Introduction: EVERYONE Needs a Multi-Meter

Picture of 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?

Picture of 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. 

Step 2: So, What Can a Multi-meter Do?

Picture of So, What Can a Multi-meter Do?

See the first photo. You can test common batteries, but that is only the beginning of what you can do with a multi-meter. Set the selector to DC volts. Notice the symbols for AC (alternating current) voltage and for DC (direct current voltage) as highlighted by the yellow text boxes. Batteries use only DC voltage.  Set the selector to the proper range on the DC scale. Household batteries like AA and AAA are rated at 1.5 volts. On this meter, select the 4 volt range on the DC scale for common batteries. If I were testing a 9 volt battery with this meter, I would need to move the selector to the 40 volt range.  

(This meter has an ON/OFF slider switch. Many meters turn on when the round selector switch is moved to any setting range. OFF is at the top of the selector dial on those units. Meters have internal batteries. Turn the meter OFF when finished to save the batteries. Many meters switch themselves off automtically after a few minutes.)

See the second photo. Touch each end of the battery with a probe.  Ideally, the red probe touches the "+" end of the battery and the black probe touches the "-" end of the battery, but in practice it does not matter for this purpose. A minus (-) sign will appear in front of the numbers if the red and black wires are reversed when testing the battery. You are interested in only the numbers. A 1.5 volt battery is "dead" when it registers 1 volt or less. If a device does not work, but the 1.5 volt battery registers (for example) 1.38 volts, a new battery will not make it work. There is another problem to be solved. A 9 volt battery is "dead" when it falls to read about 7.5 to 8 volts. But, when a battery is "dead" also depends on the application. I use a 9 volt alkaline battery in a wireless microphone. I have learned by experience that a battery with a voltage below 8.5 volts will not last through a one hour church service.

Shown in the photo are several types of common batteries: a 3 volt camera battery, a 9 volt "radio" battery used in smoke detectors and other things, a button battery used in watches and other instruments, and a common AA battery. In this test the AA battery registers 1.59 volts, which is new in condition.

There are dedicated battery testers you can buy, but a multi-meter costs about the same and does so much more. Some multi-meters come with a battery test function built in. Such a function adds a resistance to test the battery under a load similar to what might be encountered in a device. Here is a way you can add a battery test function to a meter you already own.

Step 3: Your Car Battery

Picture of Your Car Battery

One morning you turn the key in your car, but the motor turns over too slowly to start. You suspect the battery may be dead. Set the meter selector to 15 volts DC or more. Touch the meter probes to the terminal posts on your car battery. The meter will read 12 to 13 volts, but you want to know what the voltage reading is when the battery is under a load. Have someone turn the key while you watch the meter. If the meter reading drops to around 9 volts or less, you need to charge the battery and see if that solves the problem. If you still get a reading of about 9 volts under load after a sufficient period for charging, you probably need a new battery for your car. 

Step 4: Corrosion?

Picture of Corrosion?

See the first photo. Your car battery may be in good condition, but the starter still barely cranks the engine. The problem could be corrosion at one or both of the battery terminals. Sometimes you will see white or blue powder around the terminals, but often the corrosion is not visible. The photo shows an old-style battery terminal.  If your car (or motorcycle or riding lawnmower) has this type of terminal, see the text boxes for where to place the voltmeter probes. Set the voltmeter to a DC setting slightly in excess of 12 volts. Have a helper turn the key to crank the engine.  If the battery connections are good, the voltmeter reading should remain at zero (0).  If the battery connections are corroded, they will provide a high resistance, perhaps even an open circuit, and current will try to go through the voltmeter as an alternate route. The voltmeter reads the difference in voltage between one probe and the other. That means the voltmeter will show a reading equal to the voltage of the battery.  Clean or replace the battery terminal by taking it apart, dissolving the corrosion with baking soda in water, and scraping the parts of the connection. If you use your multi-meter just once for this, you will have saved enough money to pay for it.

