FM / MW / SW Radio as Tri-band Transceiver ( full duplex transmission )

In this project i will introduce a full duplex radio communication from  FM / MW / SW Radio.For this we will use two radio sets ,( Digital or Analog Radio set ) just keep two radio sets near each other , tune one of the radio having same band you will observe that both radios will become silent at one tuning point , This is because of local oscillators in both radios , both radios will receive each other local oscillator frequency. Local oscillators are used in superheterodyne receiver for obtaining first IF stage (10.7 MHz ) every coming station frequency output will be remain 10.7 MHz because local oscillator frequency , than another IF stage 455 KHz  and station frequency will simultaneously tune. It means that if want to receive 100 MHz on radio , then local oscillator frequency will be 110.7 MHz , 100+10.7 = 110.7 , 110.7 MHz - 10.7 MHz = 100 MHz  ( At 100 MHz station frequency local oscillator will be having 110.7 MHz ) for having output 10.7 MHz by adding 2 or 3 stages of RF amplifiers a professional transceiver can be made specially for Car Radio. Here in this project actually local oscillator frequency will be amplified , with a fix frequency stability In this case i am going to work on Medium Wave Radio ( MW ) , Here we require 450 KHz at incoming every station , at 1413 KHz local Oscillator frequency will be 1863 KHz  it will be than mixed  & output will be 450 KHz 
1). 1863 KHz - 1413 KHz = 450 KHz  === 1413+450= 1863 KHz 
2). 1485 KHz - 1008 KHz = 450 KHz
Whole MW rang from 522 KHz to 1650 KHz  will have its local Oscillator frequencies Only 2 RF stages will added to the Local Oscillator output for Long range

                                   

                                     

48 V DC to 5 V DC Converter circuit

  High voltage DC conversion to a low level is tough task , but it is not that difficult task so  this circuit is consist of Transistor based DC voltage  down converter circuit , here a power full transistor TIP35C were used , a smal network of resistor 4.7k , 100R 5W , Zener diode 12V, capacitor 220uf were used , Zener Diode first limited the voltages up to 12 from the input with help of TIP35C , a diode IN4001 used for protection to the circuit, this 12V were then applied to any other regulator IC like 7805 or 7809. any other other powerfull transistor be used like 2SC5200.

                                     

DELAY OFF TIMER ( 3vdc to 5vdc )

Some time timer circuits  required for some sort of delay while designing a project  but on a low  voltages we have to design such a special circuits which can even work by taking power from even mobile battery ,the IC 4001 is the best choice for it , even up to 4 timer can be made from one IC package  ( 4 Gates), a very stable & reliable time circuit , using of different values of Capacitor & resistor a different timer  interval can be possible to be made ,  this timer which can work on low voltages like 3vdc to 5 vdc ,this circuit can be used from 12 to 3V dc.