Week 2 Activity

Part 1: Build Integrator Circuit

This week we continued to build the integrator circuit because last week our circuit existed problems. The following is the circuit we design and the real circuit we built. The input voltage is a 50kHz square wave. R3=10k ohm, R=10k ohm and we changed the value of capacitance and resistance. 

At first, we found no matter we changed the capacitance or resistance, the output waveform kept unchanged. We checked our circuit, input signal and the set of digital oscilloscope but found no error that lead to the wrong output. We spent a lot time in checking mistakes and finally we found that we forgot to provide a DC input voltage to active the amplifier. We provide a 5V DC input voltage, then the circuit worked normally.

First, we set Rc=330k ohm and C=10nF. 

Part 2: Problems in Output Waveform 

We kept Rc=330k ohm unchanged, then changed the value of capacitor from 10nFto 0.2μF. We found that the big change of capacitance had very slightly influence on the output waveform shape. Next, we kept C=10nF unchanged, and changed the value of Rc from 330k ohm to 10k ohm. We found that the change of resistance had big influence on the waveform. 

This phenomenon didn’t accord with theoretical value. We expected that the change of capacitance will influence the output waveform shape and the resistance won’t disturb the output. We spent a lot time in trying to work out the reason but got no result.

Part 3:  Current Transducer and Summary

The model type of current transducer was LA 25-P. We searched this type online and found the instruction book of it. Then we learned it properties and how to use it in the circuit. Then we didn’t have enough time so we finished this week activities.

In summary, this week we leant how to use current transducer and still working on integrator circuit. We found the problems on the output waveform but didn’t work out the reason for the error.

Part 4: Objectives of Next Week

For next week, we plan to find the reason why the change of capacitance and Rc has opposite influence on output waveform with expected value. After we find the reason and error, we will finish to build the integrator circuit.

Second, we will find how to use power amplifier. 

If we have enough time, we will try to wind the coil and connect amplifier circuit and integrator circuit together.

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Week 1 Activities

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Week 5 Activity

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Week 4 Activity

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Part 1: Power Amplifier Circuit First we built power amplifier circuit. According to the instruction book, we knew we need to used two 1000 μF capacitors connected with power amplifier. Then we inserted a resistor to measure the output signal. According to the instruction book of power amplifier, it requires a symmetric DC power supply with an output range of 30 to 35V. In the experiment we provided a 30V DC power supply.  After testing the power amplifier circuit, we put current transducer into the circuit but the result was incorrect. We decided to finish this part in next week. Part 2: Theoretical voltage of coil We estimated the ratio of number of turns to length 1cm. The estimated result is 21 turns per centimeter, so N/L=2100 (turns per meter). Then we measured the coil diameter by electronic digital caliper is 2.4mm so r=1.2mm. In the experiment, the signal frequency we used was 50kHz. The calculation of coil theoretical voltage is following: ...
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