If you want to interest your children in technical creativity - try to make a detector radio with them. The advantage of such a receiver is that it does not need an external power supply. You will surely like this homemade product, and the children will look at it as if it were a real miracle. It will be possible at the same time to explain to them the nature of radio waves.
It is necessary
- Wire with enamel or silk insulation with a diameter of 0.3-0.6 mm
- Round ferrite bar from an old radio
- Notebook sheet
- BF or nitrocellulose glue
- Capacitor 1500-4000 pF
- Terminals
- Antenna sockets, for grounding, for telephones
- High impedance telephones or low impedance telephones and a step-down transformer (for example, output from an old radio, TVK from an old TV, or a transformer from a broadcast speaker)
- Diode semiconductor point germanium (for example, D9, D2, D18, GD507, D310)
- Antenna wire bare copper with a diameter of 3-5 mm (antenna cable can be used) 15-20 m
- Copper stranded wire insulated
- Plate made of insulating material - getinax, textolite, plexiglass
- Soldering iron
- Drill
Instructions
Step 1
Wrap a strip of paper 7-8 cm wide on the ferrite core. Wrap the paper in several layers, securing them with BF glue so that you get a tight paper cylinder. The cylinder should slide easily over the ferrite core after drying.
Step 2
Wrap 100 turns of wire with enamel or silk insulation on the resulting cylinder. Coil the wire turn by turn. Secure the ends of the winding with glue. The result is a coil, which is designated L1 in the diagram.
Step 3
Assemble the receiver according to the indicated diagram. The polarity of switching on the diode in this case does not matter. Connect high-impedance headphones (telephones) to the receiver output. If you don't find them at hand, you can use low-impedance headphones - for example, from a player. But they can only be connected via a step-down transformer. In this case, the high-impedance winding of the transformer is connected to the output of the receiver, and the headphones are connected to the low-impedance winding.
Step 4
A detector receiver cannot work without a good antenna and grounding. Make grounding. Use flexible stranded wire to connect the ground lead of the receiver to the paint- and rust-free central heating radiator pipe. It is even better to connect this branch with a metal object buried in the ground to a depth of 1-1.5 m. It is desirable that in this place and at this depth the earth was moist.
Step 5
It is recommended to place the antenna as high as possible. For example, on the roof of a house. You can throw it onto a tall tree with the help of a load. As a last resort, place it around the perimeter of the room in your apartment building. True, such an antenna will not work in a reinforced concrete house. The antenna is a bare copper wire 15-20 m long.
Step 6
Tune the receiver to the radio by moving the ferrite bar inside the inductor. If it turns out that no radio station falls within the tuning range or is faintly audible at the end of the range, make another coil, with more or less turns. Typically a coil can have 60 to 220 turns.
