A typical diagnostic tool for technicians in the electrical or electronic industry, multimeters, as the name suggests, can measure current, voltage, resistance, and continuity. These are the basic measurements that a simple multimeter can provide. As a technician becomes more experienced, complex multimeters that give more measurements are required. There are analog multimeters that have a moving pointer to indicate values and a digital one with digital readings. Today digital multimeters or DMMs are used more than analog ones.
Use of multimeters:
Multimeters are used to test circuits during debugging and batteries. Usually, the range must be established before obtaining the actual measurements. Depending on the expected value, this range can be set manually or has autoranging capabilities. A range of twenty microamps to milliamps to 10 amps max, 200 microvolts to 600 volts, and 200 ohms to kilo ohms to 20 mega ohms… these are the ranges normally. It can be used for alternating and direct current by turning the knob appropriately. Autoranging multimeters display the unit for the reading.
A multimeter shows the average current. Capacitors and inductors have an initial rise in current that cannot be detected by a multimeter and would require an oscilloscope to detect and measure.
Diode continuity tests are to detect its polarity. Diodes (and resistors) must be separated from any power source before making measurements on them. In a circuit, the continuity of the diodes is indicated by a beep.
multimeter applications
HVAC systems
amateur radio applications
mobile repair
Multimeter Categories
There are four categories based on their applications ranging from low risk CAT I to high risk CAT IV.
Each category rating specifies the safe step voltages for the measurement ranges on the multimeter. Meters rated by category have built-in protection against current overloads.
Some advanced features of multimeters:
Capacitance reading
frequency reading
With a thermocouple probe, temperature readings are possible
Reading storage and transfer capabilities via USB
· All technicians have a multimeter handy as it is the first diagnostic tool available for debugging circuit designs in electronics.
Ability to interact with computers.
What to look for when buying a multimeter:
These are the conditions that must be met when choosing a multimeter:
· Safety features: must be CAT rated and have a built-in fuse for high currents.
· Voltage range and accuracy of readings: depends on what you buy it for. If it’s for household circuits, the measurements don’t need to be as precise as you’d need for electronic circuits. You would need AC and DC metering capabilities in most cases.
· Durability and size: it must be of good quality to withstand a few drops from time to time. Many technicians prefer a convenient size that fits in their pocket, but for an irregular user, a large size might be more useful, with easy-to-read values.
· Accessories: probes with banana plugs, needle-nose probes, alligator clips, probes with clips, and a temperature probe that is useful in HVAC applications.
· Warranty: Some manufacturers offer a lifetime warranty, the term lifetime is defined differently for each one! Others give a one year warranty. A lifetime warranty is always better, whatever term you list would be better than a one year warranty.
Price: Don’t compromise on price if that’s a complicating factor, as all other features between models are the same. This is a security issue, so if all the security features are in place, feel free to spend a little more.
