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Usage of a Voltage Divider (A /D input)

Q: Is it possible to monitor an external voltage or the Data Logger Sensor Power?

A: You can add an “automatic sensor power monitor”, that appears in the Data Log file.

It will monitor if Sensor Power is available during the measurement cycle.

C: The input voltage on an analog port is limited to 10V. Use a voltage divider and supply the output to an analog input port.

– A free analog port on a ML-x17 data logger (choose input voltage) or ML-OI-AD-10V option board.

– Two resistors (10k).

– If only check for Sensor Power available, a digital input port can be used.

Formula: V out = V in  * (R2 /(R1 + R2))

Analog (and digital) input ports are limited to 10 Volt.

U = top line connected to 12V sensor power, bottom line connected to Gnd.

U2 = divider output.

(Use a warm-up time on the analog input port).

Top wire = battery power positive (U)

Bottom wire = Data Logger GND and battery negative.

Middle wire: divided voltage (U2) connect this wire to the available analog port. With two equal resistors, readings on this port will show 1/2 input (battery) voltage. Use the min-max calibration to get the correct value or use a Derivered Channel to multiply the reading by 2 to get the actual battery voltage.

Please read the sections 4.11 and 4.35.2 from the manual: 


​Be aware the voltage divider is consuming power: 12V /20k = 0,6 mA –> 0,72 mWatt, add this to the power calculations, if you use the Data Logger power..

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