THE BEST Multimeter tutorial (HD)

In this video I'm going to cover multimeters
and how to use them to measure voltage, current resistance and continuity. First up where do you buy a multimeter? Multimeters are everywhere. You can
get them at radio shack, sears, dollar stores wal-mart amazon ebay whatever is easiest for you. Okay so how do you choose which one to get? First up at the bare minimum make sure the
meter you're looking at can measure voltage, current, resistance and continuity. If you can find one that measures capacitance
and temperatures as well go for it. Unless you're working with some super special
application don't worry too much about accuracy. +/- 2% is usually good enough and even cheap multimeters these days will
be that accurate or better. Next the multimeter should have a digital
display not that old school analog crap. And it should have automatic ranging functionality
for as many things as possible. Trust me don't waste your time screwing around
with manual ranging. If you're too lazy to shop around just get
this one. Fifty bucks, it'll do everything you need and you won't outgrow it anytime soon.

Okay so now you have a multimeter – how do you
use it? Let's start with measuring DC voltages. First check the cables. Make sure the black lead is in the jack labeled
COM or COMMON. And once it's in there you'll never need to
take it out because the black lead always goes to COMMON. The red probe on the other hand is something
you'll have to pay very close attention to. If you plug it into the wrong track you will
blow a fuse in your multimeter.

We want to measure voltage right now so I'm plugging
the red lead into the jack labeled Volts not Amps. Next, set the dial to measure DC voltage. Touch the red probe to the positive terminal
of your device and the black probe to the negative terminal of your device and you should get a
voltage reading. If you get the wires backwards that's ok you'll
just get a negative reading on your multimeter and that's actually a good way to figure out
polarity. Now you can measure voltages in pretty much
any DC circuit as long as you're careful to not short anything out with the metal probes.

Okay let's move on to measuring AC voltages. Set the dial to the AC voltage setting and again
make sure the red lead is in the jack labeled Voltage. Touch the probes to the AC voltage
source that you want to measure and you'll get your reading. As long as you don't touch metal parts of
the probe or short them out this is perfectly safe. And as you'd expect there's no AC voltage coming
out of this DC battery. Measuring resistance is easy too. Make sure the red lead in the jack labeled
ohms for resistance and set the dial to the resistance setting. Here is me measuring the resistance of the
skin on my hand. Here is me measuring the resistance of a resistor.

And here I am measuring the resistance of
a speaker. Now you might be wondering if you can measure
the resistance of something in a circuit. Well unfortunately it most likely won't work. You're going to have to remove the resistor from
circuit before measuring it. Next let's talk about continuity. Measuring continuity basically just means
checking whether or not there's a good connection between any two points in the circuit. To measure continuity make sure your red probe is in
the jack labeled continuity, (or in my case resistance) and set the dial to the continuity setting. Yest that the continuity function is working
correctly by touching the probes together. Whenever there is almost zero resistance between
two points the multimeter will beep.

You can use the continuity function to check
if cables are internally broken or not. In the context of circuit boards, if there's a
good copper trace between any two points the multimeter will beep. If the circuit board is messed up, no beeps for you! Finally let's use our multimeter to measure
current. Set the dial to Amps setting. For almost all multimeters there's going to
be a separate jack just for measuring current. My multimeter has two. One for currents up to 10 amps
and one for currents up to 400 milliamps. I usually start out with the Amps jack but
if I need more accuracy I can switch to the milliamps jack later.

Now measuring current is a little trickier
than the rest of things. I can't just touch the probes and get an
Ampere reading. In order to see how much current is flowing through a
wire, I have to cut the wire, and splice in the multimeter in series with the flow before I can get a measurement. Here I have a simple circuit with a battery
pack, a motor and some wires. In order to measure the current drawn by the motor, I cut
the wire, splice in the multimeter, and now I can see that the motor is drawing
sixty milliamps. If I want more accuracy I can switch the milliamp
setting and now I can see that the motor is drawing somewhere between fifty seven and sixty
three milliamps. All right thanks for watching and have fun
with your new multimeter!