I would like to measure the pressure with a sensor : MPXV7007 (see link below).
By chance, the supply voltage is 5V, so I can supply it with the 5V pin of the Arduino.
But the supply current is 7mAdc (10mAdc at maximum). And the Arduino seems to deliver 50mAdc. So apparently it won't be fine.
I know that I could reduce the current with a resistor. So if I put a resistor between the 5V output of the Arduino and the input of the sensor I could be right?
These are my maths : If I1 is the 50mA from the Arduino and 7mA the current input in the sensor, I have :
R = U / (I1 - I2) = 5 / (50 - 7 ) . 10^-3 = 120 Ohms
Connect the ground, the 5V and the output of the sensor to an analog input of the Arduino. That's all.
That is however not a sensor for liquids, it is for air pressure.
The used current of 7mA or 10mA can be supplied by the Arduino, don't worry about it.
A car battery of 12V can supply 100A. But a car radio of 12V needs only 1A.
The mains in your house can supply perhaps 16A. But a light bulb of 0.5A will be fine.
A device requires a certain amount of current, and as long as the power supply can do that, everything is fine.
I want to measure the pressure inside a fluid which is at rest (pressure between 0 and 10kPa).
And a guy told me to pay attention to the frequency and that it should be close to DC because my media is not "vibrating". But I can't find any information about that in the datasheet. I never heard that and I didn't find anything on Google.
Do you think it is a parameter I should verify or my sensor should be good?
The frequency ? I don't know what that guy was talking about.
Most of those Freescale sensors are all alike. You can not drop them in the water to measure the pressure.
In the datasheet of the MPVZ5010G, a "Reference AN1950" is mentioned for washing machine water level.
When you search for AN1950, you find a drawing in that Application Note with a tube and the sensor on the top.
So that sensor is never in the water.
When you want to drop a sensor in the water to measure the pressure, you need a complete device that has a sensor inside. Search for it with some of these words: submersible depth sensor pressure tranducer water level
I actually want to measure the pressure inside a tube which would be connected to the port of the transducer.
I finally found one that allows a liquid media. I called a salesman from the company and it seems to be perfect for me.
I remember that in my classes, we never put capacitors like in the schematics showing the electrical connections. Should I connect capacitors like indicated ? I think it will filter the signal... I don't understand that very well.
And the PIN named "C" is actually just connected to the ground?
That one allows liquids (but not all liquids).
You should do exactly as in the schematic.
The 10nF to Vout is to filter the signal, it seems to be needed to make the sensor work better. And 10nF is only very small.
The 'C' is connected with a capacitor of 100nF to ground. That is probably something internal that requires a capacitor. There are many more chips that use a pin to be connected to a capacitor. So don't connect pin 'C' to ground, use the capacitor as in the schematic.