hi So today we're going to be discussing
resistance what are resistors what a
resistor does in an electronic circuit
what is impedance what is the importance
of this how does this affect current and
voltage and that this this is one of the
most basic building blocks of any
electronic circuit so if you don't
understand how resistors work you're
pretty screwed so that's why we're going
to start with resistors now this is one
of those things where the Ed the
explanation that you get from a basic
Electronics textbook actually makes
sense or if you Google it and you look
at Wikipedia the way they explain it you
you actually can understand without
having had to go to college resistors
act to reduce current flow that is it's
just that simple a resistor is a passive
two- terminal electrical component that
implements electrical resistance now
remember what we were talking about
before we were talking about the
difference between voltage and current
voltage is the potential to deliver the
electricity whereas currents is the
actual flow of the electricity through
now as I said you cannot change the
current going through a circuit without
changing e the voltage or the resistance
so let's say you have a 12volt circuit
and you want to start getting more power
out of that 12vt circuit you need to
lower the resistance so I'll show you
how this works here with this basic ohms
law calculator now resistance is
something that's measured in ohms one of
the things that you're going to notice
about everything in electronics is that
all the people involved in electronics
they ego Maniacs they use their names on
everything so you know amps was named
after a guy named AER ohms was from the
guy who made ohms law who was named ohm
and so on and so forth so resistance is
measured in something called ohms so
let's say I have one .05 volts let me
just zoom in over here so that you can
see it even if you're at low resolution
so you have 1.05 volts and the
resistance is 10 ohms you're going to
get this many amps now if I lower the
resistance to 5 ohms you get more amps
if you up the resistance to let's say
1,000 ohms you get a lot less power you
get this many amps so the higher the
resistance the less current that you can
have flowing through a circuit and let
me show you how this works on a basic
schem I here so over here you have 3.42
volts on this side right now on the
other side of the resistor there's still
going to be 3.42 volts but you've
limited the ability for current to go
through that resistor so you're kind of
isolating what's on this side of the
resistor from what's on this side of the
resistor so this is a 3.42 volt power
rail let's say on the other side of the
resistor that this were to short to
ground on uh on this power lines it
without the resistor there you would be
shorting a main power line of the
computer to ground however since there's
a resistor here that limits current flow
and it's high in value it's 2 kohms
let's see the maximum amount of amperage
you can have on the other side so it's
3.42 volt power line here and that's a 2
kilohm resistor so we're going to go
back to our ohms law calculator so we
have a 3.42 volt line volt line and we
have a 2 kiloohm resistor so kilo is is
2,000 you can either CLI kilohms here
and go two and let's see so the maximum
amount of amperage you can have on the
other side of the circuit is
0.00006
which is like
0.0053 Watts which is negligible power
usage and this this is an important
concept to understand because over here
we're trying to create a signaling line
which is something that I'm going to
talk about in a future video in the
future video I'm going to talk about how
the resistor does it why we use
resistors to create data lines but
before you we get into any of the cool
things you can do with resistors you
have to understand a resistor basic
function a resistor function is that you
have less current on the other side of
the resistor than you do on the starting
side of the resistor so the amount of
current that can go through a resistor
is very limited without a resistor the
current would simply run through it as
fast as it could and you know and this
is this is not the desirable effect most
of the time so that's pretty much that
now impedance is a little bit different
so a resistor is you measure the
resistors resistance you know using the
word resistance so the resistance is
measured in ohms now impedance is a
little bit different impedance
is you're taking the entire resistance
of an of a circuit you're combining the
inductance the capacitance the
resistance every element of that circuit
and then you're giving that a value in
ohms so let's say I am measuring let's
let's go and measure something a little
bit more complicated here shall we so
let's go to a different part of the
circuit let's go to let's say U
7000 so let's say I
put uh let's say I put one probe of my
multimeter over here like the black
probe over here and I put it in
resistance mode and then I put the other
probe of the multimeter over here so you
know there are capacitors over here
there's a fuse there's a current sensing
resistor and there's an inductor so
there are a lot there's a lot of
different stuff going there's a lot of
different things going on here you
wouldn't call that the resistance of the
circuit you would call it the impedance
of the circuit because there's a lot
more going on there than just basic
resistance but impedance can be measured
in ohms the same way that resistance is
measured in ohms and that this is
another thing that's important to
understand here is that you can
tell when a circuit is working the way
it's supposed to or for example let's
say that this thing is destroyed right
you may get a different value when
measuring the impedance of that circuit
than you would if this was working so
understanding how resistance and how
impedance measurements work and also
keeping a little a little Excel sheet
for yourself of when a circuit is
working of what its impedance to ground
is of what the impedances between
different points in a circuit is on a
working board can help you troubleshoot
a bad board so instead of having to you
know replace every single component and
test every single component in every
single part of the circuit you could
just make quick measurements to narrow
down what's actually going on so that's
what a resistor is a resistor simply
resists electrical flow it simply
resists the current going from one side
to the other so the voltage will be the
same it doesn't matter if you have a 1
million Ohm resistor and you have 12.6
volts on one side you're still going to
have 12.6 volts on the other side but
the current will be limited through the
resistor because the resistor is
resisting the current flow