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18-03-2007, 11:31 AM
اعمل راديو بثلاث قروش
Building a Three-Penny Radio.
A crystal radio is nice because it needs no power, and the materials can all be home-made or at least found around the house. But the crystal radio needs a big antenna, and a good ground, and so is not very portable.
To get away with using a much smaller, portable antenna, we will need to amplify the tiny signal it receives. This requires a portable power supply, such as a battery.
Our next toy is a portable radio. It can be powered from a tiny 1.5 volt battery, or from a battery made from copper wire and aluminum foil sitting in a glass of lemonade, a soft drink, or a beer, or by a few small commercial solar cells.
The heart of the radio is a special 10 transistor integrated circuit in a tiny three-legged bit of plastic. This circuit comes ready-made with several amplifiers, the detector, and an Automatic Gain Control circuit that boosts the level of faint stations to match the strong ones, so no volume control is needed. The final radio has excellent performance, pulling in weak stations, and preventing nearby strong stations from overwhelming the weak ones next to them on the dial.
We call the radio a "Three Penny" radio because we use three shiny pennies as anchors for the various parts the radio needs. This makes the construction very easy.
If you have never soldered anything before, this is a great project to start with. It is very forgiving of the type of soldering usually done by beginners, and all the parts are widely separated, making the job much easier than with other circuits. Soldering irons and solder are inexpensive tools you can find at a local electronics store such as Radio Shack.
http://sci-toys.com/scitoys/scitoys/radio/three_penny/small_cap_across_ic.jpg
للمزيد من المعلومات قم بزيارة الموقع التالي (http://sci-toys.com/scitoys/scitoys/radio/three_penny/three_penny.html)
Building a Three-Penny Radio.
A crystal radio is nice because it needs no power, and the materials can all be home-made or at least found around the house. But the crystal radio needs a big antenna, and a good ground, and so is not very portable.
To get away with using a much smaller, portable antenna, we will need to amplify the tiny signal it receives. This requires a portable power supply, such as a battery.
Our next toy is a portable radio. It can be powered from a tiny 1.5 volt battery, or from a battery made from copper wire and aluminum foil sitting in a glass of lemonade, a soft drink, or a beer, or by a few small commercial solar cells.
The heart of the radio is a special 10 transistor integrated circuit in a tiny three-legged bit of plastic. This circuit comes ready-made with several amplifiers, the detector, and an Automatic Gain Control circuit that boosts the level of faint stations to match the strong ones, so no volume control is needed. The final radio has excellent performance, pulling in weak stations, and preventing nearby strong stations from overwhelming the weak ones next to them on the dial.
We call the radio a "Three Penny" radio because we use three shiny pennies as anchors for the various parts the radio needs. This makes the construction very easy.
If you have never soldered anything before, this is a great project to start with. It is very forgiving of the type of soldering usually done by beginners, and all the parts are widely separated, making the job much easier than with other circuits. Soldering irons and solder are inexpensive tools you can find at a local electronics store such as Radio Shack.
http://sci-toys.com/scitoys/scitoys/radio/three_penny/small_cap_across_ic.jpg
للمزيد من المعلومات قم بزيارة الموقع التالي (http://sci-toys.com/scitoys/scitoys/radio/three_penny/three_penny.html)