Tech Note 267 Detail

Adapting existing Power Amplifier experiments to work with the ScienceWorkshop 750 Interface?

Affected Products:

CI-7565 ScienceWorkshop 750 Interface

Problem/Symptom:
How do I adapt the ScienceWorkshop 750 Interface to work with the existing Power Amplifier experiments in my ScienceWorkshop Physics, Chemistry and Biology Teacher's Guide?

PASCO Solution:
NOTE: With ScienceWorkshop version 2.3.1 or later, all saved files from previous versions of SW using the Power Amplifier will open with the voltage set in the Signal Generator window at half the value that was originally saved. If you save an experiment with version 2.3.1 or later the voltage will be correctly set when you reopen the file.

NOTE: For all experiments which require the use of a Wave Driver (exp. P20, P31) it is recommended that the SF-9324 be used over the WA-9753. The SF-9324 requires less power to operate when compared to the WA-9753.

In all Experiment Library Experiments, the Power Amplifier icon should be deselected from the Experiment Setup window.

P20: Driven Harmonic Motion
P24: Motor / Generator Efficiency
P31: Waves on a String
P32: Sound Waves
P34: Sonometer
P35: Resonant Modes of a Tube
P36: Speed of Sound
P39: Electrical Equivalent of Heat
P40: Ohm’s Law
P42: Transformer
P43: RC Circuit
P44: LR Circuit
P45: LRC Circuit
P46: Diodes Lab 1 - Properties & LED’s
P47: Diodes Lab 2 - Rectifier & Power Supply
P48: Transistor Lab 1
P49: Transistor Lab 2
P50: Transistor Lab 3
P52: Magnetic Field of a Solenoid
P53: Magnetic Field of Helmholtz Coils
B15: Reaction Time
C29: Electroplating

P20: Driven Harmonic Motion

P20 can be performed with the 750 Interface. However, the Wave Driver will require more power than the 750 can provide. This results in a distorted waveform for most voltages. This is OK for this particular experiment. The user will find that the experiment will work significantly better if the Power Amplifier (CI-6552A) is used, as the amplitude of the Wave Driver displacement is increased. Therefore, the CI-6552A is recommended for this experiment.


Experiment P20 run with (green) and without (purple) the CI-6552A Power Amplifier. Increase in oscillation amplitude is greatly enhanced with the use of the Power Amplifier.

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P24: Motor / Generator Efficiency

P24 cannot be performed with the 750 Interface. One section of the lab does not require a power amplifier, so it can be performed. The other section requires more power than can be supplied by the 750. The Power Amplifier must be used.

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P31: Waves on a String

Portions of P31 can be performed with the 750 interface. Part A, where the tension on the string is varied, can be performed with the Waveform Amplitude set to 5.0 V or slightly less and the Frequency set to approximately 60 Hz. Part B, where the Frequency is varied, can be performed until approximately the third or fourth harmonic frequency. The current output should be monitored, and the voltage should be decreased to prevent waveform distortion. Further harmonic frequencies are difficult to detect, as the amplitude must be greatly decreased to the point where nodes are hard to distinguish.

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P32: Sound Waves

P32 can be performed with the 750 interface without further modification. Note that P32 is set to use the older Sound Sensors. For the CI-6506B Sound Sensor, the Sensitivity should be reduced to Low and the Oscilloscope display should also be adjusted so that Channel A is at 0.5 or 1V/div.

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P34: Sonometer

P34 can be performed with the 750. Depending on the driving frequency, the voltage will have to be adjusted so that the waveform output is not distorted. Monitor the Current output and adjust the Wave Amplitude until the output waveform is not distorted. When the resonant frequency is found, the detector output should be sufficient so that the nodes and antinodes on the string can be detected.

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P35: Resonant Modes of a Tube

P35 can be performed with the 750 without further modification to the experiment. Note that in P35 the Sensitivity of Channel A is set to Low. Change the Sensitivity to High for the best results.

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P36: Speed of Sound

P36 can be performed with the 750 without further modification to the experiment. Note that in P36 the Sensitivity of Channel A is set to Low. Change the Sensitivity to High for the best results.

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P39: Electrical Equivalent of Heat

P39 cannot be performed with the 750. The experiment requires more power than can be supplied by the 750.

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P40: Ohm’s Law

P40 can be performed with the 750. In addition to deleting the Power Amplifier icon from the Experiment Setup Window, click on the "Sample I" button. The oscilloscope X axis Input must now be changed to Output Current. NOTE: The Oscilloscope Display, the current output is scaled so that a reading of 1 volt = 50 mA output current. This must be accounted for especially when you determine the resistors’ value by calculating the slope of the V vs. I line.