See the text boxes in the second photo. The newer side post battery terminals are now more common than the old-style shown in the first photo. Much of the terminal is covered with insulation. One meter probe touches the terminal's bare metal bolt. The other probe can touch a straight pin pushed through the cable's insulation. 

(The first photo is from Bing Images.)

Step 5: Light Bulbs

Picture of Light Bulbs

Is your light bulb burned out, or is there a problem with your lamp? The first test is to check for a circuit through the light bulb. Use a low resistance or a CONT setting. This test will not work with the compact fluorescent bulbs, nor with fluorescent tubes. Those do not have a continuous conductor running through them, like an incandescent light bulb.  Rather, they are filled with a gas that becomes a conductor when exposed to a high voltage electrical charge. 

If the bulb tests good, some further checks on the lamp socket are necessary. See the second photo. Set the meter to the 400 volt AC selection. Touch one probe to the side of the bulb socket.  Touch the other to the tip at the bottom of the socket. The meter should read about 120 volts. (Note: I live in the USA where most electrical outlets operate on 120 volts. Heavy duty appliance circuits [electric stoves, clothes dryers] use 230 volts. In many other parts of the world the standard voltage in household electrical systems is 230 to 240 volts. Adjust the readings you expect according to the normal voltage provided in your locale.)

You may find the expected voltage in the bulb socket and also the bulb are good, but the lamp still does not light. If the socket is older, the contact tip at the bottom of the socket may have lost its springiness and it may not make dependable contact with the center tip of the bulb. Use a popsicle stick to lift the tip. If you can be sure there is no electrical power to the socket, you may use a screwdriver. Then screw the bulb into the lamp socket and it should work. In time you may want to have the lamp socket replaced, but it can work this way for a long, long time.

Step 6: Fuses

Picture of Fuses

Many devices use fuses, from your automobile to your household air conditioning system. A fuse is an electrical conductor designed to fail when a pre-determined threshold of current is present in the circuit. Their purpose is protect the rest of the circuit from a current load that would destroy it. 

Sometimes fuses are out in the open where they are visible. Sometimes they are under a cover marked "Fuses." Sometimes they are inside an appliance with no notice of their presence. This is true of some microwave ovens and some television sets. Open the case and look for a small cartridge fuse like the one shown in the photo. The fuse will usually be near where the electrical cord comes into the appliance. You may have thought you need a new microwave, but the real problem may be only a small fuse costing less than a dollar. Sometimes there is a more serious problem that will cause a new fuse to "blow," too. But, more often, the old fuse simply became weak or "blew" because of a momentary electrical surge. If your multi-meter saves you from replacing an appliance that failed due to a blown fuse, your meter will have paid for itself many times over. 

It is always good if you can have extra fuses available for whenever one needs replacement. When you need to buy a fuse, take the old fuse with you to the store so it can be matched. Fuses come in a variety of physical sizes and types. It is important to replace a fuse with one exactly like it. Some fuses are available at your local hardware or building supply store.  Some, like small cartridge fuses similar to the one shown in the photo, are available only where electronics parts are sold, or on-line. Identifying numbers are imprinted on the shiny metal end caps.

The fine wire in cartridge fuses is often so fine that it is difficult to see with the unaided eye. Some fuses have a solid body that blocks vision. When testing fuses set the multi-meter to CONT. for continuity. Touch the probes to the ends of a good fuse when on this setting and you will hear a shrill tone indicating there is a continuous circuit through the fuse. No sound means a bad fuse. The words "continuity" and "continuous" are purposely related.

WARNING: If you open the case on a television or a microwave, be careful not to touch components other than the fuseholder. There are parts that retain a high voltage electrical charge. It is not likely you would touch these, anyway; but, if you did, they can kill.


Step 7: Your Air Conditioner Unit

Picture of Your Air Conditioner Unit

Air conditioning systems always seem to fail during the hottest, most miserable weather. No one wants to spend a muggy night trying to sleep with no air conditioning. If the problem is only a fuse, your meter can save you the cost of a service call by a technician, and you can have your system up and running again before the house has even warmed up inside.

