ADC = Analog to Digital Converter

An analog input converts a voltage level into a digital value that can be stored and processed in a computer. Why would you want to measure voltages? There are a multitude of sensors available which convert things like temperature, pressure, etc. into voltages.  The voltages can then be easily measured by various kinds of hardware, such as a LabJack U3-HV, and then read into a computer.  The computer can then convert the voltage value into it's original type (temperature, pressure, etc) and the value can then be stored in a file, emailed to someone, or used to control something else outside of the computer.

### Example:

1. Wire the output of the analog temperature sensor to a U3-HV as shown.
2. Read the voltage on the computer to know the current temperature.
3. This particular sensor outputs 0.01 volts per °F, so 0.76V corresponds with 76°F.

### Can we measure standard 4- 20

Can we measure standard 4- 20 mA coming from most field instruments with current transmitter on T7-pro AI channels , as its only mentioned voltags ranges ?

### All our devices have voltage

All our devices have voltage inputs.  To measure 4-20 mA current you simply use a shunt resistor or the LJTick-CurrentShunt.  See the Measuring Current (4-20mA) App Note.

### can I measure low voltage AC

can I measure low voltage AC signals 5-7 Vac

### So perhaps you mean a 60 Hz

So perhaps you mean a 60 Hz sine wave with an RMS voltage of 7?  That means a max of about +9.9 volts and a min of about -9.9 volts.  Yes, you can measure such a signal.  With the U3 or U6 you would use stream mode to grab at least 1 cycle of the waveform, and then do whatever math you desire on it (e.g. RMS calculation).  With the T7 you can do the same, or use the RMS AIN-EF (analog input extended feature) to do all that and just return a single RMS value.