Multi-Function Crossing Signal Controller
Building the Kit
Click here to jump to the new IR Trigger modification
Click here for the new IR sensor notes
The parts for the kit are shown below. Clockwise from the upper left they are:
In addition you will need a power supply or batteries, solder, soldering iron, wire cutters, etc. Missing from the photo are the three jumpers that select modes.
Solder the 7805 voltage regulator, capacitor and power pins to the circuit board. Note the orientation of the 7805 and capacitor. The red/black cable attaches to a source of 7-20 volts DC.
Clip off leads that extend through the board. Check carefully for solder bridges, they are easy to miss!
Solder the 14 pin socket to the circuit board. Be careful that all 14 pins come through the holes in the board as it is easy to bend one over. Also note the orientation of the socket. Pin 1 is in the upper left in this photo. The four pins above the socket are not needed unless you plan on reprogramming the PIC processor.
Check after soldering each component to be certain that there are no solder bridges. The socket pins are very close together and bridges are easy to create.
Add the four resistors and the two transistors. The transistors must be oriented as shown. The 1K resistors are behind the transistors and the 10K resistors are at the bottom of the photo. Resistors can be installed either way.
Carefully insert the microcontroller making sure that no pins are bent under - note that pin 1 (marked with the dot at the bottom left in the photo) has to been located as shown! There is also a notch at the left end that marks pin 1, too.
Again, check for bridges and clip leads close to the board.
Install and solder the two potentiometers and the four sets of pins as shown.
This photo shows the three mode selection jumpers installed (bottom left) and the plugs for the two LEDs or incandescent bulbs. If using LEDs the red wire must go to the left as shown.
Solder the 470 ohm current limiting resistors to the LEDs.
A revised board is now being used with this project. The photos below will highlight the differences between the two boards
The pins in the upper right corner are easier to install and solder if there are jumpers on them as shown.
Note that the mode selection pins are longer on the end that extends above the board.
The red / black wires on the left are power for the board - 7.5 to 12 volts
The two pairs of red / black wires in the lower right go to the two LEDs. The current limiting resistors are at the ends of these wires.
New IR Sensor
A new, self contained IR sensor can easily be connected to the circuit. It requires a three wire connection, +5 volts, ground and data. I use a 3 wire servo cable with the wires rearranged.
This photo shows the completed board conected to two test LEDs and the IR sensor - the end of the sensor with the two black plastic lenses is pointed towards the item to be detected.
The IR sensor has a three wire cable. The red wire goes to 5 volts, the black to ground and the yellow goes high when an object is detected. A 3 wire male servo cable is used to connect the sensor to the circuit board.
The yellow from the sensor goes to the white wire on the servo cable and is soldered to the inner connection to the first trigger on the circuit board. The connection is circled in yellow. The red and black wires are soldered to the positive and negative pads for the small yellow capacitor.
This photo shows the sensor connected to the servo cable and the two test LEDs.
The sensitivity (range) of the sensor can be adjusted by turning the small screw on the back of the sensor, circled in yellow. Turning it counter clockwise makes it less sensitive and turning it clockwise makes it more sensitive. The small red LED beside it lights when an object has been detected.