Your air conditioning system may have more than one set of fuses protecting it. There may be a set of circuit breakers in your main electrical panel. Check to see that the circuit breaker toggles have not moved to the "off" position due to a sudden overload. Go to the air conditioner unit outside your house. Look for any cable conduits (metal pipes, some flexible). Follow them with your eye and look for any metal boxes that might contain fuses. The fuses will likely be mounted in a fuse block that can be pulled from the box. Use the continuity setting to check the fuses. The first photo shows a control box near our heat pump/air conditioner. It looks like it might contain fuses, but it contains only a disconnect switch.  

See the second photo. It shows the inside of the fuse box that controls our air conditioner. The yellow text box contains information on the ON/OFF switch. I overlaid the photo with capital letters as markers. Those in red make a "hot" circuit even when the switch is "off." Keep your hands safely away from these terminals.

Set the meter to the 400 volt AC setting. If you place one probe on A and the other on B, the meter should read about 230 volts. That is true whether the switch in the box is "on" or "off." Place one probe on A and the other on C. The meter should read about 115 volts. Place one probe on B and the other on C. The meter should again read about 115 volts. Readings between F and C or G and C should also each give a reading of about 115 volts when the switch is "on." These readings indicate the fuses are good. With the switch in the "off" position, readings between F and C or G and C should be zero volts.

If you wish to check the fuses without them being electrically charged, move the switch lever to the "off" position. Set the meter to CONT. Touch one probe to D and the other to F. You should hear the meter's shrill chime tone. Now place one probe on E and the other on G. You should hear the tone again. This also indicates the fuses are good. If one of the fuses does not test good, be certain the switch is in the "off" position. With your fingers or a pair of pliers or a wooden stick to pry, remove the bad fuse. Take it with you to a hardware or building supply store and get a replacement. Use a fuse. Do not use a piece of metal, a piece of copper tubing, or a wire with alligator clips to bridge the space for the fuse. In the days when most homes had screw-in plug fuses some people sometimes put a copper penny behind a blown fuse when they did not have a new fuse. Then they often forgot about the penny. Pennies do not burn away like a fuse does when there is an overload. Pennies used this way often caused house fires. There was a frequent saying that, "The words 'In God We Trust' were placed on pennies for the benefit of those who use them as fuses."

Step 8: The Electric Clothes Dryer Does Not Dry.

Picture of The Electric Clothes Dryer Does Not Dry.

The wet clothes in your dryer are still wet after running for the full cycle. The drum turned. The dryer went full cycle. What could be wrong? First check for a clogged filter or vent pipe. If those things are good, the problem may be electrical, and a multi-meter can help you find and fix it.

Dryers operate on two different circuits at two different voltages. The motor that turns the drum works on 115 volts. The heating element works on 230 volts. The electrical outlet behind your dryer that powers the dryer looks like this. 

Set your meter selector to 400 volts AC. Put one probe into the "A" slot. Do not touch the other probe, but insert it into the "B" slot. The fit may not be tight. You may need to wiggle the probes to touch the metal inside and get a reading on the meter. The meter should show 230 volts. "C" is the neutral wire. "D" is the ground wire. Place a probe into "A" and the other probe into "C" or "D" and the reading on the meter should be 115 volts. The same should be true of a reading between "B" and "C" or "D." If you do not get these readings, check to be sure one circuit breaker or one fuse is not blown. There is the possibility that the dryer's heating element could be burned out, but that is not as likely. You can access it from the back of the dryer. Remove a cover over its terminals. Be sure the power to the dryer is disconnected. Use an Ohms setting on your meter and check for an open circuit. Testing an oven element in your stove is very similar. Remove the screws that hold the element in place and pull it from the oven. Do a resistance check on the two terminals.

(The photo is from Bing Images.)

