Raj, Lyndsey, Darshil, John

IntroductionThe aim was to create an AM radio and an amplifier from scratch, using various equipment. The reason was to see how an AM radio is constructed, and to see how an amplifier is constructed too. The construction was due to be under way during lab sessions, so before this, it was important to have research done. Each member of the group conducted research and inserted it into a wiki, including images and full references. The research conducted proved to be handy as the group could see what frequency AM radio is, what AM radio needs to work correctly and the difference between AM and FM radio.

AM Radio equipment and apparatus

Equipment Components

Soldering Set Ultra-Miniature slide switch (x1)

Printed Circuit Board Transistor BC548B (x1)

Wire Cutters MK484 Radio IC (x1)

150pF Variable tuning capacitor (x1), 100nF Capacitors (x2), 10nF Capacitor (x1), 47uF capacitor (x1)

100mm Ferrite Rod (x1)

2.5m of 0.315mm enamelled copper wire

100K Resistors (x2), 270R Resistor (x1), 1K Resistors (x2)

Headphone socket (x1)

AA Battery holder (x1)

Radio Construction The construction of the radio begins by simply wrapping the coil of enamelled

copper wire around the ferrite rod around fifty five times. Before the winding is begun, attach the wire to the rod with insulating tape, leaving approximately 100mm for attachment purposes. Then begin winding the coils TIGHTLY around the ferrite. Once this is done, secure the end with another strip of insulating tape.

The next step requires that all of the individual components themselves are soldered into their correct places; an effort aided by the use of numbers on the components themselves that relate to designated positions on the circuit board. The wires used to connect the aerial, headphones and battery were stripped in preparation for soldering and, following this attachment, all of the excess metal on the components was trimmed down to make areas more accessible.

The process did not, however, run one hundred percent smoothly: There was a period of time where the negative headphone wire simply refused to solder, and the thick green wire chosen to connect key components was too big to fit into its place on the board. These issues were quickly resolved, however, and the construction stage, completed.

Radio ResultsThe finished product was then given an AA battery and

connected to an amplifier to see if it was working. Upon testing the newly-completed AM radio, it was discovered that the equipment worked rather well indeed, picking up two radio stations; Sabras Radio and BBC Asian Network.

This happens when the signal is picked up by the aerial and responded to by changing the tuning circuit to a particular frequency, which in turn ensures that all other frequencies are ignored in favour of the one chosen. The signal is then demodulated, removing the original sound from its carrier waves, before being amplified and played out via a speaker so that the listener may hear the sound more clearly.

Equipment and ApparatusEquipment Components

Soldering Set IC TBA 820M chip

Printed Circuit Board 1K resistors (x3), 470R resistors (x2), 1R resistor (x1)

Wire Cutters330uF electrolytic capacitor (x2), 10uF electrolytic, 150pF ceramic, 100nF polyester, 47nF polyester

8 Ohm speaker

3.5mm plug to plug cable

100mm of speaker cable

a slide switch

PP3 battery snap

3.5mm stereo jack socket

Amp equipment and apparatus

Amp ConstructionIn week ten the group soldered various components for example the

resistors and capacitors, all the group took turns and had a chance to solder Also the group got familiar with the rest of the parts as to were they go on the print circuit board and how.

Week eleven was a continuation of the soldering, the rest of the components that remained which were the larger components were then soldered. These parts included the speaker, which the group had to define were the positive and negative areas were. The 3.5mm socket was then soldered to the print circuit board, fallowed by the LED and then the IC socket. The last thing that the group did was place the TBA820M chip into the IC socket.

Finally all the components were soldered and placed into position, the only thing remaining was to connect the radio and battery and begin to test. Using the battery, cord and radio, the amplifier was tested.

Amp ResultsAfter completion of the amplifier the testing was then done.

The test showed success as the amplifier gave out the music from a radio signal. However the amplifier had to be moved from position to position to make the sound come out properly.

After the results showed the amplifier to be working, the group then tried the amplifier on an Ipod to see how if and how the amplifier would handle mp3 quality music. The amplifier played the music off the Ipod successfully with one miner being that one of the wires was loose and had to be moved slightly but nothing else serious. This was easily fixed by soldering the wire again to make it sturdier.

ConclusionIn conclusion the radio and the amplifier both turned out successful

with minor setbacks which were resolved.This could be attributed to efficient and supportive team work,

dedication to the task, and constant motivation towards the objective.

Each group member contributed using their own skills and because each member brought something different, this enabled a good contrast of ideas and methods.

Improvements could be focused around insuring all team members are efficient with soldering equipment to help speed up the process. Otherwise the project flowed seamlessly.

The project could be further extended by possibly constructing an FM radio and cases to hold both present and future technologies.