Arduino | Industrial Automation Blogsphere

Pressure Sensor

February 22nd, 2010 admin No comments

Pressure Sensor

Pressure Sensor?

I have ordered a wrong sensor. Instead of 20Kpa sensor i have ordered 500Kpa sensor. my project is due in a week and i have no time to order the next sensor. How do i do the modification of the 500kpa sensor. something have to be done to the input analog volatge....

All things being equal, it sounds like you will be getting an output from your sensor that is 1/25 the amplitude that you were expecting. You can use an op-amp to increase the gain of the sensor, but it will be much noisier than the appropriately scaled sensor would be.

That said, I am assuming your sensor has a high impedance output in the millivolt range. Selection of the op-amp may be a moot point since if you don't have time to get the right sensor, you will likely also have to settle on whatever opamp you have on hand. But if you have a high impedance low noise amplifier, that would be a good choice. Most of the pressure sensors require a load impadance greater than 1 Mohm.

So, using your op-amp in a non-inverting mode, you would connect the sensor to the non-inverting pin (+) and place a feedback resistor (Rf) between the output of the opamp and the inverting input of the opamp. Then another resistor (Rs) between the inverting pin and ground. The values of the resistors are not too critical, except that the ratio of Rf to Rs should be 24:1. I would try 24.3k and 1k. Now to balance out the inputs, you should really put a 1k resistor between the sensor and the non-inverting input. Power the op-amp with an adequate supply and you should have a converted sensor.

If your opamp selection is also a rail-to-rail opamp, you can power the opamp off the same supply you use for the sensor.

For a super low-noise solution, try an instrumentation amplifier. These guys have minimum offset and the gain is set by a single external resistor.

Good luck.

Multipoint Temperature Profilers meet needs of process applications.
Intended for chemical reactors and desulphurisation catalyst bed reactors, AerOradial multipoint temperature assemblies offer maximum number of temperature measurement points through single process connection or entry nozzle. AerOpak mineral insulated cables, offering single-tip measurement or multiple sensing points within single stem, enable full, 3D temperature profiling for safe control of ...