Even a novice radio amateur can make a simple receiver. Such a receiver is called a detector receiver. Its design is very simple, although the device contains all the structural elements necessary for receiving radio transmissions. Arm yourself with a soldering iron, let's get to work.
The choice of the wave of the desired radio station is carried out in the detector receiver using a resonant circuit consisting of an inductor L and a capacitor C. The signal is extracted from the sum of signals from various radio stations and enters the detector D, which converts a high-frequency radio signal into a low-frequency sound signal and transmits it to headphones (headphones).
To set up a detector radio, you need the following parts: inductor (L), 220pF ceramic capacitor (C), receiving antenna (A), ground (Z), diode detector (D), headphones of any type (T).
The receiver does not contain tube or transistor amplifiers and does not have a power supply. Therefore, the signal to the headphones is rather weak. An external antenna with a length of at least 15 m and grounding (a piece of copper wire connected to a water pipe) will serve as a guarantee of good radio signal reception.
Make an inductor. On a frame made of insulating material with a diameter of 15 mm, wind 100 turns of enameled wire with a diameter of 0.3 mm. Every 10 turns, make a loop pin.
Insert a piece of ferrite core with a diameter of 10 mm and a length of 150 mm into the tube. You do not need to fasten it yet, you will need it to fine-tune the receiver.
The main thing when assembling the receiver is the selection of coil leads for connection to an external antenna and diode. Find the conclusions experimentally. Your task is to find the output at which the headphones will have maximum audibility at one of the middle positions of the ferrite rod inside the coil.
Second tuning method: After tuning the resonant circuit, attach the ferrite rod inside the coil and locate the headphone terminal that achieves the maximum signal volume.
After selecting the conclusions, carefully solder the circuit elements.
The action of the receiver will not depend on the relative position of the elements on the circuit board, so they can be positioned in different ways. It is very convenient to mount parts in a small plastic box.
If the transmitting station you are tuned in is close to you, you will get a very good loud signal in the headphones. It all depends on the subtlety of tuning, the quality of the antenna and grounding.