Um, so it's completely unpowered right
now. If we were to plug it in, power
would come in through here regardless
of whether the relay was turned on or
off. This transformer will pick up
signal from it so that is one function that i tried
to make sure we would have is that even
if the relay wasn't allowing power to be
supplied to the appliance, the entire box
will still be powered. And I was able to
achieve that so that's kind of nice.
Um, this transformer right here will
supply 12 volts of dc power to the
board, which is used by the Arduino Nano
over here.
And the relay,
the relay is a 12 volt relay so that was
perfect. The Nano, however, um
is not 12 volts. I think it requires
about 5 volts, however, it does have a
built-in 20 volt voltage regulator in it,
which was kind of nice. So I was able to
give it 12 volts
uh with no hassle.
Then the Arduino
has a 5 volt out pin that it powers the
Bluetooth module the current sensor
which is kind of hidden under here, let
me see if i can get it. It's that black
square down there that says "a" on it.
And then this blue thing over here is
our thermocouple.
So yeah, those all get powered send the
signal back.
We ended up not using these clamps that
we 3d printed to hold the cord in place,
but used what are called cord grip
bushings.
These are 3 quarter
inch cord grip bushings so we had to
dremel out the holes a little bit to
make them quite large. But now the cord
is secure in place.
Won't move around on both ends
that's kind of nice.
Um and then we have our current sensor.
Our current sensor is a just a like
ring of magnets it clamps on and
only to the hot wire.
And by using magnetic fields, it's able
to accurately determine how much current
is being is flowing through the wire at
a certain time,
So you'll see in our relay we have three
terminals here. And
we have
this one is the common and this one is
normally closed, so if there's no signal
going to the relay the switch is
normally closed which means it will
allow power to be flowing through.
Um
so i will quickly move on to the
demonstration.
I will plug the cord into the wall and
as soon as I plug it in
we'll see the Christmas tree light up
and we get some lights going.
So uh
we'll first look at the relay as I feel
like that is the most important part. We
have two LEDs. The one LED that you see
is on right now and we have another LED
on the other side. This led shows that
the relay has power.
Um the other led shows that a signal is
being uh sent to it.
That makes
it uhh
turn off
or reverses polarity.
Anyways you can see the Bluetooth. This
is the Bluetooth sensor blinking showing
that it is sending signal to our app
which i will showcase right now.
One second.
All right and here it is.
Uh is it mirrored for you guys as well
is current backwards?
Professor?
Yes.
Okay well that's a shame but I assure
you we did not make the app backwards um
so... It looks normal.
Oh it it does it? Looks normal okay, I
guess it's just mirrored for me then.
Yeah so,
so here we are the first thing you do is
tap the bluetooth symbol and then you'll
tap the one that you're connected to
already, HC-05.
Give it a second, and now we're in!
In a short while it'll start displaying
values.
These values will be small so this is in
milliamps. Just recognize that that is
less than an amp. Most current sensors
are not accurate
at small values such as under an amp,
but the temperature is pretty accurate
sitting there at 19 degrees, Celsius that
is.
About fahrenheit we're not dying over
here.
Um so now
I will demonstrate the various sensors
by using this hair dryer
so over here, we've got a hair dryer.
I'll turn it on
and we'll see the current sensor change
and we can see it go up spike up. Yeah
there we go, to about 4 amps,
spikes up to about 4 amps. Sorry for
the noise.
Um and now I'll demonstrate the
automatic shut offs. So uh Garrett
mentioned the various criteria for the
app to shut off for the relay to shut
off.
One of them was 12 amps and the other
one was 35 degrees Celsius. Now those are
very very low numbers we did this for
the demonstration purposes.
Those numbers can be changed probably
something more around 20 amps and maybe
uh above 60 degrees Celsius, but we set
them artificially low so that we could
actually attain them during the demo and
show that they work.
So right now I'm going to do the 35
degrees Celsius.
So i'm going to take this hair dryer I'm
going to point it at the thermocouple
turn it onto hot put it on low we'll see
it go up,
and there we go turns off automatically.
And you can notice the other light on
the relay is turned on.
So now the way to reset the cord is
there is a built-in reset button on the
Arduino that resets the code.
Press that,
there it goes so it uh the relay flipped.
The
hairdryer stopped receiving power and
turned off automatically
and that was kind of nice.
The next I will do is the
um well I'll do the manual override.
So we have it going
I'll point it away so that it's not
blocking my sound. Hopefully you guys can
still hear me press the manual override.
Once I press it again,
there we go.
Three light turns on, hairdryer turns off.
If I press it one more time
relay flips.