Browsing Tag

# source

In this video, you will learn
how to simulate circuits with dependent sources. In previous
chapters, we calculated mesh currents of this circuit. Lets
do it again by using Multisim. To add resistors, I click on the
” place basic” button of the components toolbox. Choose a
resistor and click OK. I single click on the workspace window to
place the resistor and close the components window as I use the
copy and paste method to add other resistors. I copy this
resistor by pressing control+C and paste 4 more resistors. Then
I select resistors R2, R4 and R5 and rotate them by using the
shortcut control+R. To add dc voltage source, I click on the
” place source” button, and from the “power sources”
family, select “DC_POWER” , click OK and a single left click
to place it on the workspace. To add a dependent voltage source,
click on the ” controlled voltage sources” family,
and select voltage controlled voltage source, click OK, and
single click to place it on the workspace, this time select
current controlled voltage source, and click OK to add the
other dependent voltage source, place it on the workspace and
close the component window. In my circuit diagram, the current
dependent voltage source is upside down so that the negative
terminal is placed on top. In Multisim I can flip a component
by right clicking on the component and select “Flip
vertically” . Alternatively, I can use the keyboard shortcut
Alt Y. I quickly do the wiring between components and place the
reference ground. For dependent voltage sources, the voltage of
the source is dependent on the current or voltage of another
part of the circuit. In Multisim you have to show this dependency
by using the correct wiring. For the voltage controlled voltage
source, the voltage of the source depends on the voltage
Vx across the R4 resistor. So I have to connect the input
rectangle of the source to R4. For the current controlled
source, the input rectangle is of type current, and this is
the current passing through R5 resistor, so I select this net,
and press the delete key to remove it. Connect the resistor
to pin number 2 of the input rectangle, and connect the
other pin to net number 2 of the circuit. In this way I
have placed the input of my current-controlled source in
the direction of the controlling current. So the current passes
through my dependent source. Wiring dependent sources like
this will make your circuit look very messy, and difficult to
debug if there is a problem. So here I use a different approach.
First I remove the wires between dependent sources and
controlling signal. Then I click on the menu bar, go to
” Connectors” and select “Global connector”. Add a
connector and name it Vx and connect it to pin number 1
of the R4 resistor. I want to connect Vx to this point, so I
add another connector here using the same name. You can easily
do this by copy and paste. When adding connectors, because the
net name will also change to the connector name, you will see the
name twice. If you don’ t like this, right click on the
workspace window, and in the sheet visibility tab, in the
Connectors section, un-check Global names, then click OK. I
go to place, connectors, and add another connector here. I
don’ t need to name it, because it is connected to ground, and
ground net is predefined in Multisim. So I only need to
select zero and click OK, then copy and paste it here. So Vx
nets are connected together without using any wire, and 0
nets are connected together as well. Lets go to the current
controlled voltage source. I go to place, connector and add a
global connector on the open pin of the R5 resistor, and name it
Ix+. I will then copy and paste it to the input port of the
dependent voltage source. When you use control V shortcut to
paste, before clicking on the workspace window to place the
component, you can use control R shortcut to rotate it before
placing it on the workspace. I place another connector and name
it Ix- to connect the other side of the input port to the
circuit. Now, the current passing through the R5 resistor
is also passing through the input port of the dependent
voltage source. Now that the wiring of the circuit is
complete, we have to change the component values before
simulation. You already know how to change the value of
independent sources and resistors, so I quickly change
the value of these components… Before changing the value of
dependent sources, lets review some important points related to
these kind of sources. Voltage controlled voltage source or
VCVS is a dependent voltage source in which the output
voltage is determined by the input voltage and gain. The
gain is the ratio of the output voltage to the input voltage. So
if you have a source like this and the output voltage is
mentioned as 3Vx. The gain will be the ratio of the output which
is 3Vx to the input which is Vx. Since the numerator and
denominator have the same units, the gain will have no unit. In
multisim, the voltage gain in indicated by E, and this is
the value you have to enter for voltage controlled, voltage
sources. In a current controlled voltage source or CCVS, the
output voltage is determined by the input current. The ratio of
the output voltage to the input current is called
Transresistance, and in multisim it is shown by letter H and
measured in ohms. So in our circuit, the transresistance of
the current-controlled dependent source is 2 ohms. Voltage
controlled current source or VCCS outputs a current value
which is set by the inputted voltage level. The output and
input values are related by a parameter called
Transconductance which is indicated by letter G and
measured in mho or siemens. And finally, current controlled
current source or CCCS outputs current which is adjusted or
controlled by the input current. Output and input currents are
related by a parameter called current gain which is indicated
by letter F in multisim. Lets return back to Multisim and
change the values of dependent voltage sources. If I double
click on the voltage controlled voltage source, there is a box
to enter the voltage gain value. I type 3 and click ok. Now I
double click on the current controlled voltage source,
and enter 2 for the value of Transresistance. I want to find
mesh currents of the circuit, so from the ” Instruments
toolbar”, click on the ” Measurement Probe” and add
three probes, one for each mesh. If you don’ t like the default
name which is ” Probe 1″ , double click on the measurement
probe, select the ” Display” tab and change the reference
Designator to i1 which is a more meaningful name for the first
mesh current. Also, I am only interested in current value. So
I click on the parameters tab, and only check the current
value. I click OK and do the same thing for the two other
measurement probes. The circuit is now ready for simulation.
I click on the “Simulation Switch” , and Multisim will
display mesh currents. If you compare the simulation results
with the values we previously found by solving algebraic
equations, you will notice that the results are
exactly identical.

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This is John Kohler with growingyourgreens.com,
today we’re on a field trip. We’re actually at a subscriber’s house, I’m actually
travelling here in Las Vegas, got an inquiry the other day or a couple of weeks ago from
somebody in Las Vegas about building raised beds and I answered some questions and I thought,
“Hey I’m going out to Vegas for convention, let’s check out and see if we could visit
this subscriber of my YouTube videos and check out what they’ve built, what they’re doing
and how they’re growing your food so you guys out there could see what each of you
guys are doing. And may be if I’m in your city, I’ll be stopping by real soon. So
I flew out here to Las Vegas, and I brought one of my prized plants with me, and these
are some tree collards and this was actually in my suitcase on the carry-on, and definitely
it’s cooking here in the Vegas heat, it’s not looking optimal, but you know what, it’s
still alive and hopefully, with any luck he can get this back and grow tree collards here
in Las Vegas. So, it’s a nice desert landscaping here in Las Vegas, interesting place to grow
some foods, let’s go inside and see what he’s got growing on.
So now we’re in the kitchen, and he’s growing in all the different spaces of his
house and right in his kitchen, his kitchen sink and stove and everything, and he has
a herb bed, herb garden right in his kitchen, all in these little planters with these fluorescent
tube lights that are really bright. Looks like a full spectrum, he’s got all kinds
of things growing, chives, basil, rosemary, dill, parsley, thyme, Greek oregano, cilantro,
and he’s placed magazines and other boxes so some plants will get closer or more far
away from the light depending on how tall they are. So Jason you want to tell us about
what you’re doing over here? Yeah, basically we just wanted a nice way
to just be able to grab our herbs real quick, my girlfriend’s actually a chef. So she
likes to use this stuff all the time. We’re still going to have hour herb garden, our
herb bed outside also, but this was just another fun way to do it just to compare indoors and
outdoors and see what happens. This is actually the first thing we set up here before we even
thought about putting beds outside. So, this was the beginning of it all right here, and
that’s pretty much it, I have to raise and lower the lights here every once in a while
depending on how high things grow, I have to switch the orders around a little bit,
but it’s pretty fun, and we can cut them and dry them, I have some organic liquid fertilizer
that I’ve been experimenting with, so, yeah that’s pretty much it.
Cool, looks good. So did you try to grow this without the light and how would it do, or
did it not work too well, or did you really think you just needed the light or could you
put it by a window, I mean this is in the middle of your house, so it’s not getting
too much ambient light as it is. Yeah it’s, I didn’t even try to grow it
without the light, because unless we have all the lights on it’s naturally pretty
dark in here. So, I think if I tried to grow something by that window, during summer it
gets so hot it might just get fried, so I figured this would be the most efficient area
to do it right here with the light, and this light is actually a two-bulb T5 set-up here,
and I think I got it from cyclegardeners.com, but it wasn’t that expensive, and it’s
working really well so far. Yeah the fluorescent bulbs, next to LED bulbs
are the most efficient, so you’re doing it the right way and those are T5s, so they
don’t use too much power. Now do you leave these on all the time or are they on a timer
system where they go on eight hours a day and turn off or?
They’re actually on a timer just like the ones upstairs are on a timer, these are also
on a timer, it’s on the other side, goes behind the couch, so they’re on for 16 hours
a day, and then it turns off automatically at night, and then when I wake up in the morning
it’s already on again, so. Alright, so we’re going to go upstairs because
Jason is growing in every area of his house from his kitchen to upstairs and let’s check
this out, his hallway upstairs. Man and check out those cool lights, I don’t know how
well this is going to show up on the video, but man, those are some LED lights. LED lights
are the most efficient lighting, and those are called glow panels. I’ve actually never
seen them in use, they look really cool, look at all those colors, and he has all these
plants, so he’s going to tell us more about what he’s doing over here. Alright Jason.