Step 9: Electrical Outlets

Picture of Electrical Outlets

Sometimes you need to check an electrical outlet, or replace it. See the text boxes in the photo. Set the meter to 400 volts AC. Place a probe in the "hot" slot and another in the neutral slot.  The meter should read about 120 volts. Place a probe in the "hot" slot and in the ground slot. The meter should read 120 volts. Place a probe in the neutral slot and in the ground slot. The meter should read zero volts. Check outlets with your voltmeter before removing the cover and beginning to work on them. You want to be certain the power is "off."

Step 10: Cords and Other Things

Picture of Cords and Other Things

I have added alligator clip attachments to the probe ends on my meter. They are a very handy accessory I got at Radio Shack. They are like an extra hand. 

This toaster works well, and the meter shows a resistance reading due to the heating element inside the toaster. This is normal and good. This test could indicate there is a break in the circuit within the toaster. Further testing would be necessary to determine which part of the circuit is defective. Then a decision would need to be made as to whether the appliance can be repaired and whether it is worth the effort.

Whether it is a toaster, or a phone charger, or a power cord for a computer; cords often fray internally within an inch or two of the plug. This is very understandable. That is the area of the cord that is frequently flexed back and forth. If something, like a phone charger, works some of the time, but not at other times; attach the meter with a resistance scale setting. Gently flex the cord back and forth near the plug end. Make fairly sharp bends. Watch the meter reading to see if it fluctuates between a normal reading and no connection. If it does, ask someone with a soldering iron to cut the cord back and reattach the plug end for you. 

Step 11: Lightning and Your Telephone

Picture of Lightning and Your Telephone

This is an illustration of what is possible with a meter.  It is not intended that most users would ever do this. Yet, many on Instructables experiment with LEDs (light emitting diodes), and it would pertain to that.

During the 1980s I was the pastor of a church in a rural setting. Lightning sometimes struck the utility company's power distribution lines and jumped to telephone lines running into our building. Once our telephone would not work. Twice the phone answering machine would not work. I was able to use my meter to rescue the telephone. I was also able to rescue the answering machine once, but not the second time. After the second strike we added a surge protector and had no problems after that.

See the first photo. The selector is set to the diode checker. Diodes are one way electrical valves and are very sensitive to surges of electrical current, especially with things like lightning. The arrow with a line across the arrow point is the standard symbol for a diode. Not every meter has a diode checker setting. Because diodes are very sensitive to current overloads, the diode checker limits the current in amperes that flows through a diode while testing it.

The second photo shows the circuit board from a telephone. The yellow text box identifies a bank of four diodes. Although diodes can come in many sizes and shapes, those commonly used on circuit boards like this one are small black cylinders about 5/16 inch long and about 5/32 inch in diameter. At one end is a gray band. A wire runs out of each end of the diode.

You may notice the probes do not look anything like the probes you have seen before.  This is another accessory I got at Radio Shack. It is a set of clip on probes designed to grasp the small wires of electronic parts to make getting an accurate reading easier.

When testing a diode, you are looking for a relatively high current reading when the red and black leads are attached one way, but a relatively lower reading when the connections are reversed. Note that the red probe is above the black probe in this photo and the reading is 1.585.  See the third photo. The black probe is now above the red probe and the reading is one-third the previous reading, which is considerably lower. These readings are the sign of a good diode.  

Often a diode can be checked without removing it from the circuit. Sometimes the readings are confusing. Chances are current is feeding through some other electronic component to cause an undependable reading. Then it becomes necessary to desolder one of the diode leads to isolate it from the circuit for accurate readings. 

In the lightning incident I mentioned, there were only a couple of diodes. One of them failed its test. For less than a dollar I was able to replace the defective diode and the phone was good ever after. At the time a new phone was about $20.

See the fourth photo. It is a Maglite flashlight that now has one of their LED bulbs. It quit working and I needed to know if the LED was still good or not. I did a diode check with my meter and discovered the switch was the problem.

