Buy Project Set 4
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| IR Sensor |
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| In this PR, we will put more concerns on the working principle of infrared sensor and the output from it. PIC microcontroller and programming are not required. |
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| IR (Infra-Red) is the typical light source used as a sensor in hobby robot to sense opaque object. The basic principle of IR sensor is based on an IR emitter and an IR receiver. IR emitter will emit infrared continuously when you provide power source to it. Since there is no source of power for IR receiver, it would not emit any light. It will only receive infrared if there is any. Usually we will attach the IR emitter and IR receiver side by side, and point them to a reflective surface. |
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| When the IR receiver receives infrared, it will generate voltage at its pin. The generated voltage is in the range from 0V to 5V depends on the intensity of infrared it received. The voltage will drop to zero if there is no infrared received. The problem arise where our microcontroller only recognize digital input which is 0V and 5V. If the infrared reflected is less, the receiver would probably produce a 2V or 3V and microcontroller is unable to deal with these analog values. Thus, we need a comparator (LM324) to solve this problem. By using this comparator, the output voltage from IR receiver will compare to an input voltage through a variable resistor. The comparator able to compare both input voltage and generate either 0V or 5V where we can connect it to our microcontroller. |
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| Buy Project Set 4 |
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