Carolina® AM Crystal Radio Kit | Carolina.com

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Carolina® AM Crystal Radio Kit

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Grades 9–12. In this activity, student teams construct working AM crystal radios, learning how modern communication systems transmit information using electromagnetic radiation by modulating waves to encode a signal. Includes a battery-powered speaker (with internal rechargeable battery) that amplifies the audio output for testing and listening. Kit contains materials to build 10 crystal radios and is designed for a class of 30 students.

 
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Grades 9–12. Using kit materials, students construct a working AM crystal radio, popular in the early days of broadcasting, to tune into local stations. They build circuit components such as a variable capacitor and variable inductor from aluminum foil, copper wire, and cardboard tubes. In this activity, students learn how modern communication systems transmit information using electromagnetic radiation by modulating waves to encode a signal. Students learn how communication systems modulate signals using wave properties like amplitude, frequency, and the wave equation to embed signals in the carrier wave. In addition, students learn how each component functions in modulation and demodulation. A battery-powered speaker (with internal rechargeable battery) is included to amplify the audio output for testing and listening.

During the activity, students observe energy conversion between different forms (e.g., electrical energy to mechanical energy) and learn how a modern germanium diode functions as the radio's crystal to demodulate the signal. Students build upon their knowledge of wave properties by learning:

  • How transducers convert the signal's electrical energy into a mechanical sound wave, a direct analog of the original signal.
  • The relationships between inductance, capacitance, and resonance in tuning to a radio station and building the classic tank circuit, LC (inductor-capacitor).

The crosscutting concept of structure and function is addressed by students learning how the geometrical properties of the constructed capacitor and inductor affect inductance, capacitance, and tuning frequency. Designed for a class of 30 students, the kit contains materials to construct 10 functioning crystal radios and includes free 1-year access to digital resources that support 3-dimensional instruction for NGSS. A high-impedance piezoelectric earphone (item #754012), similar to the ones used with WWII-era foxhole radios, can be purchased separately. It, too, is powered solely by radio waves.

This kit builds toward the following Performance Expectations within the NGSS (Next Generation Science Standards*): Waves and Their Applications in Technologies for Information Transfer, HS-PS4-5 and HS-PS4-3; and Energy, HS-PS3-3.

The Carolina® AM Crystal Radio Kit is designed to integrate into a larger unit with lessons addressing wave mechanics, electricity, magnetism, and electromagnetism.

*Next Generation Science Standards® (NGSS) is a registered trademark of Achieve. Neither Achieve nor the lead states and partners that developed the Next Generation Science Standards were involved in the production of, and do not endorse, these products.

 
 
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