Conclusion DC Multimeter

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DISCUSSION:

IN THE EXPERIMENT WE ARE ABLE TO DETERMINE

THE CHARACTERISTIC OF OUR METER MOVEMENT AS A

MULTIMETER. THE MOST IMPORTANT THING WE LEARNED

IN THE EXPERIMENT IS THAT WE ARE ABLE TO KNOW

HOW TO USE OUR PANEL METER NOT ONLY AS A NEITHER

SIMPLE AMMETER NOR VOLTMETER BUT AS A

MULTIMETER WHERE WE CAN MEASURE THE VOLTAGE,

CURRENT, AND RESISTANCE IN ONE CIRCUIT.

IN THE EXPERIMENT, FIRST WE DETERMINE OUR

PANEL METER LIMITS ON HOW MUCH VOLTAGE AND

CURRENT IT CAN HANDLE. IN THIS WE FOUND OUT THAT

APPLYING TOO MUCH CURRENT TO THE METER

MOVEMENT, AS MOVEMENTS ARE VERY SENSITIVE

DEVICES AND EASILY DAMAGED BY OVER CURRENT. OURMETER MOVEMENTS HAVE FULL-SCALE DEFLECTION

CURRENT RATINGS OF 100 uA SO WE CHOOSE A

POTENTIOMETER THAT HAS A VALUE HIGH ENOUGH TO

LIMIT CURRENT APPROPRIATELY, AND BEGIN TESTING

WITH THE POTENTIOMETER TURNED TO MAXIMUM

RESISTANCE. THE LOWER THE FULL-SCALE CURRENT

RATING OF A MOVEMENT, THE MORE SENSITIVE IT IS.

AFTER DETERMINING THE FULL-SCALE CURRENT

RATING OF OUR METER MOVEMENT, WE ACCURATELY


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MEASURE ITS INTERNAL RESISTANCE. TO DO THIS, WE

DISCONNECT ALL COMPONENTS FROM THE PREVIOUS

TESTING ON THE CIRCUIT AND CONNECT OUR DIGITAL

OHMMETER ACROSS THE METER MOVEMENT TERMINALS.

RECORD THIS RESISTANCE FIGURE ALONG WITH THE

FULL-SCALE CURRENT.

IN ADDITION TO THAT WE MADE THE OHM METER IN

THE EXPERIMENT. AND FOUND OUT THAT WHEN THERE IS

INFINITE RESISTANCE, THERE IS MINIMUM CURRENT

THROUGH THE METER MOVEMENT, AND THE NEEDLE

POINTS TOWARD THE FAR LEFT OF THE SCALE. IN THIS

REGARD, THE OHMMETER INDICATION IS BACKWARDS

BECAUSE MAXIMUM INDICATION IS ON THE LEFT OF THE

SCALE, WHILE VOLTAGE AND CURRENT METERS HAVE

ZERO AT THE LEFT OF THEIR SCALES.

ALSO IN THE EXPERIMENT WE FOUND OUT THAT

OHMMETERS CONTAIN INTERNAL SOURCES OF VOLTAGE

TO SUPPLY POWER IN TAKING RESISTANCE

MEASUREMENTS.

ANALOG OHMMETERS ALSO HAVE NONLINEAR

SCALES, "EXPANDED" AT THE LOW END OF THE SCALE

AND "COMPRESSED" AT THE HIGH END TO BE ABLE TO

SPAN FROM ZERO TO INFINITE RESISTANCE.


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AND LASTLY WE ARE ABLE TO KNOW THAT

OHMMETERS SHOULDNEVERBE CONNECTED TO AN

ENERGIZED CIRCUIT. ANY VOLTAGE APPLIED TO THE

TEST LEADS OF AN OHMMETER WILL INVALIDATE ITSREADING.

CONCLUSION:

BASED ON THE RESULT OF THE EXPERIMENT,

THE FOLLOWING CONCLUSIONS WERE INFERRED:

1. THE MULTIMETER GIVES US ONEPIECE OF

EUIPMENT THAT CAN BEUSED TO MEASURE

RESISTANCE, CURRENT, AND VOLTAGE.


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!. VERIFYING THEORETICALLY CALCULATED

RESULTS USING BASIC NETWORK LAWS IS

NEEDED TO COME UP WITH VALUES THAT

WILL BE STIPULATED IN CREATING A DC

MULTIMETER.

