ELECTRONICS EXPERIMENTS
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THE PHYSICS SUPERMARKET
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IEC Electronics Board
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This electronics board has been designed to take the beginner electronics student through a series of experiments
all aiming to develop the knowledge needed to understand how music can be transmitted down an optical fibe using
amplitude modulated light - an amazing effect! The board is supplied with the CD of student worksheets written in Word
which teachers are free to photocopy and give to their students.
For information about the Electronics Board Contact IEC 61 McClure St Thornbury 3071 Melbourne Australia
Tel 61 3 9497 2555 fax 61 3 9497 2166 email iec@iecpl.com.au
1. Potential Dividers Part 1
Students build potential divers firstly using two light globes and then using two resistors. They learn how to
calculate the value of the output potential using the potential of the supply and the values of the two resistors.
Students investigate changing the relative sizes of the two resistors and how it alters the size of the output.
IEC Electronics Board, voltmeter
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2. Characteristics of Components
Students investigate the behaviour of a selection of components which includes a diode, an LED, an LDR, a thermistor, and a photodiode.
The characteristic curves of the diode and the LED are drawn and a graph of resistance versus temperature is drawn for the thermistor.
The photodiode is investigated in normal mode, reverse bias mode and photovoltaic mode.
IEC Electronics Board, thermometer, voltmeter, ammeter Top
3. Potential dividers Part 2
Students build potential dividers that include the LDR and the photodiode in reverse bias mode. Students investigate the response time
of the two to changes in light intensity at their surfaces.
IEC Electronics Board, CRO, Signal Generator Top
4. Capacitors (Charge and Discharge)
Students investigate the charging and discharging of capacitors using various combinations of R and C. They combine
AC and DC siganls and discover the capacitor can pass the AC component but not the DC component.
IEC Electronics Board, CRO, Signal Generator, 1.5 V cell Top
5. Capacitors (Couplers)
Students investigate the use of a capacitor to couple a signal generator to a potential divider so the DC potential of its output is not
affected by the presence of the signal generator. Also, the factors that influence the opposition of the capacitor to the passing of an AC signal are investigated.
IEC Electronics Board, CRO, Signal Generator, AC voltmeter Top
6. Basic Transistor Amplifier
Students undertake a complete investigation into the behavior of the common emitter npn one transistor amplifier.
Setting the operating point, current and voltage amplification are studied.
IEC Electronics Board, CRO, Signal generator, audio amplifier, 2 voltmeters, 0-50 microammeter, 0-5 milliammeter.
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7. Advanced Transistor Amplifier
Students investigate thermal runaway and learn how to minimize its affects with the inclusion of an emitter resistor and a bypass
capacitor.
IEC Electronics Board, CRO, Signal Generator, Hair Dryer, pliers, voltmeter. Top
8. Circuit Design
Students create a simple circuit to turn on an LED when the light level drops below a prescribed value.
IEC Electronics Board, Analogue to Digital Interface, notebook computer, light sensor.
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9. Opto-Electrical Convertor
This experiment is the last in the series. All of the previous experiments have been designed for the students to gain the
knowledge needed to understand what they construct in this experiment. They pass down an optical fibre light that has been amplitude
modulated by the headphone output of a CD player. The light is aimed at a phototransistor, a photo diode and an LDR in potential
dividers. The output of the potential divider is fed into a transistor amplifier via a coupling capacitor. The output of the amplifier
is fed to an audio amplifier. If you have never done this or seen it done before, you will be amazed at the quality of
the music that is transmitted! Students compare the timbre of the sound created by the phototransistor, the photodiode and the LDR
and relate it to what they discovered earlier about the response time of the components.
IEC Electronics Board, CD player, audio amplifier Top