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pheer said:I´m building an automatic measurment system for Grätzel solarcells, it´s supposed to measure voltages between 10mV and 1V with a resolution of 10mV, currents from 1uA to 10mA with 1uA resolution. The range of the load should be approx 1ohm to 10Mohm in say 100 steps (log). All DC. The cost is not a big issue.
I have everything under control except this load issue, the big range is the problem.
pheer said:I´m building an automatic measurment system for Grätzel solarcells, it´s supposed to measure voltages between 10mV and 1V with a resolution of 10mV, currents from 1uA to 10mA with 1uA resolution. The range of the load should be approx 1ohm to 10Mohm in say 100 steps (log). All DC. The cost is not a big issue.
I have everything under control except this load issue, the big range is the problem.
I´m not sure what you mean, do mean by hand changing resistors? It´s supposed to be automated.You could switch resistors in a binary sequence
Figuring out the different values is not a big thing nor very difficult.To cover 7 decades in 100 steps takes approximately 14 steps/decade. In the first decade, you resistor values would be
It sounds like a good idea, but are you sure that it would behave exactly is if it was an ordinary resistor?Would you consider a programmable current source?
I didn't mean to imply that it was difficult. I was only trying to illustrate how close together the resistor values are, bringing up the question (in my mind) of whether you need such fine resolution.Figuring out the different values is not a big thing nor very difficult.
pheer said:I´m not sure what you mean, do mean by hand changing resistors? It´s supposed to be automated.