EVERYONE Needs a Multi-Meter

A multi-meter can save the average person a lot of money over a few years, even though ladies who choose to buy one may not carry it in their purse when going out for the evening. You will often be able to solve many problems yourself in less time than it would take to get a technician to come to your home. This Instructable will show how to do that simply and easily.

I often meet handy people, both men and women, who do not go near to anything electrical because they are frightened of electricity. It is good to have a strong respect for electricity. It is also good to know how to make basic electrical measurements around the home. A multi-meter is the tool every home ought have. They eliminate the guess work from so many things and can save a lot of money. 

A suitable multi-meter for occasional use around the home and automobile can be had for less than $ 5. This link is to a very inexpensive meter that includes some functions found only on meters costing twenty times more just a few years ago. More expensive meters do not necessarily have more features. They give greater accuracy for professional work, and they are more rugged in their construction and durability.

Step 1: Will I electrocute myself?

No, that will not happen if you follow a few simple precautions. Most home uses of a multi-meter will be done with the power disconnected, or with very harmless low voltages. Regardless, you will always handle the probes by their well-insulated, completely safe plastic "handles." Usually, you will hold one in each hand.  

The black probe is normally associated with the ground or negative terminal. The red probe is normally associated with the "hot" or positive terminal. For household uses illustrated in this Instructable you can ignore all of that and use either probe on any terminal. 

Comments

[J,R,D, Ltd]

Well, it did save you money in a way because you didn't have to pay a mechanic $60-$100+ an hour to find that problem.

[Phil B]

You are quite correct. I am so accustomed to doing whatever work I can on my car that I do not even think about what I would have paid at a garage, not to mention towing the car to the garage. Thank you for looking and for your comment.

[The nerdling]

i brough a multimeter to school, because you never know ehn you might need it and people kept asking waht it was, i was famouse for a little bit

[Phil B]

One day they will wish they had been more like you and learned to use a meter. Thank you for looking.

[jchamberlain]

I can't tell you how many times I have pulled my meter out only to have someone ask "what's that?". I have saved time and money for sure. Awesome and informative instructable sir.

[Phil B]

Thank you for looking and for commenting. This Instructable attempts to explain uses for a meter I have found in everyday needs. I expect my experiences are close to those of others. Have you used your meter for some common needs I missed? Thank you again.

[jchamberlain]

I have several TV monitors around the house linked with coax cable. Sometimes in order to troubleshoot them I use the continuity setting, I have someone short out one side using metal to touch the center pin to the outer connector. I then use the two probes to check my various cables to identify them.

This also allows me to identify which cable connects to which device at friends homes when helping them connect TV, satellite or other antenna.

Jeff

[Phil B]

I have a spool of bell wire I use to connect to a wire at a wall box a couple of rooms away. The continuity tester or the Ohms scale lets me check for a break in the wire inside the wall. I once found a broken wire inside a ceiling box this way, even though there was no visual hint of the break. Thank you for the information on how you use your meter.

[darman12]

Just the title made me proud to own one :)

[Phil B]

I am glad you already have a multi-meter. You will find a lot of uses for it throughout your life.

[fretted]

I've got one of these meters from harbor freight i'm glad you wrote this Ible now i can use it where i didn't have a clue before how to start now i know

Thanks for a great Ible

[vanwazltoff]

i was subscribed to a magazine that had free DMM coupons for harbor freight, i think i have 3 freebies now, one for my tool box, one for my car, one i gave to my dad. i have a more expensive DMM for my electronics tool box. i find a reason to use one all the time

[vanwazltoff]

i was subscribed to a magazine that had free DMM coupons for harbor freight, i think i have 3 freebies now, one for my tool box, one for my car, one i gave to my dad. i have a more expensive DMM for my electronics tool box. i find a reason to use one all the time

[Phil B]

Those are not bad little meters for home use. I think I have one,too; but, I got mine at Home Depot and paid a lot more for it. I did this Instructable for people in your situation.

[fretted]

Before i read this i really didn't have much of a clue how to use it on much thanks for this ible now i understand a-lot more about it and how to use it now if i could just get a handle on basic electronics i''ve got a-lot of ideas for LED's and and some cool steam-punk stuff I've fallen into this steam Victorian era kick and can't seem to throw it off i find some of these things very fascinating to build and goof around with and of course my nieces love the stuff ...