". PROFICIENCY CREATING ELECTRICAL

CIRCUITS USING RESISTORS, WIRES AND

POWER SUPPLIES IS IMPORTANT TO MEET THE

DESIRED SPECIFICATIONS IN CREATING THE

DC MULTIMETER

COMPUTATION:

VOLTMETER MULTIPLIER RESISTOR


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CALCULATED (SCALE 2 V

RIN ! .#2$ K OHMS

(FV%FA & RIN

(2 V % ''UA .#2$ K OHMS

RS ! #.$ K OHMS

CALCULATED (SCALE 2' V

RIN ! .#2$ K OHMS

(FV%FA & RIN

(2' V % '')A .#2$ K OHMS

RS ! *#.$ K OHMS

CALCULATED (SCALE $' V

RIN ! .#2$ K OHMS

(FV%FA & RIN

($' V % '')A

.#2$ K OHMS

RS ! +*#.$ K OHMS



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MEASURED (SCALE 2 V

RIN ! .*$ K OHMS

(FV%FA & RIN

(2 V % '')A .*$ K OHMS

RS ! #.'$ K OHMS

MEASURED (SCALE 2' V

RIN ! .*$ K OHMS

(FV%FA & RIN

(2' V % '')A .*$ K OHMS

RS ! *.+'$ K OHMS

MEASURED (SCALE $' V

RIN ! .*$ K OHMS

(FV%FA & RIN

($' V % '')A

.*$ K OHMS

RS ! $'2.2'$ K OHMS


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MILLIAMETER SHUNT RESISTOR

CALCULATED (SCALE '' A

- ! (I % IM

RSH! ( RM% (- ///

- ! ( '' A % '')A

- ! '''

RSH ! ( .#2$ K OHMS % ('''

RSH ! .#$ OHMS

CALCULATED (SCALE ' A

- ! (I % IM

RSH! ( RM% (-

///

- ! ( ' A % '')A

- ! ''

RSH ! ( .#2$ K OHMS % (''

RSH ! #.+0 OHMS


8/15

MEASURED (SCALE '' A

- ! (I % IM

RSH! ( RM% (- ///

- ! ( '' A % '')A

- ! '''

RSH ! ( .*$ K OHMS % ('''

RSH ! .* OHMS

MEASURED (SCALE ' A

- ! (I % IM

RSH! ( RM% (-

///

- ! ( ' A % '')A

- ! ''

RSH ! ( .*$ K OHMS % (''

RSH ! #.0 OHMS


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RANGE

FOR RANGE ! 2 V

RSH! S X RANGE & RM

RSH! ( % '' )A 1 2 V .*$ K OHMS

RSH! #.2'$ K OHMS

FOR RANGE ! 2' V

RSH! S X RANGE & RM

RSH! ( % '' )A 1 2' V .*$ K OHMS

RSH! *#.2'$ K OHMS

FOR RANGE ! $' V

RSH! S X RANGE & RM

RSH! ( % '' )A 1 $'V

.*$ K OHMS

RSH! +*#.2'$ K OHMS


10/15

PERCENTAGE ERROR


COMPU

TED

MEASUR

ED

P34-567

E3383

9

2 V

#.$

K OHMS

#.'$

K OHMS

9 E ! ( (#.$

#.'$ % #.$

1 ''

'.0#

$9

2' V

*#.

$ K

OHMS

*.+'$

K OHMS

9 E ! ( (*#.$

*.+'$ % *#.$

1 ''

'.0#

*9

$' V

+*#.

$ K

$'2.2'$

K OHMS

9 E ! ( (+*#.$

$'2.2'$ % +*#.$ '.#


11/15

OHMS1 ''

#9

MILLIAMMETER SHUNT RESISTOR

COMPU

TED

MEASUR

ED

P34-567

E3383

9

'

A

#.+0

OHMS

#.0

OHMS

9 E ! ( (#.+0

#.0 % #.+02

1 ''

.;229

''

A

.#2OHMS

.*OHMS

9 E ! ( (.#2 .* %

.#2

1 ''

.;+

29


12/15

TROUBLESHOOTING

MEASU

RED

COMPUT

ED

P34-567

E3383

9

#.+

KOHMS

#.2'

KOHMS

9 E ! ( (#.2' #.+ %

#.2'

1 ''

'.00

9

*.2'

$ KOHMS

*#.2'

' KOHMS

9 E ! ( (*#.2''

*.2'$ % *#.2

1 ''

'.$'

29


13/15

+**

K

OHMS

+*#.2

K

OHMS

9 E ! ( (+*#.2 +** %

+*#.2

1 ''

'.;

9

2$

K

OHMS

2;.+

K

OHMS

9 E ! ( (2;.+ 2$ %

2;.+

1 ''

'.;+

9

$;

K

OHMS

$;.+

K

OHMS

9 E ! ( ($;.+ $; %

$;.+

1 ''

'.'

9

;*;

K

OHMS

;*;.+

K

OHMS

9 E ! ( (.#2 .* %

.#2

1 ''

'.'$

9

STEP +

MEASU COMPUT P34-567 9


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RED ED E3383

#.$K

OHMS

#.2'KOHMS

9 E ! ( (#.2'

#.$ %#.2'

1 ''

.;+

#9

STEP $

MEASU

RED

COMPUT

ED

P34-567

E3383

9

.*

KOHMS

.#2

KOHMS

9 E ! ( (.#2 .* %

#.2'

1 ''

+.+'

9

REFERENCE:

HTTP:%%WWW.ALLABOUTCIRCUITS.COM%VOL


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HTTP:%%WWW.ALLABOUTCIRCUITS.COM%WORKSH

EETS%METERS2.HTML

HTTP:%%WWW.ALLABOUTCIRCUITS.COM%VOL

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Conclusion DC Multimeter