Setup circuit for current sensing. Using conventional current sensing method, sense resistor, Rs (0.3 ohm, 20W) is placed in series with the current path that has been measured. The circuit is designed to have maximum 5A current to flow through load. For 0.8A current, the voltage across sense resistor is 0.233V(almost 0.24V) . The ohms law 0.8A*0.3 ohm = 0.24 V. The voltage is multiplied using an amplifier circuit (gain = 3.33) so that 0.78V is achieved. This 0.78V is fed into ADC of PIC microcontroller for calculation.
For 1V ADC voltage, the PIC converts to be 1A in real current.
Using PIC microcontroller, solar voltage at 12.9V and solar output current at 0.1A is displayed via blue LCD. 140 and 7 are the variables set inside the programming code.
Close view for circuit setup.
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