16-07-2012, 03:47 PM
ALARM RINGING CONTROL
ALARM RINGING CONTROL.doc (Size: 962 KB / Downloads: 65)
INTRODUCTION:
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 thehighway. 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 LDRs is shown in Fig. 1. The system displays the time taken by the vehicle in crossing this 100m distance from one pair to the other with a resolution of 0.01 second, from which the speed of the vehicle can be calculated as follows: As per the above equation, for a
speed of 40 kmph the display will read 900 (or 9 seconds), and for a speed of 60 kmph the display will read 600 (or 6 seconds). Note that the LSB of the display equals 0.01 second and each succeeding digit is ten times the preceding digit. You can similarly calculate the other readings (or time).
Circuit description
This circuit has been designed assuming that the maximum permissible speed for highways is either 40 kmph or 60 kmphas per the traffic rule.The circuit is built around five NE555 timer ICs (IC1 throughIC5), four Cd4026 counter ICs (IC6 through IC9) and four 7-segmint displays (DIS1 through DIS4). IC1 through IC3function as monostables with IC1 serving as count –startmono, IC2 as count –stop mono and IC3 as speed-limitdetector mono, controlled by IC1 and IC2 outputs. Bistableset-reset IC4 is also controlled by the outputs of IC1 and IC2and it (IC4), in turn controls switching on/off of the 100Hz(period=0.01 second) astable
Speed Checker for Highways
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 thehighway.
Various 8051 microcontrollers
8051 microcontrollers use two different kinds of memory such as UV- EPROM, Flash and NV-RAM. Hence 8051 will not be seen in the part number even though it is the most popular member of the 8051 family.
8751 – This microcontroller is the UV-EPROM version of 8051. This chip has only 4K bytes of UV-EPROM. It is required to have access to the PROM burner and the UV-EPROM eraser to erase the contents inside the chip before it is programmed again. The disadvantage of using this memory is the waiting time of around 20 minutes to erase the contents in order to program it again. Due to this limitation, manufacturers fabricated flash and NV-RAM versions of 8051.