EXPERIMENT - 6 :- IDENTIFICATION OF METER TYPES AND MEASURING RANGE

1. Aim of the Experiment

To identify various electrical and electronic measuring meters, understand their selector switch positions, select proper measuring ranges, and master step-by-step procedure for measuring AC and DC voltages safely and accurately using a Multimeter[cite: 2].

2. Required Tools, Instruments & Components

S.N.	Equipment / Tool Description	Specification / Range	Quantity
1	Digital Multimeter (DMM)	3½ Digit, Auto/Manual Ranging, CAT III 600V[cite: 2]	1 No.[cite: 2]
2	Analog Multimeter	20kΩ/V DC, Moving Coil Type[cite: 2]	1 No.[cite: 2]
3	Variable DC Power Supply & Batteries	0–30V DC, 1.5V AA Battery, 9V Battery	1 Set
4	Test Probes / Leads	Red (Positive) & Black (COM) Leads[cite: 2]	1 Pair[cite: 2]

Digital Multimeter Guide

How to Read, Select Ranges & Measure Electrical Values

Multimeter Interface & Ports

How to Measure Step-by-Step

• 1. Connect Probes:
  • Black Lead $\rightarrow$ Always into COM Port.
  • Red Lead $\rightarrow$ Into V Ω mA Port (for Volts, Ohms, Low Current).
• 2. Select Function Mode:
  • V~ for AC Voltage (Wall outlets).
  • V= for DC Voltage (Batteries, DC Circuits).
  • Ω for Resistance / Continuity check.
• 3. Select Range:
  • If range is unknown, set to Highest Value first, then decrease for accuracy.
• 4. Connect to Circuit:
  • Voltage: Measure in PARALLEL across component.
  • Current: Measure in SERIES (break circuit).

Range Selection & Settings Reference

Measurement	Dial Setting	Typical Range	Connection Method
DC Voltage (Batteries, Adapters)	V= / VDC	200mV, 2V, 20V, 200V, 600V	Parallel (Red to +, Black to -)
AC Voltage (Wall Socket, Mains)	V~ / VAC	200V, 600V / 750V	Parallel (Polarity doesn't matter)
Resistance (Resistors, Coils)	Ω (Ohm)	200Ω, 2kΩ, 20kΩ, 2MΩ	Parallel (Circuit must be POWER OFF)
DC Current (Small Circuits)	mA / A	2mA, 20mA, 200mA, 10A	Series (Break the path to place meter)
Continuity (Wire test, Fuses)	Beep Symbol / Diode	Single Setting	Parallel (Beeps if circuit is complete)

Important Safety Rules

• Never measure Resistance or Continuity on an energized (live) circuit.
• Never connect leads in 10A port to measure Voltage—this creates a dangerous short circuit!
• If display shows "OL" or "1 .", the value exceeds chosen range. Dial to a higher range.

Educational Blueprint Series • Easy Visual Guide for Electronics & Electrical Measurement

Figure 2: Correct Parallel Connection for Voltage Measurement[cite: 2]

5. How to Measure & Read Volts (Step-by-Step)

Step 1: Insert Test Leads into Correct Ports

• Plug the Black probe into the COM (Common) jack[cite: 2].
• Plug the Red probe into the V Ω mA jack[cite: 2].

Step 2: Select Voltage Mode & Range

• For DC Voltage (Batteries, Adapters), set switch to V=[cite: 2].
• For AC Voltage (Wall Outlets), set switch to V~[cite: 2].
• Manual Ranging Rule: If estimated voltage is unknown, set the dial to the highest available range (e.g., 600V or 1000V)[cite: 2]. Then dial down to a lower range for better precision[cite: 2].

Step 3: Connect Probes to Circuit

• Touch probe tips across the two points you want to measure (in parallel)[cite: 2].
• Hold probes by insulated handles; do not touch metal tips.

Step 4: Reading the Display

• Digital Multimeter: Read numerical value on screen directly (e.g., 12.05 V)[cite: 2].
• Negative Sign (-) on DC: Means red and black leads are reversed. Value remains correct.
• Overload Symbol (1 . or OL): Means selected range is too low[cite: 2]. Immediately switch dial to a higher range[cite: 2].

6. Voltage Range Selection Guide

Target Signal	Mode Symbol	Recommended Range Setting	Expected Reading
1.5V AA / AAA Battery	DC Voltage (V=)[cite: 2]	2V or 20V DC[cite: 2]	1.5V – 1.6V
12V Car Battery / Power Supply	DC Voltage (V=)[cite: 2]	20V or 200V DC[cite: 2]	12.0V – 12.8V[cite: 2]
230V AC Domestic Mains Supply	AC Voltage (V~)[cite: 2]	600V or 750V AC[cite: 2]	220V – 240V AC[cite: 2]

7. Practical Observation Table

S.N.	Voltage Source Tested	Selected Dial Range	Observed Reading	Status / Remarks
1	Variable DC Power Supply[cite: 2]	DC 20V[cite: 2]	12.05 V[cite: 2]	Normal Operating Voltage[cite: 2]
2	AC Mains Outlet (Single Phase)[cite: 2]	AC 750V[cite: 2]	232.0 V[cite: 2]	50Hz Standard Mains Voltage[cite: 2]
3	1.5V Cell Battery	DC 2V	1.54 V	Fully Charged Cell

Safety Warnings for Voltage Measurements

• Check Probe Position: Ensure Red lead is NOT in the 10A terminal[cite: 2]. Measuring voltage with probe in 10A port causes a massive short-circuit!
• Select Correct Function: Never measure AC voltage while multimeter dial is set to Current (A) or Resistance (Ω)[cite: 2].
• High Voltage Safety: Keep fingers behind probe hand-guards while testing AC mains voltage[cite: 2].

8. Conclusion

The practical understanding of meter types, selector switch ranges, and step-by-step voltage measurement was successfully demonstrated. AC and DC voltage values were accurately measured and recorded under safe practical conditions[cite: 2].