAIN CONTROLLER
Either a 12 volt DC supply or a 16 volt AC supply is connected as shown previously to power the control electronics and the IRDOT-1s. The wire link is removed. The controller is connected as shown, all other wiring is identical to the 12 volt DC supply diagram. In effect the controller now sets the maximum speed. The SA2 acceleration and braking still operate.
TRAIN DETECTORS
Either IRDOT-1 or reed switch train detectors can be used. Six train detectors are required. The positions of the train detectors are:
X marks the position of the train detector, the symbols (such as D3) refer to the SA2 terminal which that particular train detector must be joined to. Train detectors D1 stop train A. Train detectors D2 stop train B. D4 (start of) braking for left to right trains. D3 (start of) braking for right to left trains. Both "braking" train detectors should be positioned to give approximately the same distance to the stopping position.
The diagram below shows the wiring of the power supply to the SA2 control electronics and IRDOT-1s. Terminal "6" of the IRDOT-1 and terminal o of the SA2 are connected to the negative (or 0 Volts) connection of the power supply. Terminal "1" of the IRDOT-1 and terminal "+" of the SA-2 all connect to the positive (or 12 volts) connection of the power supply. Alternatively all the units can be powered from a 16 volts AC supply. If an A.C. supply is used be careful to ensure the units are connected as described above otherwise the train detectors will not be able to operate the SA2 although they will still detect trains.
The next step is to wire the train detectors to the correct inputs (D1 to D4 as shown above). If the IRDOT-1s are used wire terminal 2 to the appropriate input. Some of the terminals have two train detectors connected to them.
If reed switches are used wire one end of all the reed switches to the o (0 volts) terminal and the other end of the reed switch to the appropriate terminal of the SA2. (D1 to D4.)
INSTALLATION OF POINT MOTORS
The SA2 has two relays for switching the point motors. The relays momentarily switch on for approx 1 second to operate the point motors. PECO or SEEP point motors are suitable. Both points are switched together the wiring is shown below.
To check the wiring is correct ensure that on powering the SA2 both points switch to the D1 sidings after the initial delay time. It is preferable to use a separate power supply for the points to avoid electrical interference problems. A capacitor discharge unit can be used.
WIRING THE SIGNALS (SA2-S ONLY)
Relays on the SA board switch the signals. These contacts are not electrically connected to the rest of the SA board. Wiring a signal to the SA board is identical to wiring to a change over switch.
The signals can use the same power as the SA4-S or a separate supply. The diagram shows wiring common positive LED signals using the SA4-S supply. The diode is only required if an AC supply is used. A resistor (usually supplied with the signal) is used with each signal to limit the current through the LEDs. Bulb signals can also be used.
The internal relay contacts are shown as thick lines. "sc" is the common to which one wire of the signals power connects. This is switched to one of the adjacent terminals by the SA4-S to light either the red or green. To give a realistic effect there is a short pause between the points changing and the signal changing to green then another delay before the train moves away.
Diagram on left shows common negative signals powered from a separate supply. Diode is only necessary if the supply is AC.
Diagram on right shows bulb signals. Use of resitors depends on voltage of bulbs and voltage of power supply.
Two relays are provided for switching signals at the left hand end of the line. The signals are normally at danger clearing a short time before the trains are due to depart. The signals can either be powered from the same supply used for the SA2 or a separate supply.
SEMAPHORE SIGNALS
The relay can be used to operate semaphore signals by using it to operate a slow motion point motor or a relay the arm of which has been adapted to move the signal.
TESTING AND SET UP ADJUSTMENTS
This is best carried out in the following order.
Turn the variable resistors with a fine screwdriver to give delay time=short, min speed=slow, max speed=fast, ACC/BR (rate of braking/acceleration)=abrupt.
Position the trains at the left hand end of the line. After the variable delay (green and red flashing) the points will switch to the D1 sidings and there will be a short delay with the red LED lit. The signal will switch to clear followed by another short delay. The green LED will light (indicating acceleration) and the train (on the D1 siding) will quickly accelerate to maximum speed. If it travels in the wrong direction reverse the track power connections out of the SA2. When the train is detected by the train detector connected to the D4 terminal it will rapidly reduce speed and halt (the red LED will light indicating braking). Adjust the min speed setting until the train just moves . It will then travel to D1 and stop. After the delay time the points will change and the train on the D2 siding will move, on reaching D4 this train will brake (a further adjustment to the minimum speed setting may be required due to possibly different electrical characteristics of each locomotives motor). As the sequence continues adjust the maximum speed setting to the required speed (unless using the controller to determine the max speed,in which case the maximum speed should be left at max). As successive trains brake (indicated by red LED only lit) adjust the acc/br setting so that the train slows to the minimum speed just before reaching the appropriate train detector.
Note: min and max speed adjustments are confusing to set unless acc/brake is set to abrupt because of the effect of electronic inertia. Also maximum speed can only take effect whilst the green LED is lit and Minimum speed only whilst the red LED is lit.Finally adjust the delay time setting to the desired time. Note that the length of the flashes is proportional to the delay time.
Overload protection
Overload protection is built into the SA2 and SA2-S. If an excessive current is drawn from the unit then the overload circuit will prevent the unit from being damaged by switching off power to the track. This fault condition is indicated by the red and green LED's both lighting. As soon as the fault is rectified the unit will resume normal working.
HEATHCOTE ELECTRONICS, 1 HAYDOCK CLOSE, CHEADLE, STAFFS, ST10 1UE
TEL/FAX 01538 756800 email
web site http:Heathcote-electronics.co.uk
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