We all live in a world obsessed with technology. Almost everyone has a mobile phone Teenagers mostly indulge in social media like Facebook, Twitter etc. . The basic lifeline of all these communication is the “Internet”. No disaster comes with a prior notice. Imagine a situation after a natural disaster where there is no internet, mobile network, land line or any other digital communication.
Then comes our old grandpa style but totally safe AM transmitter and receiver. These things remain off grid from internet and other digital connections. It is very easy to make and simple. Spies have been using it since World War I as a bug . These days most mobile phones also don’t have FM support. In this situation a handy AM Transmitter can be a life saver.
Things you need
These are some of the basic things that you need to build a small AM Transmitter.
Building the device: I didn’t have many things with me so I had to buy many things from market. For Nepalese living in Kathmandu I recommend Bhedasing, Bangemudha. For a mic as an input device I broke my old headphone of PC. Audio transformer was very hard to find than Crystal Oscillator. People living in US can easily buy from Radio Shack. Please refer the schematic diagram below to build the device.
Also Read: Homemade Arc Welder
The 1000 ohm winding of transformer is connected to mic as shown then the one end of 8 ohm winding is connected to positive lead of battery and another end is connected to one end of 1 MHz Oscillator. The negative lead of battery is connected to another point just below the antenna’s point. One terminal of oscillator is left open as shown. Use connecting wires of suitable size and solder them so that they will have a strong set.
You can use a audio input jack such as 3.5 mm jack to feed in audio from other source. The audio emitted by this transmitter can be easily caught by normal AM radio but you should not make the antenna bigger than 12 inches because this can interfere with others signals too.This project should be kept small as possible. I recommend extending the antenna only in the case of emergency. Lets hope such incident never happen.