Task 1: Voltage Divider Circuit
As most of our sensors and controllers operate on 5 volts or less, we would require a voltage divider circuit in order to ensure that there is 5 volts to operate the necessary circuits.
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| Figure 1. Voltage Divider Circuit |
The principle of a voltage divider is shown in the circuit above. Using 2 resistors, the voltage measured by the voltmeter at the particular point will be just a fraction of the original voltage. The output voltage is directly proportional to the source as well as the ratio of the resistors used in the design. In Sunspec 4, we will be designing our own circuit using the same principle to achieve a low voltage from a high voltage.
Task 2: Optocoupler Circuit
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| Figure 2. Voltage Isolation Circuit using Optocoupler |
Due to the fact that we are dealing with high voltages, there is a high chance of compromising the user's safety as well as damaging components used in the telemetry system. Therefore, a voltage isolation circuit is required. An optocoupler circuit is used to allow this to happen. For this circuit, the input voltage will be proportional to the output voltage. The larger the input voltage(1 and 2) , the brighter the LED in the circuit, the more light detected, the higher the output at the end of the circuit(3 and 4).
Task 3: Differential Amplifier
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| Figure 3. Differential Amplifier |
This circuit is used to obtain more accurate readings for our uni-directional sensors. For a bidirectional sensor, a base voltage of 2.5V is inputted so that it raises the measuring range from 0V to 2.5V out of 5V. 0 to 2.5V is used for negative flow of the current detected by the sensor. Since unidirectional sensors only sense one sided flow of current, the range of measurement is limited to 2.5 to 5V, which decreases our accuracy in readings.( Possibility of voltage less than 2.5V). Input voltage from the sensor will be inputted into one of the inputs while the other one will be kept at 2.5V to offset the rise in range caused by the design of the sensor.
