Acquaintance with the fascinating world of radio can begin with the manufacture of simple schemes that will give a good practical experience to a novice ham radio. To begin with, it is possible to assemble a detector receiver, its manufacture has long become a good tradition for radio amateurs. It is simple in manufacturing, and it can be done in just a few hours. This requires a minimal and accessible set of parts and, of course, a desire to work. The first experienced detector receiver is different in that it can be changed, it does not need to develop and manufacture a printed circuit board, it is easy to adjust, since all the parts fit on the table.
Prepare the necessary parts for the manufacture of the device. The detector receiver consists of a semiconductor point diode (D9, D2), which will be a detector. A set of capacitors of up to several thousand picofarads, a ferrite rod (diameter 7-8 mm) of the brand 400HH, 600HH and a length of up to 140 mm. It is also necessary to prepare a PEV-1,2 wire (0.15-18 mm) and any high-resistance phones with a coil resistance of at least 1500 Ω. All these radio components can be bought at a specialized store.
Now let's stop on manufacturing a coil for a ferrite rod. To do this, wrap a few layers of loose paper on the ferrite core and glue them together. Should get a tight frame, which is easily removed from the rod. Now we wind up three hundred turns of pre-prepared wire and make bends every five turns. The main mistake of those who first make their detector receiver is that every fifty turns of wire bite off, be cleaned and serviced. Leave this operation for later, in the process of winding just enough to make bends and continue winding the wire. The resulting coil should be glued with paper glue and allow it to dry.
Now we will collect all the details according to a simple scheme. The end of the coil and the diode anode are connected to the receiving antenna. The other extreme bend is connected to the ground and one of the headphone pins. The second output of the headphones is connected to the cathode of the diode. Everything, you have collected your first radio yourself. If all of the receiver's circuits are assembled correctly, it starts working immediately. The adjustment of the device is carried out by changing the number of turns on the coil and selecting the capacity of the capacitor, which is connected in parallel to the headphones. With this help we achieve the best possible sound.
Such a receiver catches radio transmissions of nearby stations working on medium-wave and long-wave bands. The next stage can be the production of one-, two-, and more cascaded receivers, which can accept a much larger number of stations. And in the future, you can make a scanning receiver, which automatically finds the station and remembers it. The more complex the circuit of the device, the greater the possibilities in it. But for proper tuning of such a receiver it is necessary to have in your home laboratory good test instruments, a high frequency oscillator, an oscilloscope, etc.