"Using the Voltmeter" A voltmeter is a device used to measure voltage. There are two main types of voltmeters, those with analog displays, which use magnetic dials, and those with digital displays, which use LED arrays or LCD screens. The ones with digital displays are typically more precise and, as a result, more costly. However, voltmeters with analog displays work fine for most everyday uses. Voltmeters are often combined with other meters in multimeters, allowing for different ranges of voltages to be shown with the mere turn of a knob. Most voltmeters or multimeters are quite inexpensive, with some being available for only a few US dollars.A voltmeter is used to measure voltage in circuits and from voltage sources. They are quite useful in diagnosing problems in circuits and determining the magnitude of the voltage from batteries and power supplies. For example, a power supply might say that it is outputting only 5 volts, but due to a malfunction it might actually be outputting 30 volts. Hooking this power supply up to a voltage-sensitive circuit may result in damage to the components. Therefore, it is useful to have a voltmeter to verify the voltage levels. Also, by placing the voltmeter probes across a component in a live circuit, one can determine the voltage drop of a component in a circuit. (voltage drops will be discussed in further detail later) A voltmeter has three necessary components, the first of which being a display to show the read voltage. There are also two leads, one meant for the positive polarity of the voltage and one meant for the negative polarity of the voltage. Mixing up the polarities on certain voltmeters with analog displays can prevent readings, but with most voltmeters using digital displays this crossing only results in a negative symbol being placed in front of the reading to indicate the reversed polarity. The range control knob is not present in all voltmeters, but is a very useful feature, allowing a person to select AC or DC as well as ranges of voltage.When a voltmeter has a range knob, it is a good practice to set the range at the highest setting for the proper voltage and work down from there. Although most voltmeters aren't damaged if there is a voltage overload, some are. Take special care with analog displays since hooking them up to alternating current without the AC setting can result in the meter switching back and forth rapidly, which can bend or break the meter pin. Most digital display voltmeters won't be affected by this issue, but will not display the voltage until set properly. 1. Find a DC battery of AAA, AA, C, or D size and grab a voltmeter
2. Turn the range knob (if present) to a DC setting as close as possible (but higher than) 2 volts
3. Hold the positive (usually red) probe tip on the positive (+) terminal of the battery
4. At the same time, hold the negative (usually black) probe tip on the negative (-) terminal
5. Watch the display, if the settings are right on the voltmeter, it should display a voltage, if not double-check that the voltmeter is set to a range of above 2 volts DC and the probes are contacting the terminals.1. Find an electrical outlet and grab an AC-capable voltmeter
2. Turn the range knob (if present) to an AC setting as close as possible (but higher than) 120 volts (240 volts for europeans)
3. Insert the positive probe into the larger rectangular opening of the outlet
4. Insert the negative probe into the smaller rectangular opening of the outlet
5. Watch the display, if the settings are right on the voltmeter, it should display a voltage, if not double-check that the voltmeter is set to a range of above 120 volts AC and the probes are contacting the terminals inside of the outlet.Caution!
The voltage of household
electrical outlets is sufficient
to severely harm or kill a human!
Therefore, take care to hold onto
the insulated leads and not touch
the metal tip! For added safety, you
may wear rubber gloves.Congratulations! Now that you have learned the basis of the voltmeter and how to use it, you have gained important knowledge and experience with electricity and electronic measurement tools. If you choose to pursue electronics as a hobby or career, usage of the voltmeter will soon become secondhand. Try measuring the voltage of different batteries that you have never seen before, like the battery in your automobile or watch as practice! Just remember, safety first. It is reccommended to wear leather or rubber gloves if you are uncomfortable with measuring unknown voltages.