11-02-2013, 12:32 PM
SPEED CHECKER FOR HIGHWAYS
SPEED CHECKER.docx (Size: 21.83 KB / Downloads: 39)
ABSTRACT
While driving on highways, motorists should not exceed the maximum Speed limit permitted for their vehicle. However, accidents keep occurring due to speed violations since the drivers tend to ignore their speedometers. This speed checker will come handy for the highway traffic police as it will not only provide a digital display in accordance with a vehicle’s speed but also sound an alarm if the vehicle exceeds the permissible speed for the highway. The system basically comprises two laser transmitter-LDR sensor pairs, which are installed on the highway 100 metres apart, with the transmitter and the LDR sensor of each pair on the opposite sides of the road. The installation of lasers and is shown in Fig. 1.
Construction and working
Assemble the circuit on a PCB. An actual-size, single-side PCB layout for the speed checker is shown in Fig. 4 and its component layout in Fig.5.Before operation, using a multimeter check whether the power supply output is correct. If yes, apply power supply to the circuit by flipping switchS3 to ‘on.’ In the circuit, use long wires for connecting the two LDRs, so that you can take them out of the PCB and install on one side of the highway,100 metres apart. Install the two laser transmitters (such as laser torches) on the other side of the highway exactly opposite to the LDRs such that laser light falls directly on the LDRs. Reset the circuit by pressing switch S2, so the display shows ‘0000.’ Using switch S1,select the speed limit (say, 60 kmph) for the highway. When any vehicle crosses the first laser light, LDR1 will triggerIC1. The output of IC1 goes high for the time set to cross 100 metres with the selected speed (60 kmph) and LED1glows during for period. When the vehicle crosses the second laser light, the output of IC2 goes high and LED2glows for this period. Piezo buzzer PZ1 sounds an alarm if the vehicle crosses the distance between the laser set-ups at more than the selected speed (lesser period than preset period). The counter starts counting when the first laser beam is intercepted and stops when the second laser beam is intercepted. The time taken by the vehicle to cross both the laser beams is displayed on the 7-segment display. For 60kmph speed setting, with timer frequency set at 100 Hz.