Alright so, basically this is something I just set up, I’m doing a few different experiments
here. This is [inaudible] matting, it’s sitting on this water-proof film which the
matting came with, and then I made platforms for it here. This is just some green Styrofoam
that you can get at any type of craft store, and then under that it’s sitting on just
these cake pans, they’re 50 cents at the grocery store, and then I use those as a reservoir,
so the capillary mat just lays in the reservoir there and soaks up the water, and then it
brings it up here, and this is moist, if there’s something that causes pressure it will stay
moist like this, you can feel the moisture there.
Oh wow, so right there where the plant was it’s really moist and you go over to here,
and it’s dry. That’s pretty amazing I never heard of this stuff.
So you pressed your finger along there and then all the water comes up. So basically
what want to… Wow, look at that you can draw your name.
Yep. You see I don’t know if they can see that
on the video, but I’m just pressing it and you can see where the water, and otherwise
it’s dry. That’s amazing. So my idea was, this is a three-inch ABS pipe,
I actually bought ten-foot lengths of this and cut them into four inch tall segments.
So what I’m going to do is I’m going to put them on here and fill them with soil,
put my seedlings, these are just pea pellets, I put the seedlings in here and I fill it
with soil, and then just let them sit here on the capillary mat, and then they’re just
going to stay just perfectly moist all the time, and then all I have to do once in a
while is just lift this up and fill the reservoir under there. And then, so it goes from the
pea pellets it goes into here, and it’ll just sit there for six to eight weeks. And
the benefit of this is that when I take this out to the garden, I can dig the hole, set
this in there, and just push it right through, and it comes out the bottom I don’t have
to disturb the roots or anything, just pull this out.
Right. Wow that’s cool. So these plants in here look like they’re really purple,
now they’re not really purple or anything, it’s just because the lights make it look
like a funny color right? Because these LEDs are like, I don’t know if you can see this
on the video, but they’re blue and red. And the idea for that is blue and red are
the primary spectrums that the plants use during different stages of the growth. During
the seedling stage it’s mostly blue, and then as they get older and closer to flowering,
it uses more red. So that’s why they’re so efficient, because it’s just the perfect
spectrums all the time. Each of these panels I believe is only 28 watts of power.
Wow. So this whole thing is like a little over
200 watts, where if you got just a HPS lamp or something, those will take up to 1000 watts
of power. So I figured if I was going to have this whole setup here, this would be the best
way to do it to save the most electricity. And you can see it’s pretty efficient, I
mean look at this, this is grown from seed under these lights, and it’s getting pretty
big now, it’s about ready to go outside. Yeah that’s really cool. So I see you lined
this with some foam stuff or just for some paneling, is that to reflect the light or
to just make sure your walls don’t get splashed or…
Yeah well it’s dual purpose, it’s to help protect the walls from splashing, but also,
I made sure it was flat white because flat white will reflect the full spectrum light
back into the plants, it’ll do a much better job than the brown paint.
How about putting tin foil or something to reflect the light? You think that would have
worked or a mirror? I actually thought about using Mylar, which
I have down there I’ll show you. It’s the same thing, the same type of film that
I’ll be using for mulch on top of my beds. It can reflect light but I figured for this,
not really necessary because I’m growing plants to full fruit here I’m just starting
the seeds. I see.
So I figured that would be efficient enough. Cool. Yeah the ambience of your lights, they’re
definitely really cool but how much did one of those set you back if you don’t mind
me asking? Each one, I got them from Amazon, each one’s
about a hundred, they change in price a little bit so it’s about anywhere between 114 to
120 or so. Yeah so I mean… Wow. Yeah \$100 light man. But definitely they’re
going to pretty much last forever, the LEDs really don’t burn out, really long life
expectancy and they’ll save you money in the long run. Really cool, I’m going to
have to maybe pick up one of those to play with. Alright great, thank you Jason.
So I hope you enjoyed part one, seeing what Jason is growing inside in containers in his
house underneath fluorescent and LED lighting. It’s really cool, I really enjoyed checking
that out. Stay tuned for part two in an upcoming episode where we’re going to go outside
in his backyard to check out his raised beds, and to see what Jason is growing in containers.
So you can do it too, it’s very easy. So once again this is John Kohler growingyourgreens.com,
keep on growing.