Step 12: Reading Amps. (current Draw)

Picture of Reading Amps. (current Draw)

Although often used interchangeably in this Instructable, and wrongly so, "current" and "voltage" are actually different from one another. Voltage concerns the pressure at which electrons flow, like water pressure in a pipe.  Current (amps. or amperes) deals with the volume of electrons flowing at the operating voltage. A device may appear to work, but makes an unusual noise or quickly overheats. A check of the amps. drawn by the circuit can tell you if there is a problem, even though it will not identify the exact problem.  

First, check the device specifications.  Look for a plate or label on the back or bottom of the device. It may tell you the device is designed to draw (for example) 2.3 amps. at 120 volts. Or, it may tell you the device uses 276 Watts at 120 volts. (Watts equals volts multiplied by amps., so divide Watts by volts to determine the proper amps.) If this device were found to draw (for example) 4.5 amps., you would know immediately something is wrong.

Reading amps. is different from reading voltages. Voltage readings are the drop in electrical "pressure" across two points in a circuit, or a whole circuit. The meter is not part of the circuit, but reads what happens across or between two points in the circuit.  When reading amps, the meter must become a link in the circuit, just like a link in a chain. See the graphic showing how you can make a sandwich with two conductors and a piece of plastic between them. This sandwich can be placed between two batteries in your device to see what the current draw is. The alternative is to break the circuit by cutting a conductor and connecting the meter to the ends of the cut conductor. You would need to reconnect the cut connector when you are finished. Set the selector for DC amps in the desired range.

You may need to change the holes into which the probes connect on the meter. See the second photo.

Step 13: Shocking, Simply Shocking!

Picture of Shocking, Simply Shocking!

My father had a small electrical business when I was in high school.  I was often his helper. Many of his customers lived on farms. A frequent complaint was a tingle (mild electrical shock) when taking a shower bath. Invariably, there had been a lightning strike nearby recently, and the lightning surge had shorted an electric water heater element to ground through the water inside the water heater tank. Turn off the power to the water heater at the circuit breaker. Remove the cover plates over the heater elements and pull the fiberglass insulation back. Disconnect the wire from one of the terminal screws on the heater element to isolate it from any possible feedback through another part of the circuit. This is to avoid false readings. Set the Ohms scale to a high range. Look for this symbol: Ω to identify the Ohms or resistance scale. Touch one probe to one of the heater element terminal screws. Touch the other probe to bare metal on the side of the water heater tank. If the element is not shorted to the water inside the tank, the meter reading should indicate an infinite resistance (no current flow, an open circuit).    

A few years ago we had a neighbor who avoided having grandchildren visit because anyone who touched the built-in kitchen stove received a mild electrical shock. I set my meter to an AC voltage setting in the 150 volt range and placed one probe on the chrome oven handle and one probe on a sink faucet. My meter told me the electrical current registered about 40 volts AC. It took me some time, guess work, and checking; but I found someone had disconnected the thin green wire that connects the metal frame of the stove to that home's grounding circuit. When I reconnected the wire, the stray voltage disappeared. The green ground wire was located on the back of the oven.

Step 14: Another Use From the Past

Picture of Another Use From the Past

The person to whom this Instructable is geared will not likely do this, but it is an example of yet another helpful use for a multi-meter. We parked our car in a store parking lot. When we left the store, it would not start. The battery had failed because the battery post had become disconnected from the internal circuitry of the battery. When I installed a new battery there were immediate signals that all was not well with the car's charging system. I did some reading in my auto manuals. I learned a poor battery connection can cause the rotating field of the alternator to burn out. The resistance of the field coil (rotor coil here) should be 1.5 Ohms. That is tiny. I set my meter for a very low Ohms reading, touched the probes to the slip rings, and found there was far less than 1.5 Ohms of resistance. The wires in the rotor coil had burned their insulation and shorted. This did not save any money, but it saved time for me. Suddenly I knew what the problem was and knew what to do to fix it. I also needed a new alternator. Without a good multi-meter, I would have only continued to guess about the problem.

(The photo is from Bing Images.)

