The overall task of the optical receiver is to extract the information that has been placed on the modulated light carrier by the distant transmitter and restores the information to its original form. The typical through-the-air communications receiver can be broken down into five separate sections. These are: light collector (lens), light detecto
Click here to download the full size of the above Circuit.
r (PIN), current to voltage converter, signal amplifier and pulse discriminator. There may also be additional circuits depending on the kind of the signal being received. As an example, a receiver that is extracting voice information will need a frequency to voltage converter and an audio amplifier to reproduce the original voice signal. Computer data receivers will also need some decoding circuits that would configure the transmitted serial data bits into 8 bit words. However, this section will concentrate on the circuits needed for processing voice information. Volume II of this book will contain additional circuits for digital data receivers. As discussed in the section on light detectors, the silicon PIN photodiode is the recommended detector for most all through-the-air communications. Such a detector works best when reversed biased. In the reversed biased mode it becomes a diode that leaks current in response to the light striking it. The current is directly proportional to the incident light power level (light intensity). When detecting light at its peak spectrum response wavelength of 900 nanometers, the silicon PIN photodiode will leak about 0. 5 micro amps of current for each microwatt of light striking it. This relationship is independent to the size of the detector. The PIN photodiode size should be chosen based on the required frequency response and the desired acceptance angle with the lens being used. Large...
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: