DIY a radio in 10 minutes
Author:Geekfans Date: 06/25/2018
Step 1: Materials Needed
A ferrite loop antenna coil, ferrite magnet can move in and out of the coil for coarse tuning.
An adjustable capacitor.
One germanium diode.
A piezoelectric headset.
Two spring clip wire jumpers.
15M long stranded insulated wire as antenna, you can use TV or radio antenna as an alternative.
A wooden board or other thing as a base.
It is really a simple radio, pls see the pic above.
The black wire on the coil is connected to the lead in the middle of the adjustable capacitor, and the other wire is connected to the right.
The germanium diode is connected to the rightmost lead of the adjustable capacitor.
One wire of the earphone is connected to the free end of the germanium diode, and the other wire is connected to the lead in the middle of the adjustable capacitor.
The red line is connected to the antenna, and the green line is connected to the earth wire .
Step 2: Listen to Radio
First adjust the adjustable capacitor to the middle.
Put on headphones and slowly move the ferrite magnet into the coil and listen carefully to the radio.
With a long antenna, you can receive several channels. In some areas, the signal of one or two channel may be too strong and it can cover the signals of other channels.
How do magnets change frequency?
The magnetic bar increases the inductance of the coil. As the bar is inserted into the coil, more coils are affected by the bar and the inductance increases. The ferrite magnetic bar is used because it is magnetic and non-conductive. If it conducts electricity, eddy currents will be generated in the coil and energy will be wasted.