Hay all , Im using a 0.1 Ohms @ 3 watts (wire wound resistor) as a shunt for measuring current of a solar panel...
Its a 10W solar panel.. , Isc=0.7 A and I hope to accurately determine the current as accurately as possible..
Im using an ATmega8 AVR controller , with a 10 bit ADC on it..
As, V=IR,
in my case...
Imax= 1 A (its ~700mA but lets say for simplicity)
Voltage = 0.1 x 0.7 =0.07 V
So, using an op-amp with a gain of 71, gives me .... 0.07 x 71 = 4.97V
I think I would have problems with differentiating such a small signal as lets say I wanted to measure a difference in current of say 5 mA ... I will use an instrumentation amp for better results ... but ..
the question is should I use a larger resistor, so I can measure the current more accurately .. (I know losses would increase but I am willing to trade that for higher current accuracy..)
has anyone ever measured differences in current as small as 1-5 mA ?
Its a 10W solar panel.. , Isc=0.7 A and I hope to accurately determine the current as accurately as possible..
Im using an ATmega8 AVR controller , with a 10 bit ADC on it..
As, V=IR,
in my case...
Imax= 1 A (its ~700mA but lets say for simplicity)
Voltage = 0.1 x 0.7 =0.07 V
So, using an op-amp with a gain of 71, gives me .... 0.07 x 71 = 4.97V
I think I would have problems with differentiating such a small signal as lets say I wanted to measure a difference in current of say 5 mA ... I will use an instrumentation amp for better results ... but ..
the question is should I use a larger resistor, so I can measure the current more accurately .. (I know losses would increase but I am willing to trade that for higher current accuracy..)
has anyone ever measured differences in current as small as 1-5 mA ?