Step 15: Auto Ranging Meters and Reading the Meter

Picture of Auto Ranging Meters and Reading the Meter

It is easy to forget to set the meter to the right range for the type of reading you will be making. With an analog (needle indicator) meter, that could be fatal to the meter. Some digital meters are "auto-ranging." That means the meter automatically makes the right setting. My meter has circuit protections built into the meter. Part of this is two fuses designed to "blow" before the circuitry can be harmed. I try to keep extra of these fuses on hand, just in case. See step 16 for a photo with the location of the fuses.

On my meter the digit "3" indicates an open circuit (= no path for electrical current). If I am using the Ohms (resistance) scale, the digit "3" appears until I attach the probes to the device I am testing. Sometimes the digit "3" remains when attached to a device known to be good. There should be an actual reading, but the reason there is not is that I have the meter set to an incorrect range. The device I am checking may have (for example) a resistance value of 12,500 ohms. If the meter is set to a range too low, perhaps to the 4K range, the digit "3" will appear on the display. If I move the selector to the 40K range the meter will suddenly give the reading I am seeking. I try to remember to begin at a very high range that may not give me as many numbers in the reading as I hope to see. Then I move the selector to lower range settings until I see the number of digits in the reading for the accuracy I need.

Step 16: Accessories and Features

Picture of Accessories and Features

I have already mentioned two accessories available for my meter: insulated alligator clips and spring clips for grasping electronics component wires. The photo shows a telephone pigtail that makes connecting to the telephone lines for a voltage check easy. I used my alligator clips to connect to the red and green wires on the pigtail. If all is well, the voltmeter should read about 50 volts DC. See my earlier Instructable. This can be a big help when you are reporting a service outage. The pigtail has two other conductors. I taped them so they would not touch anything and create a short. Note: 50 volts DC is low enough that you can touch the bare wires without a shock. Still, do not stand in water when doing this. Water multiplies the danger.

Sometimes you need an extra hand. Multi-meters come with a fold out stand on the back of the meter. These usually can also be flipped up to function as a hanger for the meter. This frees both hands for manipulating the probes, especially if the voltages could harm someone.

See the text box in the photo for details on the Hold button. Sometimes you may be able to reach terminals with the probes, but may not be able to read the meter. If you can manage to press the Hold button and release it, the meter will freeze the reading so you can move and see what the meter recorded.

Step 17: User Serviceable Things

Picture of User Serviceable Things

Very little on a multi-meter requires attention. There is a door or plate on the back that opens by removing a few small screws or with a snap that can be opened with a fingernail. Inside are the batteries that power the circuits in the meter. There may also be some fuses. Very cheap meters may not have fuse protection.

When the batteries grow weak there may be a weak battery indicator on the display screen. You will notice the display numbers grow more weak and difficult to see unless viewed at just the right angle. If the meter will not be used for very long periods of time, it is a good idea to remove the batteries so they do not begin to leak and ruin the metal tabs in the battery compartment. This meter uses three AA batteries. Many meters use one 9 volt battery. Notice that this meter has two fuses. One is a fast blow fuse designed to protect the meter from the wrong setting on the meter's selector switch. I have a few extra fuses in a small plastic bag. The bag fits into the battery compartment. Notice that the fuse specifications are also molded into the plastic case.

Step 18: Additional Resources

Picture of Additional Resources

If you want even more ideas for how to use a multi-meter to solve problems at home, get a copy of this book. A similar book appeared after this one. I bought this about 20 years ago and it is very helpful, although it tends to go into a next level beyond this Instructable with more applications and more detailed tests. And, a new edition of this book is available again at Radio Shack stores. 

Do not be cavalier when working with electricity. Take many precautions. Check and double check to be certain a circuit is not live. Many important measurements that tell you about the health of a device can be made without power to the circuit, other  than the small batteries inside your meter. Using a multi-meter can help you fix problems safely and quickly without waiting for an expensive service call by a technician. 


maleD (author)2016-07-18

Helpful tip! I have my own multimeter which I am very satisfied with just don't know how to use, this is a good read. I bought the unit at and used the code 10SPECIAL to avail 10% off.

