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Analog sensors (water level, temmperature, pressure etc.)

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howie

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analogue sensing for water level

I am designing a data logger that utilizes differential analog inputs for analog sensors. Most of the applications will be used in liquid level, temperature and pressure sensing and logging. Most of analog sensors have analog voltage outputs ranging between 0-5Vac but some have current outputs from 0-40mA.

The problem is that the ADC chip that I use to convert analog to digital can only measure voltage levels. Can someone suggest an 8bit, 8 channel and above ADC chip that can both measure current and voltage. If possible, the chip can be interfaced to a processor through SPI to minimize General Purpose I/O pins on the processor that I am using.
 

analog sensor to measure voltage

Hello!

Here is some basic **broken link removed** about what you can do with op amps.
I would advice to consider the current / voltage converter so that you can
measure currents with a regular ADC. Anyway I don't know any device
that directly measures currents.

Then instead of a 8-bit, 8-channel ADC, you may also consider a processor
with integrated ADC.
One example would be MSP430 (there are many others, but I like this one
for low power applications). For instance MSP430F147 has 8-channels
12-bit converter. It is possible to configure it in 8-bit so it's a little bit faster.

Have fun!

Dora


howie said:
I am designing a data logger that utilizes differential analog inputs for analog sensors. Most of the applications will be used in liquid level, temperature and pressure sensing and logging. Most of analog sensors have analog voltage outputs ranging between 0-5Vac but some have current outputs from 0-40mA.

The problem is that the ADC chip that I use to convert analog to digital can only measure voltage levels. Can someone suggest an 8bit, 8 channel and above ADC chip that can both measure current and voltage. If possible, the chip can be interfaced to a processor through SPI to minimize General Purpose I/O pins on the processor that I am using.
Click to expand...
 

water level analog

Hi howie,

According to my experience, there is no normal ADCs that is able to measure current and voltage in the market. You may need the ICs that is able to convert to the voltage from the current first, and then measure the needed voltages with ADCs.

By the way, it's easy to find the ICs ICs that is able to convert to the voltage from the current.

Best regards,
Evan
 

information on analogue sensors

Hi!
What are:
* the needed accuracy ?
* frequency band?
* input protection?
* temperature range?
* type of sensors? (exact types?)
* input resistance?
* working temperature interval?
Etc.
Current to voltage converter could an accurate resistor, e.g. with tolerance +-0.1% or better.
BR
 

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