Menu English Ukrainian russian Home

Free technical library for hobbyists and professionals Free technical library

Free library / Schemes of radio-electronic and electrical devices

Simple FM receiver. Encyclopedia of radio electronics and electrical engineering

Free technical library

Encyclopedia of radio electronics and electrical engineering / radio reception

Comments on the article Comments on the article

For a long time, a huge number of circuits of simple HF receivers were published in magazines, but there was nothing similar for the VHF band. We will try to correct this omission. The circuit was originally designed as part of a school project.

scheme a simple FM receiver is shown in the figure. It consists of a TR1 regenerative RF stage and a TR2-TR4 two- or three-stage audio amplifier. In some areas with reliable reception, there is no need for a three-stage VLF, in this case, the TR3 transistor and the corresponding components can be omitted, and the free terminal of the capacitor C5 can be connected to the collector of the TR2 transistor.

Simple FM receiver
(click to enlarge)

The most critical part of the circuit is the first stage, TR1 / VC1, here the connections should be made with as short conductors as possible. Coil L1 contains 8 turns of 1mm (20 SWG) enamelled copper wire on a 6mm mandrel. After winding, the coil should be stretched to a length of 13 mm for further adjustment.

Tuning capacitor VC1 is used from a two-section capacitor with a trimmer from a pocket receiver, one section is used. The "mass" of the capacitor VC1 is connected to the capacitor C1, the capacitance of which is 22pF. The inductance of the RF inductor L2 is not critical and can be in the range of 1 μH ... 10 μH.

The output stage is designed to work on headphones from the player, the windings of which are connected in series to obtain a resistance of 64 ohms (connect to the outermost and ring contact of the plug).

For settings Receiver potentiometer VR1 must be slowly rotated (towards the output connected to the "+" power supply) until, somewhere in the middle, there is a sharp increase in noise, signaling the beginning of generation. After that, the potentiometer should be slightly turned in the opposite direction, very slowly, so that the generation stops. Now you can tune in to a radio station. The frequency range 87MHz ... 108MHz should be set using the VC2 trimmer at the upper limit (108MHz) of the range, and by compressing / stretching the L1 coil at the lower limit (87MHz).

The receiver has been tested in various locations in three different countries, including England, and has always been able to receive several radio stations at good volume.

Author: Francis Hall, Meinershagen, Germany

See other articles Section radio reception.

Read and write useful comments on this article.

<< Back

<< Back

Latest news of science and technology, new electronics:

Blinking of the magician and his audience 19.05.2024

Magic and illusions have always captured the attention of the public, but what happens behind the scenes of the magician and in the brains of his audience? Scientists from the UK decided to solve this mystery by conducting a new study involving ten illusionists of varying experience. Illusionists, some of whom had been practicing magic for more than half a century, others for only six months, were invited to demonstrate the same trick - the popular coin trick. Recordings of their performances during training and on stage showed that each of them began to blink significantly more often at the moment of performing the trick. The study's findings indicate that magicians' blink rate may be related to unconscious aspects of their performance. At the same time, as scientists have found, spectators also begin to blink more often, following the movements of the illusionist. This observation supports the idea that magicians may be catalysts for blinking in audiences. Additional research has shown that magicians blink more often during ... >>

Ultrasonic coffee machine 19.05.2024

Iced coffee has become an integral part of coffee culture in recent years. Therefore, engineers from the University of New South Wales decided to improve its preparation. They have developed an ultrasonic coffee machine that reduces the cold brew time for ground coffee beans from 12-24 hours to significantly less time. Iced coffee, or "Cold brew", is popular due to its smoothness, low acidity and low bitterness. It is prepared by steeping ground coffee in cold water for a long time. Unlike traditional hot brewing, which often imparts bitterness to coffee, cold brewing extracts more delicate and complex flavors from the coffee beans. The innovative system, presented by a team of engineers, introduces ultrasonic technology into the coffee preparation process. The system uses ultrasonic waves to speed up the process of extracting oils, flavor and aroma from ground coffee. This allows you to significantly reduce the time ... >>

The speech of sperm whales is similar to that of humans 18.05.2024

In the world of the ocean, where the mysterious and unknown coexists with the studied, sperm whales, with their huge brains, are of particular interest to science. Researchers, working with a huge array of audio recordings collected during the Dominica Sperm Whale Project (DSWP) - more than 8000 recordings, seek to unravel the secrets of their communication and understand the structure and complexity of the language of these mysterious creatures. By studying in detail the recordings of 60 sperm whales in the eastern Caribbean, scientists have revealed surprising features of their communication, revealing the complexity of their language. "Our observations indicate that these whales have a highly developed combinatorial communication system, including rubato and ornaments, which indicates their ability to quickly adapt and vary during communication. Despite significant differences in evolution, sperm whales have elements in their communication that are characteristic of human communication," says Shane Gero, a biologist at Carleton University and director of the CETI project. Issl ... >>

Random news from the Archive

The danger of antiseptics 09.07.2020

The use of antiseptics containing methanol can lead to serious illness and even death.

According to the US Food and Drug Administration (FDA), cases of skin antiseptic poisoning have increased significantly in recent years. Some samples of skin preparations tested positive for methanol contamination during the study. This substance is known to be toxic and can cause poisoning if it comes into contact with it through the skin or mucous membranes of the body.

American experts have uncovered several cases of methanol poisoning, which led to blindness and even death. The FDA recommends that consumers stop buying dangerous antiseptics and seek medical attention at the first sign of poisoning. Methanol can cause nausea, headache, partial or complete loss of vision, convulsions, and large doses can lead to coma or death.

Children are most at risk of methanol poisoning, as they may accidentally ingest skin antiseptic. The Bureau also reminded of the need to wash hands with soap for at least 20 seconds after visiting public places, using the toilet, sneezing and before eating.

Other interesting news:

▪ Diet improves mood

▪ Cold computer memory

▪ Ultra-compact 16-bit microcontroller MB90F455/456/457

▪ MFP Stylus Photo RX600

▪ Impossible black hole discovered

News feed of science and technology, new electronics


Interesting materials of the Free Technical Library:

▪ section of the site Audio and video surveillance. Selection of articles

▪ article Our mutual friend. Popular expression

▪ Do humans have teeth the same as animals? Detailed answer

▪ Firmian's article is simple. Legends, cultivation, methods of application

▪ article Voltage addition in the welding machine. Encyclopedia of radio electronics and electrical engineering

▪ article Economical, sensitive, stereo radio receiver. Encyclopedia of radio electronics and electrical engineering

Leave your comment on this article:


Email (optional):

A comment:

All languages ​​of this page

Home page | Library | Articles | Website map | Site Reviews