CMA Current Sensor User guide

CURRENTSENSORML23F

SER

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S

UIDE



CENTRE FOR MICROCOMPUTER APPLICATIONS

http://www.cma-science.nl

2|ML23fCurrentSensorUser’sGuide

Shortdescription

TheCurrentsensorML23fisageneral‐purposesensortomeasurecurrentsinACand

DC circuits in the range between‐12.5 and +12.5 mA. The sensor is equipped with

two 4‐mm banana plugs and two additional alligator clips are delivered with the

sensor.

The Current sensor should be placed

 in series with the circuit component through

whichthecurrentismeasured. Currentsineitherdirectioncanbemeasured.

TheCurrentsensorhasaverylowresistancesothatitintroducesaslittleresistance

aspossibletothecircuit.Thesensorisprotectedandcurrentsupto25mAwill 

not

damagethesensorbutitnevershouldbeusedforhighercurrents.

The Current sensor is an I2C digital sensor, which gives calibrated values of the

measured quantity. This sensor can only be connected to special interfaces that

supportI2C digitalsensorsliketheCMA MoLab interface.The sensorcable

needed

toconnectthesensortoaninterfaceisnotsuppliedwiththesensor(sensorcables

aresuppliedwithinterfaces).

Sensorspecifications

Forsamplingratesup1kHz(1000samplespersecond)theCurrentsensorworksasa

digitalsensorandconvertsthemeasuredcurrenttoadigitalvaluevia14‐bitanalog‐

to‐digitalconversion.Forsamplingratesabove1kHzthesensorworksasananalog

sensor. An analog signal generated

 by the sensor (on its ADC pin) is read by the

connectedinterfaceandisconvertedtoadigitalvaluebythe12‐bitADconverteron

the interface. The maximum  sampling rate of the sensor is 100 kHz (samples per

second).

Practicalinformation



CAUTION:

 NEVERconnectaCurrentsensordirectlyacrossabatteryorpowersupply,

withoutaresistancecomponenttolimitthecurrentwithintherangeofthe

sensor.Failuretolimitthecurrentwillcausepermanentdamagetothesensor.

 NEVERusehighvoltagesorhouseholdAC.

 TheCurrentsensorshouldbeplacedinserieswiththecircuitcomponentthrough

whichthecurrentisto bemeasured.

 Makesureyouobservethecorrectpolarityi.e.connecttheblackleadfromthe

CurrentSensortothenegativeterminalofthecells,otherwisethesensorwillgive

readings

withthewrongsign.

ML23fCurrentSensorUser’sGuide| 3

 Currentsineitherdirectioncanbemeasured.

Collectingdata

This Current sensor works only with specific interfaces. The sensor will be

automatically detected when connected to such  an interface. For detailed

information about measurements with sensors consult the User Manuals of  the

interfaceandtheCoach6software.

Calibration

The Current sensor is s upplied with factory calibration in ampere (A). The Coach 6 

program allows shifting the pre‐define d calibration or creating a new two‐points

linearcalibrationifneeded.Theusercalibrationisstoredinnon‐volatileusersensor

memory.

Suggestedexperiments

ThisCurrentsensorcanbeusedinvariousexperimentssuchas:

 Characteristicsofalightbulbandadiode.

 MeasurementsofinternalresonanceandEMF.

 Measurementsinseriesandparallelelectricalcircuits.

 Together with a Voltage sensor it can be used to explore the relationship

betweenthe

currentandthevoltageinelectricalcircuits.



Figure2.ConnectingtheCurrentsensor

inserieswitharesistortomeasurethe

currentpassingthroughit.

Figure2. MeasuringthecurrentpassingthroughaLED.

4|ML23fCurrentSensorUser’sGuide

TechnicalSpecifications



Sensorkind Upto1000Hz‐digital

(on‐sensoranalogtodigitalconversion)

(14‐bitsresolution,communicationviaI2C)

Above1000Hz‐analog

(on‐interfaceanalogtodigitalconversion)

Measuringrange Differential‐12.5..+12.5mA

Resolution 14‐bit,±0.002mA

Accuracy Typical±0.5%andMaximal±1.0%atfullrange

Max.overcurrentprotection ±30mA

Max.voltageinputand

Max.overvoltageprotection

±0.5V(12.5mA)

±1.0V(25mA)

Resistancebetweeninputs 40.2Ω/0.1W

Maximalsamplingrate 100kHz

Zerooffset Zero‐voltageoffsetdrift:

typical±0.008mAat25°C

Sensordimensions Housing:42x18x16mm

Electriccords:length35cm;diameter3mm

Connection 5‐pinsminijackplug



Warranty:

The Current sensor ML23f is warranted to be free from defects in materials and

workmanshipfor aperiod of12monthsfrom the dateof purchaseprovided thatit

has been used under normal laboratory conditions. Thiswarrantydoesnotapplyif

thesensorhasbeendamagedbyaccidentormisuse.





Note: Thisproductistobeusedforeducationalpurposeso nly.Itisnotappropriate 

forindustrial,medical,research,orcommercialapplications.   

Rev. 15/05/2013

CMA Current Sensor User guide

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