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Once reserved for railroad engineer and electronic technicians , multimeters — sometimes call “ multitesters”—have come down in price and sizing , making them essential for homeowners who have canonic noesis of circuitry . Whentroubleshooting problemswith small appliances , fresh - home modules , utterer systems , or just about any other electronic item , a multimeter will be among the most assess tools in your arsenal .
If you ’re young to multimeters , these convenience may seem daunting at first . Learn the bedrock , however , and you ’ll soon be able to perform a number of symptomatic tests on your own . Because multimeters vary from mannequin to poser , be sure to canvass your specific unit ’s operating manual of arms before you get started .
How to Use a Multimeter
Types of Multimeters
Analog multimeters , or V - Georg Simon Ohm - milliammeters ( VOM ) , have been around for decades and can still be found , affordably , at any do - it - yourself - character store . The new kids on the closure — digital multimeters ( DMM)—offer greater precision with decimal spot read-out , even enhance use , such as the ability to auto - detect alternate current ( AC ) or direct current ( DC ) .
Applications and Limitations
Both VOM and DMM example measure electric potential , immunity , and current , replace the need for single voltmeters , ohmmeter , and ammeters . While you may try out household voltage with a multimeter , electrical - current - testing is limited to low - voltage circuits , such as small direct current ( DC ) motors or miserable - voltage alternating current ( AC ) appliances — your thermostat anddoorbells , for illustration . To ward off blowing a primer , destroying the multimeter , or risking harm , do not attempt to test current higher than the upper limit allow for for your unit .
Among other things , multimeters can shape :
Tried-and-True Advice
“ The first time I used a multimeter , I found the most thought-provoking part was deciphering the hieroglyphical - like options on the front of the social unit , and decoding strange readings that would sometimes look on the display . While there are certainly common attribute from multimeter to multimeter , not all convey with you in the same way . For example , a multimeter may expose either OL , 99999 , or 1 if it ’s overloaded , calculate on the brand and model . Take the metre to say through your multimeter ’s education manual to get introduce with its control and display readings before you dive in and start using it . ”
— Tony Carrick , Contributing author
Measuring Voltage
With a multimeter , you’re able to evaluate both AC and DC potential difference — particularly useful for locating brusk circuit or limit if a rechargeable stamp battery is holding a accusation . Start by selecting the corresponding current on the multimeter and a voltage range high than the flow you ’re test . For example , if you ’re measuring the emf in a 120 - V wall outlet , grow the multimeter knob to the next highest pick , 200 ACV . If you ’re prove a 12 - V auto battery , pick out the next highest choice , 20 DCV .
Then make certain to join your psychometric test leads to the proper jacks before prove : For voltage testing , plug away the cherry lead in to the port label “ V. ” For this andallmultimeter tests , the black lead plug into the common ( COM ) port .
To test a barrage fire ’s DC charge , touch the red probe to its positive terminal and the black investigation to its negative terminal ; the multimeter will exhibit the exist charge in the bombardment . Since polarity is n’t an issue in AC potential , it does n’t weigh which poke into you insert in either trap of a wall exit ; insert both probes , and the multimeter will display the electromotive force at the outlet .
Safety Tip : Hold probe by their insulated hold . Donottouch the metallic element part of the probes to invalidate electric shock absorber .
Testing Resistance and Continuity
In electronics , “ resistance , ” is the amount of balk to the flow of electricity , and less is more — or , rather , good for the mathematical process of your appliances . Multimeter in hand , you’re able to test resistance in circuit control panel ingredient and appliance constituent throughout the house . If , for example , amicrowaveisn’t operating as it should , this medical exam could aid you you see if you should replace a exclusive non - functioning component on the circle circuit card or purchase a raw microwave in a flash .
First , make certain the appliance is unplugged before testing . Plug the red lede into the port with the ohm ’s symbol , “ Ω , ” and select the lowest ohms ’ occasion on the dial . While you may screen single capacitors and component directly on a circuit panel , you ’ll get a more precise meter reading if you dispatch a component and then test it . When you touch the black and red probes to both ends of a component , simultaneously , you ’ll get a reading . The dispirited the reading , the less the impedance to electric flow . By comparing the readings from other components on the circuit control panel , you may determine whether or not to supervene upon a component with an remarkably high reading .
To prove the continuity , or uninterrupted flow , of an electrical track between two points , plug the red lead into the “ Ω ” Jack-tar and turn the dial to the persistence symbol . A pocket-size recitation — or a beep — indicates there is a uninterrupted path between the two points . No reading or bleep , however , indicates a job . For example , if you ’ve just put a newfangled bulb in your lamp but itstilldoesn’t turn on , running this test at both end of its power cord can confirm that an internally break cord is to pick for your dim way .
Testing Low-Voltage Current
so as to quantify scummy - electric potential stream , the multimeter must become part of the circuit , allowing the current to in reality run through the multimeter . This is handy for determining whether a broken - voltage electrical circuit , such as a looped set of solar - poweredlandscape lights , is beget big businessman to all the light . For this test , plug the violent steer into the port mark , “ A , ” for Amps , and select the next - high Amps role on the dial .
Your operating manual of arms may furnish a chart , but if not , you may test a childlike circuit by link the live provender from the power - supply ( usually black ) to the multimeter ’s blood-red investigation . The multimeter ’s black probe then get in touch to the positive wire ( normally sinister ) on the appliance you ’re testing . lastly , the impersonal power - supply lead ( usually whitened ) link up to negatively charged gismo conducting wire ( also whitened ) . When you ’ve hooked up the circuit aright , turn on the index source to measure the electric menstruum charge per unit , or adenosine monophosphate , through the electrical circuit .
Safety Tip : As antecedently mention , donottest a circuit that outstrip your multimeter ’s capability . Multimeters are “ combine ” at a maximum amount of potential , which is typically low-down than menage current . If a multimeter contain the quarrel , “ 10A MAX FUSED , ” do not examine any current you suspect might be higher than 10 Amps .
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