The transmitter used is a transducer that converts a 40 khz square wave being sent by an oscillator/decoder into a sinusoidal sound wave at the same frequency. The transducer itself consists of a square of piezo-electric ceramic materials with metallised electrode surfaces deposited on its faces, in order to convert the electrical signal into ultrasonic wave.
Specification: Bandwidth > 6khz, Operating voltage » 10v
2.1 The transducer is then detecting the echoed sound wave and converting it back into a 40khz voltage sinusoidal signal. It also acts as a filter owing to its narrow bandwidth, hence maintains the accuracy of the detection.
2.2 The transistor is used to amplify the incoming signal from the transducer in order to acknowledge the decoder/oscillator the reception of the echoed signal.
A LM567 IC chip is used as a pulse generator (oscillator) and tone decoder in this project. Also another load is used ensure the incoming signal is amplified before input into the decoder. The LM567 will decode the signal and send it to Pin8. If the received signal is detected by the phase detector in the decoder as in phase with the transmitted signal, then a logic LOW will be generated at Pin8. Pin8 is connected to the micro-controller to proceed for pulse counting.
This is the hard core of the entire circuitry. It features the counting of pulse width in order to find the time elapsed for an echo, also the arithmetic calculation based on the programming, which works out the actual distance between the target and the detector. And then the F1 Board will display the result on the 7-segment-display LEDs. (for detail see later session)
The latch is a type of 74LS373 TTL chip. It switches the output from the F1 Board to the 7-Segment-Display LEDs
This consists of an OPTO FND 507/537/350/357 type of LEDs. The certain connections that determine the illuminations of each LED are to be discussed in the F1 Board section. A pull down resistor of 1kW is used to limit the voltage across the LED before it is lightened up.
Power supply
Also as in every electrical circuit the power supply is presented to bring the essential energy to each and every individual component. A set of batteries providing 9 volts voltage and a voltage regulator are needed for the power supply of the circuit.
Communication
Engineering 2nd. year undergraduates:
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