Analog Multimeters
Analog multimeters are electrical test instruments which are used to measure voltage, current, resistance, frequency and signal power.
Analog multimeters use a needle along a scale. Switched range analog multimeters are very cheap but are difficult for beginners to read accurately, especially on resistance scales. Each type of meter has its advantages. Used as a voltmeter, a digital meter is usually better because its resistance is much higher, 1 M or 10 M, compared to 200 for a analog multimeter on a similar range. On the other hand, it is easier to follow a slowly changing voltage by watching the needle on an anlaogue display. Used as an ammeter, nalog multimeters have a very low resistance and is very sensitive. More expensive digital multimeters can equal or better this performance. Most modern multimeters are digital and traditional analog multimters are becoming obsolete.
The basic functionality of an analog multimeter will include measurement of electrical potential in volts, resistance in ohms, and current in amps. Analog multimeters can be used to find electronic and electrical short circuit problems. Advanced analog multimeters come with more features such as capacitor, diode and IC testing modes. Specific measurements made by analog multimeters include DC voltage, AC voltage, DC current, AC current, frequency range for AC currents, and decibel measurement. Analog multimeters that measure current may have a current clamp built-in or configured as a probe. A current clamp is a sensor that clamps around the wire. When searching for analog multimeters it is important to consider the measurement range for whichever value is being measured. An analog multimeter displays these values via a dial, typically a moving pointer or needle. Analog multimeters are generally bench top or hand held. Bench top models can also be portable by use of handles and wheels. Hand held multimeters are specifically designed to be used while holding, i.e, can be operated with one hand.
Analog multimeters have multiple scales on the dial, a moving needle and many manual settings on the function switch. It’s tricky spotting the correct scale to read on the dial, plus you sometimes have to multiply the reading by 10 or 100 to get your final value. Depending on features (make sure it can do continuity testing), prices start at about $15.
For appliance and electronic repairs, it may be better to purchase a digital, not analog, multimeter. This type is much simpler to read and you can change the functions on it more easily. Digital multimeters (Photo 2) have LCD readouts, do continuity testing, and cost from $35 on up. Some digital multimeters also feature auto-ranging and overload protection and other advantages analog multimeters lack.
For easier, hands-free viewing, choose an analog multimeter with a stand that will prop it up or hang it on a wall. If an analog multimeter doesn’t come equipped with either jumper wires or alligator clips (both about $4 each), buy them. Alligator clips are often used to firmly grip wiring or contacts for hands-free safe and accurate readings. Both types of multimeters and these accessories can be purchased at electronics stores, home centers and hardware stores.
Common features for analog multimeters include battery power, overload protection, temperature compensated, mirrored scale, range switch, diode test, and battery test. Devices with battery power can be operated without plug in power. Multimeters with overload protection have a fuse or other method to protect meter. Temperature compensated devices have programming or electrical devices designed to counteract known errors caused by temperature changes. A mirrored scale makes it easier to read the instrument to a given accuracy by enabling the operator to avoid parallax errors. A range switch is used to select appropriate range of units to be measured. A device with a diode test has methods for testing diode operation. A device with a battery test has methods for testing battery operation. An important environmental parameter to consider when searching for analog multimeters is the operating temperature.
|  |