[Phil B]

There are some good basic books on electronics for the person who wants to learn on his own. There are also some good tutorial sites on-line. Here is a link to a pretty good circuit simulator that allows you to test circuits without the expense of buying real parts. If you go to this link, you can download an older version of the US Navy Electronics Course for free. I apologize for taking so long to respond to your comment. I wish you well.

[fretted]

Hey np problem and thanks for the links i'll be checking them out !

[Phil B]

When I was much younger I was very interested in radio circuits and wanted to learn all about them. Years later I met someone who had studied electronics by means of a famous (at the time) mail correspondence course. He said he did not use most of what he learned, but found what he had learned about power supplies gave him all he used and needed. Many things these days run on 5 volts, which is the exact output of a USB port and also an old phone charger. Once plug-in power supplies contained transformers with real copper wire. Now most are switched mode power supplies. The older style allowed adding a variable voltage regulator chip configured to the exact voltage you needed. The new style does not work with the regulator chips (as best I can determine). I wish you well. You will have fun with your electronics learning. Be aware some published circuits have bugs in them and when they do not work, it is not your fault.

[fretted]

lol np = no

[tim_n]

thanks for the overview. I've read this and the sparktronics tutorial and it all makes a lot of sense - though I didn't read anything about the different sockets in yours (10A?) for mains voltages?

Either which way, I'm off to do some soldering today and play with the multimeter to make an RFID arduino door lock!

[Phil B]

Generally, you can do most of your work with the COM and + sockets. But, when measuring the current flow in a circuit you need to match the current type, AC or DC, on the dial with the current type in your circuit. You also need to use the socket appropriate to the current level expected. Recently, I wanted to check the parasitic current draw my automobile makes from its battery when everything is supposed to be "off." If the door has been opened recently and the interior dome light is "on," the current draw rose to 2.99 amperes. That meant I needed the dial set to the 10 A DC range. It also meant I needed to use the 10 A socket and the COM socket. If I had been measuring current in an AC circuit and it was expected to be more than milliamperes, I would have needed to use the same sockets, but change the dial to the 10 A AC setting. Which socket to use more concerns the type and level of current expected than the voltage.

[Nano_Burger]

You can add this use to your list of common uses for a VOM (common for me anyway).

http://www.instructables.com/id/Attack-of-the-Killer-Strobes/

I use my VOM to repair cameras all the time. Luckily, I'm dealing with pretty low voltages and amperages to make it absolutly safe. The only risks are when dealing with photo flash capacitors.

[tim_n]

I have a vague memory when on holiday with friends of breaking open a disposable camera and taking the AA battery out for my walkman. Saw what I thought was a 2nd AA battery and broke the camera open further to get it out.

Que burst of light from flash and large electric shock. It was the biggest capacitor I'd seen at 11 years old, same size as an AA battery.

Most people might have stopped playing with it at this point, but I recharged it and said to my mate 'go-on, touch those two wires'

He didn't die and he learnt a life long lesson on what not to touch in electronics.

[Phil B]

Thank you for your comment. I read your Instructable on checking trigger voltages of electronic flash units. I have two digital cameras, neither of which has a hot shoe. In the days of film cameras I did have a couple of Vivitar 283 units and used them with slave triggers for multiple flash. What I had really been looking to find was a way to use my 283s with a slave trigger that would get around the pre-flashes on most built-in flash units used on cameras like mine. I once found a schematic for a home built delaying trigger and built it, but it did not work.

When I did this Instructable on using an electrical meter, I hoped people would take the basic things I showed and expand their usage to special purposes like yours.

[raziz]

i've seen a few old-timer mechanics turning on the wiper to check the battery strength when a car is having trouble starting.. i guess the wiper cranks more amps then the headlights.. once a car gone dead on me, even the instrument panel was blacked-out, it turned out the alternator had failed completely..

[Phil B]

I am sure that would work. I used to buy repair manuals by Motor's. They always had excellent general diagnostic and repair material in the front section of the volume. Another technique was to turn on the headlights and have someone attempt to crank the engine. The engine should turn over with the lights dimming only slightly.