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P42: Transformer

P40 can be performed with the 750. You must change the voltages from what is described in the manual. Change the voltage in part A from 0.2 V to 0.1 V. Too much current will be required if the voltage is kept at 0.2 V ( for the coreless transformer portion). The voltage in part B should also be changed from 2.0 V to 1.0 V so that the voltage ratio is preserved from the first part to the second part of the experiment. Lowering the voltages will also lower the resultant output signal. For part b, the signal is so small, that the Sensitivity on Channel B should be changed from Low to Medium (or High).

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P43: RC Circuit

P43 can be performed with the 750 without further modification to the experiment.

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P44: LR Circuit

P44 can be performed with the 750. In addition to deleting the Power Amplifier icon from the Experiment Setup Window, click on the "Sample I" button. For the Graph Display, change the Y-axis Input for the lower most graph from Channel C (Power Amp.) to Analog Output. Change the Start Condition From Analog C, 0V, / Rises, to Analog Output, 0V, \ Falls.

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P45: LRC Circuit

P45 can be performed with the 750 without further modification to the experiment.

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P46: Diodes Lab 1 - Properties & LED’s

P46 can be performed with the 750. The Waveform Amplitude must be decreased to 5 V. Change the Start Condition from Analog Output, -5.0 V, / Rises, to Analog Output, - 4.8 V, / Rises. Change the Stop Condition from Sample for 250 samples to Sample for 240 samples.

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P47: Diodes Lab 2 - Rectifier & Power Supply

P47 can be performed with the 750. The Waveform Amplitude was set to 6V, thus when using 2.3.1, the Amplitude will be set at startup as 3.0V. This is a good voltage to perform the first part of the experiment, so keep the Amplitude set at 3.0 V. You must change the input for Channel 1 of the Oscilloscope Display from Analog Output to Analog A. Change the Sweep Speed on the Oscilloscope Display from 50 ms/div to 100 ms/div. NOTE: the instructions (in the first section) state to use the Pause button to freeze the Oscilloscope Display to enable the use of the Data Cache feature. You must use the Stop button to enable the use of the Data Cache feature. In Part III A, Analyzing the data, the plots should be scaled to 3.5 V Max., -3.5 V Min. to reflect the lower voltages which are used.

For Unit Four - Power Supply, Single Diode and Four Diode Bridge, decrease the Waveform Amplitude to 2.0 V or else the power output capacity of the 750 will be exceeded and waveform distortion will occur for part of the experiment.

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P48: Transistor Lab 1

P48 can be performed with the 750 without further modification to the experiment. Optionally you can set the Waveform Amplitude to 2.0 V so that the LED is slightly more visible.

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P49: Transistor Lab 2

P49 can be performed with the 750 without further modification to the experiment. Note that there is a misprint on the circuit diagram for this experiment. Channel A and Channel B should be switched. The actual instructions and the picture of the connections on the AC/DC Electronics Laboratory board are correct.

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P50: Transistor Lab 3

P49 can be performed with the 750 without further modification to the experiment. When deleting the Power Amplifier icon in the Experiment Setup window, also delete the Voltage Sensor icon on Channel B, as it is not necessary.

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P52: Magnetic Field of a Solenoid

P52 can be performed with the 750. In addition to deleting the Power Amplifier icon from the Experiment Setup Window, click on the "Sample I" button. Set the DC Voltage to 5.00 V. Change the input for the Digits window which is set for Channel B to "Output Current". The intensity of the magnetic field in the solenoid will be less than if you were using the CI-6552A Power Amplifier, so if possible run this experiment using the Power Amplifier.


Experiment P52 run with (green) and without (red) the CI-6552A Power Amplifier. Magnetic field strength is greatly enhanced with the use of the Power Amplifier.

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P53: Magnetic Field of Helmholtz Coils

P53 can be performed with the 750. In addition to deleting the Power Amplifier icon from the Experiment Setup Window, click on the "Sample I" button. Set the DC Voltage to 5.00 V. Change the input for the Digits window which is set for Channel B to "Output Current." At 5.0V, the Helmholtz Coils will require more power than the 750 can provide. The current will be limited at 300 mA, which will hold the voltage to about 3.5 volts. The experiment will still work, however as in the previous experiment the intensity of the magnetic field within the Helmholtz coils will be less than if you were using the CI-6552A Power Amplifier, so if possible run this experiment using the Power Amplifier.

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B15: Reaction Time

B15 can be performed with the 750. NOTE: Users with ScienceWorkshop program version 2.3.1 will need to get a special ROM patch for the 750 from Technical Support in order for this experiment to function properly.

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C29: Electroplating

C29 can be performed with the 750. Set the DC voltage to 5.0 V. At this voltage, the experifment will require more power than the 750 can provide. The current will be limited at 300 mA, which will hold the voltage around 1 to 2 V. The amount of copper oxidized will be less than if this experiment were performed with the CI-6552A Power Amplifier. The results will be less accurate, though should produce results which are within 5% of accepted values. It is recommended that the CI-6552A Power Amplifier should be used for this experiment.

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Creation Date: 01/1/2000
Last Modified: 10/16/2001
Mod Summary: