# [Guide] Common Multi-Meter Use

Discussion in 'General Electronics Discussion' started by Gryd3, Jul 7, 2014.

1. ### Gryd3

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Jun 25, 2014
There is nothing quite like giving advice or getting intel from someone using a tool that they do not understand how to use properly. This is nothing against the average joe who grabs a meter and starts poking, but with a little info, you'll be able to better understand how to use your meter and what the functions actually do!

Let's go all the way around the dial, starting from the lower left quadrant near the blue circle thing

This section is designated for measuring resistance, and will provide you with multiple ranges to measure.
The provided ranges are the highest value it can read at that scale and will function the same on analog meters. (Although you may find them harder to read off the bat)
When measuring resistance, the meter is quite dumb in the fact that it will attempt to measure ANYTHING you directly, or indirectly connect to both of it's probes.
If the part you want to measure is still connected to the rest of a circuit, you will end up measuring the desired part AND the rest of the circuit that is attached to it. To measure a resistor for example, you would unsolder one of the legs first, then connect your meter to both sides of the resistor. This will force the meter to go though ONLY the resistor if one of it's legs is disconnected.
When measuring resistance, it is always a good practice to disconnect your circuit from power first!
If you accidentally feed your meter voltage when it's expecting resistance bad things can happen.

The next section(s) are designated for voltage, and like the resistance section, will let you measure multiple ranges.
If you are unsure what kind of voltage to expect when measuring... don't touch the circuit! This typically requires the circuit to be live and connected to power. Higher than expected voltage could damage the meter, or your health.
When measuring voltage, the meter will tell you the difference in voltage from the black lead to the red lead. You can connect the leads on each side of a resistor and your meter will tell you how much voltage your resistor is dropping. You can connect the leads directly to the battery to tell if the supply voltage is appropriate.
Because measuring voltage usually requires a live circuit, great care should be given that you do not accidentally short out components with one of the leads, or cause harm to yourself. If you are just starting out, practice on small battery operated devices and seek some tutoring on safe procedures before you proceed to bigger items.

The next section is designated for current, and you guessed it, this section has multiple ranges as well!
If you are unsure what kind of current to expect when measuring... don't touch the circuit! Like voltage, this requires the circuit to be live and connected to power. Higher than expected current will damage the meter and potentially your health.
When measuring current, the meter will tell you mow much current is going though itself, and only itself.
You must put the meter directly in line with anything you wish to measure... want to find out how much current your entire project draws? Put your meter between a battery connection and the circuit. You can also determine how much current only a part of your circuit draws... those blue leds? Break your circuit so that you can put the meter directly in line with the electricity flow that powers the LEDs and behold, your meter will ignore the rest of the circuit and tell you how much current your LEDs draw.
Again, because the circuit will be live, you must take great care when taking these measurements. Please practice on smaller devices and seek assistance before attempting larger items.
*Never connect the leads directly to a power source or battery to see what it is capable of! This function will essentially turn your meter into jumper cables. Do not short out power supplies, or other items.

hFE is only included on certain meters, and is not nearly as common.
This function will measure the current gain of transistors when you plug them into that blue receptacle on the right.
More details will not be given in this section about that function.

The next little wiggly line, again, is not very common on entry level meters and would be used to determine frequency.

The last function, has a Diode symbol, and a sound wave... This function is used to test Diodes or continuity. Your meter will 'beep' at you when the leads touch, or when testing lengths of wire or connectors. Great simple tool as you dont often need to even look at your meter when your poking around.
This function should typically not be used in a live circuit, and like the resistance function is safer than voltage or current measurements. To test a Diode, please follow the same instructions as the resistance functions above.
*Please note that the continuity function is occasionally coupled into the resistance functions. Just look for the same 'sound wave' like symbol.

***Work in progress... Figured once it is cleaned up, it can be pushed to the Resources Section.

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Last edited: Jul 7, 2014
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2. ### shumifan50

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Jan 16, 2014
Not true for all circuits as it is possible to create a 2 rail supply from a battery.

Most of the meters I have had over the years allowed audible continuity testing at the resistor setting.

3. ### Gryd3

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Jun 25, 2014
Good call. Audio Amplifiers are a good example of this. I shall chop that our until I can word it better.

4. ### Harald KappModeratorModerator

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Nov 17, 2011
Have you considered polishing this article a bit and placing it in the ressources section?

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5. ### Gryd3

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Jun 25, 2014
Absolutely have.
I know it needs plenty of polish, as I was writing it in a bit of a hurry.
If it sits on here for a day or two it gives others a chance to take a peek and provide some insight and corrections.

6. ### shumifan50

579
57
Jan 16, 2014
I think most people know the basics if they own a multi-meter.
The areas where they fall down:
1. Exactly where to connect the meter to measure: a) resistance b) Voltage drop c) Current. Here I think simple circuit diagrams are required, especially highlighting what NOT to do with the probes, like setting the meter to measure current and putting the probes across the battery terminals.
2. Explain how to test a diode.
3. Explain how to test a transistor.
4. A brief introduction including the difference between AC and DC.
5. The meaning of the +/- when making a DC reading (polarity).
6. Ensure probes are plugged correctly: polarity, and correct socket as most meters have a different socket(s) for measuring current.

A section of DONTs.

Personally I would benefit from full explanation of the use of the Hfe setting.

7. ### Harald KappModeratorModerator

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Nov 17, 2011
From the questions I've seen here I think it is not so obvious as it seems. People tend, for example, to confuse voltage and current (your top 1).

8. ### Gryd3

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Jun 25, 2014
Sounds good shumifan50.
I'll put together a small safety section with some Dont's, and get some diagrams up.