Build the transmitter발음듣기
Build the transmitter
Build the transmitter
[Voiceover] Now we have to build our light transmitter.
It's gonna take the electrical signal from the radio and turn it into a time-varying light signal. So, here's the circuit diagram.
We have the radio, and it has two leads coming from it. Let me show you that.
So, here's the radio and here is, once again, the mono phono plug.
It's got the one band on it.
It will just work with anything you plug it into.
So, I'll plug that into the radio.
And that goes to two leads, which will connect to the rest of our circuit.
Now, in that circuit, there's going to be a nine-volt battery, which has a positive and a negative side, and a 470-ohm resistor.
If I don't have that 470-ohm resistor, when I connect the nine-volt battery to my light-emitting diode, the light-emitting diode will burn out instantly. So, we need that resistor.
Now, the nine-volt battery snaps into this battery holder.
(chuckles) I use Velcro to hold it in place on my breadboard.
The battery holder is color-coded.
The positive terminal of the battery goes into the red lead on the battery holder.
So, this red lead is the positive terminal and it goes out and it connects to one side to one side of the light-emitting diode.
The black lead goes to the other side of the light-emitting diode.
Now, my switch is simply an alligator clip that I clip to a bent paper clip.
That's how I turned my light-emitting diode on and off.
Now, there's a little bit of a trickiness about light-emitting diodes.
A light-emitting diode has two legs to it, a long leg and a short leg.
The longer leg must be connected to the positive terminal of the battery to make the light-emitting diode glow.
So, when I mounted my... light-emitting diode to my circuit, I made sure the longer leg went to the red lead on the battery.
Now, what's going on here is that electrons are actually leaving the negative terminal of the battery, going to the black wire, going to the short lead of the light-emitting diode, and they come in with the full nine volts, very high energy, and they drop their energy and turn it into light, and then the electrons with lower energy continue around, back into the battery.
It's gonna take the electrical signal from the radio and turn it into a time-varying light signal. So, here's the circuit diagram.발음듣기
Now, in that circuit, there's going to be a nine-volt battery, which has a positive and a negative side, and a 470-ohm resistor.발음듣기
If I don't have that 470-ohm resistor, when I connect the nine-volt battery to my light-emitting diode, the light-emitting diode will burn out instantly. So, we need that resistor.발음듣기
So, this red lead is the positive terminal and it goes out and it connects to one side to one side of the light-emitting diode.발음듣기
The longer leg must be connected to the positive terminal of the battery to make the light-emitting diode glow.발음듣기
So, when I mounted my... light-emitting diode to my circuit, I made sure the longer leg went to the red lead on the battery.발음듣기
Now, what's going on here is that electrons are actually leaving the negative terminal of the battery, going to the black wire, going to the short lead of the light-emitting diode, and they come in with the full nine volts, very high energy, and they drop their energy and turn it into light, and then the electrons with lower energy continue around, back into the battery.발음듣기
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