True2scale True2scale Train modeling components
The Signal Controller4 circuit board is a new design on the signal tower controller circuits. This controller can be used to control either common anode or common cathode signal towers from other manufacturers. Several of the older controller circuits described below are now available for half price
This circuit board controls two signal towers. Inputs and Outputs here are referred to as Green, Yellow, and Red, but they may also control rotational signal towers. The upper half of the circuit controls one signal, while the bottom half controls a second signal. The two halves share the power supply connections and isolation components, but operate entirely independently of one another.
The two leads at the center left (Red and Black) are the power leads. This circuit will require a regulated and filtered 5 Volt power supply. Actually 3-6 volts will do. The red lead is for the +5V power input. The Black lead is power ground. When several of these circuits are used, the power grounds for all must be connected together, usually this will occur at the power supply.
The leads and connection points to the left at the top or the bottom are for input signals and ground connections from detector circuits. If ground connections are needed, the six connection points immediately below the yellow leads may be used. Those are the connection points straight left of the integrated circuit. In this picture, no connections are present, because the ground connections of the associated detectors are wired straight to the same power supply which provides power to this circuit. Although it involves a little more wiring, you may prefer to run both the signal and ground connection from this board to the associated detectors. The ground connections are provided to support this wiring option.
The picture above shows a small white jumper installed which causes the signals to be lighted at all times. This point can optionally be connected with a Green lead to a detector in the block which approaches the signal so the signal lights only when a train is approaching.
The Red lead should be connected to the detector for the block immediately past the signal. A detection signal at this lead will light the red signal.
The Yellow lead should be connected to the detector for the second block past the signal to indicate presence of a train two blocks ahead. If yellow caution signals are not used, the yellow wire can be deleted.
Note: the detectors work by effectively shorting the green, red, or yellow wire to ground (black) when a train is detected.
The bottom half is wired similar to the top, often, for the signal tower facing the opposite direction at the same location.
This picture is of a single control circuit which only controls a single signal tower.
The connectors at the right of the board are for connecting your signal tower leads. This circuit requires common-anode wired LEDs or separate leads from each LED so that the anodes can be connected together. If the leads from your tower are small 30 or 32 gauge wires, it is recommended you solder on a very short (1/4 inch) piece of bare 26 gauge (common telephone wiring) wire which will plug nicely into the sockets provided.
The Black (Top) connection is for the common anode. It is the positive lead for the LEDs. There is already a single 330 ohm current limiting resistor on the circuit board to prevent burning out your LEDs. Note: If you happen to be using mis-matched LEDs, you may need additional current limiting resistors (a few tens of ohms) to balance brightness between them.
The Green connection (Second from Top) is for the cathode of the Green (Proceed) LED(s).
The Yellow connection (Third from Top) is for the cathode of the Yellow (Caution) LED(s).
The Red connection (Fourth from Top) is for the cathode of the Red (Stop) LED(s).
The unmarked bottom connection is for the center of rotational signals which will usually always be on. If you use the green coincidence input connection, the center light will be lit only when a train approaches.
The Signal control circuit requires about 20 milliamps (.02 amps) of current to light two signals. This includes the current that lights the signal LED. If, for instance, your 5 Volt supply could supply only .1 amps, you should only connect 5 signal control boards to one power supply. Or, if your 5 Volt supply could supply 1 full amp, you would be able to run 50 signal control boards from it.