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The Challenge: Make a Transmitter and Receiver



How is a transformer made?

The transformer is made up of two coils of wire (a primary and a secondary coil) wound around each other, usually on a metal former to make it more efficient. How much a transformer will change the voltage depends on the ratio of the number of turns of wire in the two coils. If both sets of coils have the same number of turns then the voltage and current that go in will be the same as the voltage and current that go out. If the secondary coil has 100 times the number turns as the primary coil, then the transformer will in principle step up the voltage by 100 times. In reality, the efficiency is somewhat lower due to heat loss.

However, a transformer will not work with the direct current (DC) from a battery — it will only work with an alternating current (AC - one that changes constantly).

To convert the DC voltage of the battery from DC to AC we built a buzzer. This is a device that constantly interrupts the direct current flowing and produces a crude AC current. This current was then fed to the transformer which boosted the voltage, producing a much bigger spark.

DC graph