Friday 23 October 2015

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

                                   

                                     

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Thursday 15 October 2015

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.








                                     


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Tuesday 28 April 2015

Delta Pulse 2 Metal Detector

Any person want a best metal detector he should try to make this detector , but if you want to buy this detector you have to spend to much amount for it , but having a good skill in circuit assembling you can enjoy this versatile detector , i have made this circuit about 5 years ago , and enjoy a lot , in below circuit i have connected LEDs bar, every body worry about coil winding , which is very simple  ,    Below are the two pictures of professional delta pulse 2 metal detector ( Pulse Induction ), where i added LM3914 Ten LEDs BAR graph ,  Perfect and versatile detector. Coil winding for this detector is the critical part , if high gauge wire having  less turns , it will directly damage the FET, if more turns then detector may not work , but i prefer the 26 SWG silver wire to be the best choice for the normal coil diameter coils  with the upto 30 turns , if still have doubt about the number turns of the coil just wind the coil up to 40 turns , just take upto 3 taps after 5 winding, with the best tap selection you can get better result, check result .


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Sunday 22 March 2015

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.




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