India Broadband Forum

India Broadband Forum

A multimeter is a nifty little device to measure a lot of values related to current and electric circuits. It can be used to measure the potential difference (AC or DC), the amount of current in a circuit, the resistance of an electric component, the continuity of a circuit or even to test a transistor whether it is working correctly or not. It can be a handy little tool to have around the house for a variety of purposes like checking for blown fuses or even testing the integrity of the the earth connection in the electrical outlets. However it might be a little bit confusing for some to use which is normal. There are two types of multimeters available, namely the analog and the digital. The analog multimeter is useful in measuring varying currents and voltages while the digital provide more accuracy in general constant measurements. We are to discuss the digital multimeter below.

Two types of digital multimeters exist, a ‘switched range multimeter (which is more common) and the ‘autoranging multimeter’. The latter is more expensive compared to the former, but also easier to use. On a typical multimeter, a central knob or a rotating switch exists which is used to select the range (switched range) as well as the type of the value to be measured. There are two probes or leads which are connected to the multimeter on two of the three available sockets. One of the sockets is the COM (common) socket, which always has the black probe connected. The red probe is connected to the socket marked V mA. The third socket marked 10A, is used while measuring bigger currents but is generally hardly ever used.

All one has to do is identify the type of value that has to be measured, select the proper range according to an approximate value and read out the display. A person should keep in mind to start from the highest range available when measuring an unknown value to safeguard the multimeter from damage. Voltage and resistance are always measured in parallel to the circuit while the current is measured while keeping the multimeter in series with the circuit. Another feature of the multimeter is to test for continuity of a circuit, when it gives off a beep if a circuit is complete.