Radio Project Presentation

TECH 1002 Radio Project Assignment Katie Rhodes – P09290071 Joshua Coyne – P09305892 Anthony Gale – P08253822

Introduction Our objective in this assignment is to build a working radio receiver and audio amplifier. Once constructed we will experiment with what AM transmissions our radio can receive.

Equipment Soldering Equipment Circuit Board IC MK484 Transistor BC548B Ferrite Rod & Enamelled Copper Wire Two 100k Resistors, 1K Resistors and one 270R Resistor Slide Switch Two 100nF capacitors, one 10nF capacitor and one 47uF capacitor Headphone Socket AA Battery Holder Soldering Equipment Circuit Board Three 1K resistors, two 470R resistors and one 1R resistor Two 330uF electronic capacitates and one 10uF electrolytic capacitor One 150pF ceramic capacitor One 100nF polyester capacitor and One 47nF polyester capacitor IC TBA 820M One 8 Ohm speaker 100mm of speaker cable One slide switch One 3.5 plug to plug cable One 3.5mm stereo jack socket Components for the Radio Receiver Components for the Audio Amplifier

Method The construction of our radio receiver took place over a course of lab sessions in the University’s Radio Labs

Method An aerial was created consisting of wrapping the enamelled copper wire loosely around the ferrite rod This procedure took time as the wire was required to be wrapped around the rod, with no overlapping, a total of 55 times in order to guarantee the best quality of transmission The next step was the circuit board All the circuit components required soldering into place Smaller components such as the resistors and capacitors were soldered first Next were the BC548B, MK484, radio IC and variable tuning capacitor The larger components such as the aerial, battery hold and headphone socket were then attached

Method The construction of the Audio Amplifier followed a similar process The smaller components such as the resistors and capacitors were soldered first followed by the components like the battery snap, speaker and switch

Testing The radio receiver was first tested using headphone to determine its quality The use of a audio amplifier at this stage could distort the quality of the sound if there were circuit imperfections The first transmission received by our receiver was mainly one of noise and interference By moving the copper wire up and down the ferrite rod however we began to receive a signal from a local radio station

Testing Sabras Radio BBC Asian Network Local station Sabras Radio’s transmission was received. The signal was quite distorted and unclear though BBC’s Asian Network was the other signal we were able to pick up. Once again the signal received was distorted and very difficult to listen to. The quality of both station’s transmissions was worsened when the audio amplifier was attached

Results Explanation The three integral sub-systems which must be working for the radio receiver to be successful are the tuning, demodulation and amplification ones. The testing of our receiver helps us identify any problems with these

Results Explanation The picked up radio station proved the tuning element to be in order Our ability to identify the signals showed the demodulation part to be within working order Interference and distortion on the signal however showed that the MK484 integrated circuit component may not have been soldered correctly Low volume on the output to the headphones means amplification element of our radio wasn’t in full working order The BC548 transistor is a crucial component for the amplification element and the incorrect installation of that could of caused the problems

Results Explanation The poorer quality of the BBC Asian Network signal could be connected to its lower broadcasting frequency Both station’s signals are transmitted from the Freemans Common transmitter in Leicester The differing receptions despite the fact both signals travelled the same amount of distance to where we tested our radio led us to believe there was a difference in the broadcasting frequency BBC Asian Network -837 kHz Sabras Radio – 1260 kHz The higher frequency on the Sabras Radio station explains it being the better of the two signals

AM Transmission Demonstration The aim of this experiment is to show the amplitude modulation of a carrier wave by an audio information signal. The objective is the demonstrate the technique of amplitude modulation used in radio transmissions.

AM Transmission Demonstration Equipment required for this demonstration was an Oscilloscope, a Function Generator, a Wire Aerial and a AM Radio Receiver The wire aerial was connected to the function generator and then into the oscilloscope This allows the signal to be transmitted from the generator but also viewed on the screen on the oscilloscope The carrier wave transmitted by the generator was set to 500Hz and the Modulation wave frequency was 600 kHz. The radio receiver was tuned to this frequency to narrow the amount of signals collect down to our chosen one As soon as the modulation was applied to the carrier wave the monotone sound is demodulated and amplified by the radio receiver.

Explanation of Results The change in waveforms on the oscilloscope shows the technique of the amplitude modulation for radio transmission. This is that the carrier and the modulation wave are merged to transmit information. The carrier wave is stripped away by the receiver’s demodulation and then carries the remaining audio information in the modulation wave to the amplifier.

Conclusion In conclusion the construction and testing of our Am radio should be deemed a success. The circuits and components were all assembled to a level where we were able to receive and identify two transmissions. The poor quality on both of the transmissions means the quality of our output could be improved. This is achieved through taking more care when soldering the circuits and attaching the components.

Photographs Image 1- The soldering process Image 2 - Completed radio circuit board with aerial Image 3 - Radio circuit boad (back view) Image 4 - Ferrite Rod and wire acting as the aerial Image 5&6 - Amplifier circuit board Images 7&8 – Completed amplifier with speaker

Bibliography BBC Asian Network image in slide 8 – http://simplybangra.com/albumcovers/Sept09/bbc_a.jpg Sabras Radio image in slide 8 – http://www.sabrasradio.com/sabras.php DMU logo in slide 4 - http://www.cogain.org/cogain2007/dmu-logo.gif

Radio Project Presentation

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Radio Project Presentation