A tuned radio frequency receiver (TRF receiver) is a radio receiver that is usually composed of several tuned radio frequency amplifiers followed by circuits to detect and amplify the audio signal. A 3 stage TRF receiver includes a RF stage, a detector stage and an audio stage. Generally, 2 or 3 RF amplifiers are required to filter and amplify
Click here to download the full size of the above Circuit.
the received signal to a level sufficient to drive the detector stage. The detector converts RF signals directly to information, and the audio stage amplifies the information signal to a usable level. Prevalent in the early 20th century, it can be difficult to operate because each stage must be individually tuned to the station`s frequency. It was replaced by the Superheterodyne receiver invented by Edwin Armstrong. The TRF receiver was patented in 1916 by Ernst Alexanderson. His concept was that each stage would amplify the desired signal while reducing the interfering ones. The final stage was often simply a grid-leak detector. The radio schematic above shows a typical TRF receiver. This particular radio uses a six tube design utilizing triode tubes. It has two radio frequency amplifiers, one grid-leak detector/amplifier and three class A` audio amplifiers. The significance of the term "tuned radio frequency" is best understood when compared to the Superheterodyne receiver. A tuned radio frequency receiver actually tunes the receiver on the true radio frequency whereas the Superheterodyne receiver, tunes the desired signal after conversion to an intermediate frequency. Many homemade radios constructed by enthusiasts today, are tuned radio receivers, and these can range from single stage to multi-stage receivers. A problem with the TRF receiver is that interelectrode capacitance causes oscillations and other modes in the...
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: