gaz-sensor/hardware

Hardware

LTSpice simulation

By modifying the R_{cal1} resistor we can see that the maximum output voltage can go up to 5V. The goal would be to modify this resistor value to have a maximum output of around 3.3V:

a=\frac{\Delta{y}}{\Delta{x}}=\frac{y_2-y_1}{x_2-x_1}

AN: a=\frac{10k-1k}{2.1-4.94}

AN: a=-3170

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y=-3170x+b

1000=-3170(4.94)+b

b=3170(4.94)+1000

b=16659

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y=-3170x+16659

We can now calculate the resistor R_{cal1} to have 3.3V in maximum output with the previous formula, we find:

-3.17\times{10^3\times{3.3V}}+16.7\times{10^3}=6.2k\Omega

Has we can see with the LTSpice simulation, we have the correct maximum voltage, it does not go further than 3.29V which is exactly what we wanted.

Electronic CAD