Name: 廣播的樂趣--60個符號 (The Joy of Radio - Sixty Symbols)
Uploaded: 2021-01-14T10:29:56.000Z
Duration: 11 min 8 s
Description: 【看影片學英語】數萬部 YouTube 影片，搭配英漢字典即點即查，輕鬆掌握單字發音與用法，長久累積看電影不必再看字幕。

情態副詞

And there's a reference that would be lost on most of the audience.

This is doing his amplifier and stuff for the station.

Down the beach, boys last Norman's Colin.

Tiny wire on a penny on our penny is acting as a dialogue rectifying the signal.

And we're picking up a station called Absolute radio all the way from London on a piece of wire hung out of my office, which is acting as an antenna.

And actually, if we didn't have this on, we had a pair of headphones.

This thing would work with no power source.

What are you doing messing around with this?

So it all goes back about how many years would be 41 years?

This book was actually published in 1972 on DDE.

My Uncle Benny was a radio amateur, really interested in short wave radio and listening to short wave radio building.

See, and I, when I was about 10 use this book to build something which is called a crystal radio.

So we've got a coil, which is an induct her.

We've got a capacitor, which we consume so we can change the capacitance, a dialogue, which is something called a Rectifier, which means that only lets current flow one way on the pair of headphones.

Or indeed, I used a new piece exactly like this.

That's what's called Appear to electric over Crystal ear piece.

Is this the actual book or this is This is I really wish I had the actual book.

I suspect if I had the actual book, it wouldn't quite be in this good a quality.

There's a whole new series of Ladybird books, by the way, that some of you might have seen pretty good the zombie apocalypse, mindfulness and best of all, the student Lisa finds a revision timetable very tiring.

That is because it starts at 1 a.m. When she could be sure.

Dear time television has definitely finished there.

A spoof of these books, You know that I learned a lot.

There was this one on this one on a whole host of other ones.

Basically, you used a plank of wood, and we weren't even as technical as putting screws in it.

What use instead what I would call thumbtacks or drawing pins on.

We just press those into the board and we wedge their component leads underneath.

So here, right, we have our Coyle Coyle here capacitor, which is this thing.

I went down to our ever friendly electronics workshop and said I'd like an old style vain capacity because I want to recreate this on.

Then I hunted through a few of these to find one with the good capacitance on one that was actually working what they used to do.

And for example, days were also known the court known as crystal radios, but there were also known as Fox Hole radios on prisoners of war used to build them in the in the Second World War on day couldn't get their hands on something like this.

Instead of changing the capacitance and having a capacitance variable, you can choose the inductive.

It's on the way you do that is you have different water called taps on the coil.

So instead of connecting the dialled right at the end, he might connected here or here or here or here, and that allows you to change the frequency that you're detecting.

So when I initially built this all those years ago, we used something which is called a silicon dialled important thing with this is it only allows current to flow one way, and so instead of it's sloshing back and forth like this, it's just a loan it to flow in one direction.

That's really, really important in terms of being able to detect the signal on to pull out the signal to extract the signal, the music, the sound, the voice from what's called the carrier wave, which is the radio wave itself.

The radio wave itself is a combination of what's called a carrier wave, which is very high frequency, maybe a 1,000,000 times going back and forth, maybe a 1,000,000 times a second electric field flipping back and forth megahertz.

And of course, the audio signal is much, much lower than that.

And so this, along with the other elements in the circuit, pulls out the audio, the music they talk, whatever from from the overall radio with Phil, when you're a boy, you said that you used used one of them.

So what I've done today, this is amazing.

So with a penny in the UK, at least it's different in the U.

Don't may wicky homework on this in the U.

But of course that copper oxidizes and this is a fairly badly oxidize.

You can see even little patches of green stuff on this penny.

If you look carefully on, the wonderful thing is just like silicon.

Copper oxide is something called a semiconductor.

And so with this type of dialled, what happens is you get two different types of silicon, one which is doped, what's called an type on another, which is called pay type.

The doping changes the conductivity, and you sandwich those together on the when those two materials interact on mixed to a certain extent.

What happens is that you get a barrier for electrons to flow in one direction on DDE, not a barrier in the other direction.

Now, wonderfully, you can also do the same thing with a metal on semiconductor contact, and it's called a shot key.

This is about the most rudimentary form of a shock.

One can imagine it's called a cat's whisker and that we've got a wire trotting very, very gently because we want to touch the oxide.

We don't want to dig through to hit the copper or the steel underneath because then one short over the night.

So we got this thing, this wire, and it's acting almost like a spring.

This might involve quite a lot of swearing.

Can you imagine being in the sort of trenches in your prison award?

Just moving this thing around are so frustrated you won't have some sort of outside contact.

What's happening when you hit the tables?

So this contact here is moving, ever, ever, ever so slightly.

So it finds a nice spot on the penny where we got a good come on, you take Okay, so that's not great.

So it depends very much on where you are on the penny consumed it a little, but nobody.

When I first did this, I think I got more excited than when I did.

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廣播的樂趣--60個符號 (The Joy of Radio - Sixty Symbols)

flip

expect

strain

barrier