StefanL3 (author)2016-03-22

Incredibly helpful...thanks!

Phil B (author)StefanL32016-03-22

Thank you for your comment. I am glad it is useful to you. A multimeter can save the owner a lot of money quickly. Also, you can use a multimeter with benefit for things where you feel safe and comfortable. When you get to something that makes you nervous, call in someone with more knowledge and experience.

aoke (author)2014-04-06

Thanks for your great article friend, i get new information, new ideas to do somethings, i hope you will share again, i keep waiting for next post, thanks.

Phil B (author)aoke2014-04-06

Thank you.

spylock (author)2013-09-24

You are right,and as far as carrying one in the purse, ladies who may not be so bold as to carry the larger meters in the pocket book may be interested to know that Radio shack makes a nice little meter that is small around 4x3x1/2.It folds in half, it is kinda expensive,I paid about 30.00 for one a few years back as I needed it often for work,and it was small enough to carry in my shirt pocket.Very good advice,for all ,good thinking.

Phil B (author)spylock2013-09-25

Thanks. The photo of the meter sticking out of a woman's purse with her cosmetics nearby was a little tongue in cheek joke. I ran it past a lady preschool teacher I know and she thought it was pretty funny.

I have seen some pocket meters like you describe. They would be great for what you describe. My brother gave me a basic Radio Shack meter that does not fold, but is about 3/4" x 1" x 6" with an insulated fixed probe on the front end and a wire lead near the front end. It is small enough to carry in a pocket case for eyeglasses. I have often taken it with me when I travel.

spylock (author)Phil B2013-09-25

Sorry I didnt catch on,the reason I took it serious is because my mothers purse had a small screw driver set,keychain type multi tool,a credit card tool with many uses,well you get the just of it.She didnt however have a meter as she was scared of electric;its just my Pops and myself now,and we ran a small plumbing/drain cleaning company from 1987-2010.We are some do it ourselves kinda people.It is kinda funny now that Ive thought about it,but I think man and woman alike should at the very least carry a pocket knife,and I like your instruct.I hope ladies read it and take it to heart.

Phil B (author)spylock2013-09-25

There are probably a few ladies adventurous enough to use a meter, even if for a few basic things. Imagine a woman in a group including a few men. The TV remote does not work. She removes the batteries, pulls a VTVM from her purse and tests the batteries. In a few minutes the remote is working again. Some will admire and respect her. Others will feel outclassed and hate her.

spylock (author)Phil B2013-09-25

I would be of those who respect her for sure,I respect anyone who will at least take a wack at it,and those who dont know how,but ask get my respect as well.

Phil B (author)spylock2013-09-25

My wife was the first woman I ever met who knows what a wood lathe is. Her grandfather had one. I had bought one by saving my allowance in junior high. I still have it almost 55 years later.

spylock (author)Phil B2013-09-25

My mother knew what a forge was,and when I was making mine out of an old wheel hub,she told me that a wheelbarrow made a much better one,course I didnt know she even knew what a forge was,but her grandmother who raised her was a Hatfield,and up in west Virginia they had to make do.Ill tell you Phil,woman folks will surprise you sometimes,wont they?

J,R,D, Ltd (author)2013-04-09

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 (author)J,R,D, Ltd2013-04-09

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.

fretted (author)2012-10-30

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

Phil B (author)fretted2012-10-30

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 (author)Phil B2012-10-31

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 (author)fretted2013-01-19

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 (author)Phil B2013-01-21

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

Phil B (author)fretted2013-01-21

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 (author)fretted2013-01-21

lol np = no

vanwazltoff (author)fretted2012-11-04

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 (author)fretted2012-11-04

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

The nerdling (author)2012-12-27

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 (author)The nerdling2013-01-19

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

jchamberlain (author)2012-12-24

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 (author)jchamberlain2012-12-25

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 (author)Phil B2012-12-25

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.


