This article will review the scheme radios, analyzed the work of the simplest designs.All of you know that there are several ranges of radio waves.And all of them are divided into broadcasting for cellular communication for official use only and amateur radio.Broadcast radio is made in mid-range (AM, DM), long (LW, LW), VHF (FM, FM) waves.Now you will learn how to make a simple device for receiving radio stations.
Detector radio
This design makes every beginner radio amateur.And by the power to collect it, even a child, because it is no big deal.To produce, you will need to acquire the following elements:
- variable capacitor.
- Permanent capacitor more than 4700 pF.
- headphones with an impedance of 1500 ohms winding more.Perfect TON-2.
- type semiconductor silicon diode D9.However, you can use any more modern high.
- copper wire and the mandrel diameter at least 40 mm.
The above schematic diagram of the radio allows you to understand how to carry out connection of all components.Particular attention should be paid to the design of the antenna, ground, inductors.Of these elements must be discussed separately.The detector radio can work in a range of medium and long waves, so it needs a full-fledged operation of the antenna.
antenna design, grounding coil
to radio circuits in the article, operating in the MF, LF, HF, is necessary to make the antenna.It is made from a length of wire.You can use multi-core insulation, the main thing that it was a cross-section of more than 0.75 square meters.mm.But not too thick to use.The length of the fabric antenna is considered on the basis of the frequency at which the radio will work.The length of fabric should be a multiple of the value of frequency expressed in meters.When it comes to the range of 90 meters (3200 kHz), the length of the antenna must be at least 10 m. It must be suspended at a height of at least 3 meters, and carefully insulate the walls, trees, poles.
as ground heating pipes can be used.However, the ideal option would be a metal pin driven into at least one meter into the ground.The coil is wound with copper wire only.Moreover, it must be thicker than 0.75 mm, for empowerment can make objections.A coil wound on a solid mandrel ends securely fastened.Please note that you need a minimum of 90 turns to wind, so try to trim a mandrel as long as possible.These schemes are good only radios that they can understand the operation of such devices.However, its sensitivity is extremely low, so it can be used to listen only powerful radio station.Even the connection to an external amplifier bass will not save.
radio on a chip
Above is a diagram of a radio receiver on the chip K174HA34.This small item collected several nodes - detector, a frequency converter, a signal amplifier.Of course, this chip is outdated, but it is still produced, and its cost is very low.What else is necessary to begin radio amateurs?If even spoil the element, it is not a pity.There are also foreign counterparts, allowing to produce radios for VHF, and their cost is not very high.This scheme is good that there is no scarce items, but it can receive radio stations in the broadcast range.One drawback - the need to produce an additional low-frequency amplifier, as the output of the chip is very weak signal.
Conclusion
little understanding to the design of radios, you can start making more complex devices.Modern element base allows not only to make their own receivers, amplifiers, and transmitters that will be useful during outdoor recreation, for construction works, as well as for driving.For example, for the implementation of the automatic start.In other words, the circuit is so functional radios that are used everywhere today.