[qazxsw21000]

Another example of how a multimeter (and troubleshooting skills) can save a few hundred bucks.

[Taerzik]

Thank-you for putting this together. I agree, everyone needs a multimeter (and the knowledge to use it of course.) I only got one a couple years ago and I'm still not fully proficient with it but it's been a really handy tool. I'd say most folks should know how to do basic soldering as well - it's pretty common to hear about common electronics that fail due to a faulty component, often a capacitor and how DIY'ers figured out how to fix it. Just the other day I re-soldered a loose capacitor in a faulty power supply - saved myself somewhere between $10 -30.

[Phil B]

Thank you for looking at this. Soldering is a very useful skill. One of the most helpful things I learned about soldering was to heat the parts of the joint so that they, rather than the soldering iron, make the solder flow. That is still a good principle, but now many of the semi-conductor parts are very heat sensitive and care is needed to avoid ruining a component. I yielded and added a low-wattage soldering iron to my old soldering gun. Congratulations on saving your piece of equipment and saving some money.

[nowuknowjack]

A couple of safety tips.
If you have to open a breaker panel/bus box, BEFORE you open it, touch the door with the back of your hand. An electric shock will cause you muscles to contract so if, by chance there is a problem and the panel is HOT, the electric current will force your muscles to draw your hand AWAY from the hot panel. You will get a shock, but will live to tell about it.
Next, in choosing a multi-meter, get the highest category you can afford. The higher CAT rating the better protection if something goes wrong. The higher protection will help keep the multi-meter from exploding due to a power surge. CAT IV is the best option if you can afford it.
Finally try to hold the leads in ONE HAND when testing higher voltage circuits such as 110 AC. If something goes wrong only your hand will be affected. If you happen to be holding the leads one in each hand and there is a short, the path of least resistance is from one hand to the other and your heart just happens to be in that path.

[nowuknowjack]

I see the one hand rule and CAT ratings were covered in earlier comments, sorry for the repetition. One other suggestion if opening a panel is to wear safety glasses or a face mask and cotton...NOT POLYESTER...long sleeve shirt. YES I am a safety freak, but my college instructor could not emphasize safety enough... "Gentlemen, when I was growing up in Argentina, they gave me a light bulb and two wires to test circuits. You must know how to do this safely and memorize this information so you do not get electrocuted!"
I have a couple meters and I ofter use my Simpson analog meter for certain situations where a digital meter is not fast enough to register an electrical pulse such as in a fuel injector system.

[Phil B]

Thank you for your comments and for your emphasis on safety.

[AntMan232]

Great instructable, I used a multimeter only this morning. I am 15, and a great fan of the AVO8 analogue meter, which I picked up for £2 at a car boot sale.

[Phil B]

Thank you and congratulations on getting a good bargain.

[80$man]

Excellent Instructable! 5 out of 5!
Everyone must have a multimeter, it is a very good learning tool!
I have got 'n poor/cheap one 'currently'... must find a replacement, any suggestions? 3-phase capabilities would be good...

[Phil B]

Thank you. I am not aware what makes and models are available in South Africa, although I am often surprised that the same things are often available in other nations that are available in the USA thanks to international marketing. In the USA the name Fluke is very well-respected for excellent meters of a professional grade. I wish I could be of more help.

[80$man]

I found a Fluke supplier in Cape Town, 35min away! Thank you for your reply!

[Phil B]

You are welcome. I hope it works out. Fluke meters are not inexpensive.

[ac-dc]

It is not true that corrosion could be a problem if it is not visible. For there to be enough corrosion to cause a problem it is progressed to the point it is very plainly visible and there is no need to check it with a multimeter as it is obviously in need of cleaning.

[askjerry]

Sorry ac-dc but I am a Senior CET with 30+ years of experience... and I have seen equipment fail because of a micron or so of corrosion build-up. The metal looked shiny, everything seemed normal... hitting the contacts with some emery cloth and a bit of denatured alcohol fixed the problem. (Or sometimes a rubber pencil eraser... keep one in your toolbox!)

Depending on the current going through a circuit... it may only take a tiny film to provide enough resistance to cause a problem... in some circuits the addition of as little as 1K ohm is enough to cause a failure.

Jerry
http://en.wikipedia.org/wiki/Electronics_Technicians_Association