Phil B (author)jchamberlain2012-12-25

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 (author)2012-11-05

Just the title made me proud to own one :)

Phil B (author)darman122012-11-20

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

tim_n (author)2012-10-20

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 (author)tim_n2012-10-20

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 (author)2012-06-20

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

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 (author)Nano_Burger2012-10-20

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 (author)Nano_Burger2012-06-20

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 (author)2012-10-16

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 (author)raziz2012-10-16

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.

tridecagon (author)2012-09-26

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

ac-dc (author)2011-05-19

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.

Phil B (author)ac-dc2011-05-19

I am sure I remember reading that not all corrosion is visible. Before responding I did a search and found someone had problems with corrosion he could not see without removing the battery connectors. I have found the newer side post terminals can be quite corroded, but the corrosion remains covered and not visible from a quick glance under the hood.

79spitfire (author)Phil B2011-05-20

This is true, corrosion can "hide" in the contact areas between the terminal and post. What your doing is called a "voltage drop test". It's a quick and easy way to locate where a bad connection is raising havoc. There are several good videos showing how to use a voltage drop to solve real world problems, including cars that won't start with battery terminals that look clean!

Phil B (author)79spitfire2011-05-20

Thank you. I assume the videos are at YouTube. Is that correct?

79spitfire (author)Phil B2011-05-20

Yes, and they scattered about the web as well. Several auto manufactures are teaching their factory techs how to use voltage drops to more effectively repair cars and especially computer circuits in cars.

Phil B (author)79spitfire2011-05-20

I first became aware of the voltage drop test for auto battery connections testing from an old Motor's Auto Manual. That particular manual was published in 1969. Thanks.

ElectroFrank (author)Phil B2012-08-19

I once replaced my car battery that seemed to have expired, with very poor response from the starter motor.  But the new battery made no difference.  

After carefully tracing volt drops, I discovered substantial corrosion on the engine block where the battery ground cable terminal bolted to it.  

Just cleaned and greased, and no more problem.   Thinking about it, two different metals, plus a bit of moisture and a current, is a beautiful recipe for corrosion. 

I always grease or oil nuts and bolts and electrical connectors when reassembling things, particularly on my car, both for preventing corrosion and ease of extraction the next time.

Phil B (author)ElectroFrank2012-08-19

Your information is very good. I knew a man back in the 1970s who had spent over $100 to have a bad ground discovered and fixed. To complicate things, grounding terminals are often hidden under layers of other things. Thank you for the important reminder.

NaturalCrafter (author)Phil B2011-05-20

You are right. I have watched my husband working on a small circuit board that would not work he took out the battery and used very fine sand paper on the contacts, suddenly the thing just stared working right again. This always amazes me. I have to say my first experience helping to fix something was my grandmothers toaster would not work. My dad took out his meter, tested good, then tried another plug and looked inside and scratched his head. The two copper leaf contacts were only very slightly brown like a dull penny. I offered maybe an eraser on the contacts. So he chuckled and let me try it. Then when we plugged it back in and it lit up, he was amazed...My dad was an electrical engineer...only time I ever got over on him as he was sure it was a broken internal

ac-dc (author)NaturalCrafter2011-06-12

Apples and oranges, brass and copper especially degrade much more resistively and faster than lead, which is why lead is chosen, BUT we were speaking about visible corrosion too - brown like a dull penny is considered visible corrosion on copper.

Phil B (author)NaturalCrafter2011-05-20

If you are familiar with electrolytic capacitors, those are made by allowing an oxide to form on one side of the aluminum foil. It serves as an insulator and has the advantage of being thinner than paper or mylar film. It is a powerful reminder that oxides look like conductive metal, but actually insulate. Your father's experience with the toaster shows we look for what we expect to find, and sometimes that blinds us to what is.

About This Instructable




Bio: I miss the days when magazines like Popular Mechanics had all sorts of DIY projects for making and repairing just about everything. I am enjoying ... More »
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