The photodiode can be used to detect IR reflected from the object. However, IR produced by the ambient conditions also detected by the photodiode. This IR noise must be filtered to prevent false detections. Usually, the LED`s IR signal is modulated with a convenient frequency and then using that modulation to detect only IR to filter the IR noise.
Click here to download the full size of the above Circuit.
So, the photodiode will detect only IR reflected from the object. This method can be simplified by using the IR proximity sensor that has simple receiver and transmitter sections. Here is the schematic diagram of the IR proximity sensor : The transmitter of this circuit consists of a 940nm IR LED (IR11-21C). To turn ON and OFF the IR LED, the a 10kHz oscillator frequency is used. we can control the detection and the level of transmitted power by varying the LED current. The transmit pulses of this transmitter have a small duty cycle (typically 10%), to save power. The Op amp is biased at 2. 5V because there no input IR signal present. The op amp output varies around 2. 5V with a dynamic range of 5V because of a 10kHz IR signal incident. The output drives a simple diode detector. A DC signal proportional to its amplitude can be provided by a simple diode detector. Simple diode detector also rectifies the 10kHz signal. The output signal is an analog signal that is proportional to the distance of the object from the IR transmitter. We can fed the output signal to an ADC for further processing or use it directly. [Source: MAXIM Application Note] We aim to transmit more information by carrying articles. Please send us an E-mail to wanghuali@hqew. net within 15 days if we are involved in the problems of article content, copyright or other problems. We will delete it soon.
This project fits more for custom made battery casing that can have more space to hide things inside. This switch with few alterations can be used for any other project as well but is designed based on e-bike needs! This project use a clever functionality of....
The circuit described here uses ultrasonic oscillations and operates based on the propagation velocity of these oscillations in the air. Thus, we can easily determine the distance of two points if the time within which the wave travels this distance is....
Sometimes the precious metals are hidden too deep and are not detected except with complicated devices. In many cases, however, small pieces of precious metal buried near the surface can be detected by relatively simple means. Everyone is very attractive to....
Many times for various reasons we forget or can not water the plants that we have in our homes. And many humidity sensors units just notify us with a beeping sound or with a flashing light, that the pot needs watering. But what if we are away from home? This....
The principle behind a metal detector is really very simple. Proof of this is the circuit that follows, in which it proves that the construction of a metal detector can be done in the minute, with few components that we find very easily everywhere. With the....
The sub-harmonic bass generator is a sound producing unit for guitars. The sound it produces looks very much like that of the bass guitar. The octave generator is sometimes quite unusual since it does not produce any of the usual ways of coloring the sound,....
In the past the sounding (sea bottom measurement) was done with the "bullet", that is, with a heavy lead object that the seamen plucked into the sea hung from a calibrated rope. As soon as the "bullet" reached the bottom, the depth appeared directly from the....
This Amplifier was designed to have the following specifications: Distortion less than 0.1% at full power of 100W even at 20KHz. Power has to be attributed to an extended bandwidth. The output transistors must be protected against short circuits. The power....
A series of LEDs serve to alert the gardener when plants need water. Using two conventional digital integrated LEDs and a series of LEDs, we make a very useful device for gardening. The device detects the amount of water in the pot and alerts the grower.....
characters left: