Name: モノスタブル555タイマー - 8ビットコンピュータクロック - パート2 (Monostable 555 timer - 8-bit computer clock - part 2)
Uploaded: 2021-01-14T10:16:27.000Z
Duration: 12 min 50 s
Description: VoiceTubeの動画で発音を聞きながら英語表現を覚えよう！学べる英語：

So in the last video, we used a 555 timer here to build this little clock circuit.

様態の副詞

So we have our pulsing clock output on pin three of the triple five timer, and we can control the speed using this potentially ometer.

But there might be times when we wantto manually control the clock.

And each time we want the clock to advance one.

Why are we want their computer to advance one clock tick?

And so you might think, Well, that's pretty easy.

We just hook a button up, And so we have.

You know, this output here of the button is is pulled to ground through this resistor normally, but then when we push the button, it connects it to R R.

And so I push the button to comes on, and so we can manually pulse the clock like that.

That works pretty pretty well, and that's almost true.

It, in fact, you might be able to use this, and you might be fine with it, depending on the button that you have.

Uh, what happens is inside that button when you push it there, two metal contacts that come together to close the circuit.

And sometimes what will happen when you push the button is those contacts will bounce on.

So it'll it'll close and then bounce and then close again there.

And so what happens is when you push that button, you actually get a couple quick pulses.

And if that's hooked up to, you know, the clock of our computer and we push that button, we could actually trigger a couple of pulses when we only meant to trigger one.

If you've got you know, some issue that you're trying to debug in the computer and you've spent a couple of minutes getting it all set up just perfectly, and you're you're right at that point where the next clock pulse is where you're gonna figure out what's wrong with it, and you push this button to get a clock pulse and you get three clock pulses and it goes right past the problem.

You're trying to find that I could be really frustrating.

So what we want to do is want to figure out a way to get rid of that.

We can do that with our friend, the Triple Five timer.

But first I hooked up the oscilloscope just to take a look at the switch here.

And so when we pushed the switch, you can see this is what we'd expect, right?

But if we try this a few times, we might see some different stuff.

So that that definitely bounced right there, eh?

You don't You don't want that, because that would, you know, that would look like 123 potentially clock pulses when you've only push the button once.

So you definitely want to get rid of that into this.

Now is a triple five circuit that is gonna help us with this, uh, with the switch bouncing problem and so well, before we get into it.

Was pushed the button and see what happens.

And then a while later, the light turns off, Um, and importantly, what happens if we push the button multiple times from the light?

Only comes on once and that's what we want and this is called a D bouncing circuit.

And there's, you know, there's a lot of other ways to build de pouncing circuits.

But, uh, you know, I'm using the Triple five time or just because I think it's a fun chip to play with, and so the time you're here that's controlling how long this stays on when you push the button is controlled by the resistor and capacitor over here.

And so, you know, you remember before we had to resistors in a capacitor that were controlling the pulsing.

Here we just have one resister in a capacitor, and we'll go into more about how it works.

But basically the time that the led stays on is just you pretty much multiply the value of the resistor.

And this is ah is a two micro fared capacitor.

But, uh, apparently, these air to Micro Fareed's, uh, but anyway, the nice thing about about this is one mega own is Ah, 10 to the sixth and Micro Fareed's are 10 to the minus six.

So the math works out really easily here so that a two micro fared capacitor.

When you multiply together, you just get to S O.

And sure enough, we push the button in the led stays on for two seconds, which I guess is further confirmation that this one m f d capacitor, is really to my Crawford's anyway.

You know, two seconds is kind of long for what we want.

So what we could do is we could put in a 20.1 micro fared capacitor instead of this to my prepared capacitor.

And if we stick that 0.1 micro fared Pastor in there, that's going to give us 0.1 seconds because we're multiplying by this one.

It's kind of hard to tell, but that's what we want when we want it toe pretty much follow what we're doing when we push the button.

But we critically are getting rid of those balances and so as long as that any balances that happened within the 1st 100 milliseconds or 1000.1 seconds we've gotten rid of and that's what we want.

Let's look again at our circuit diagram and I've got the triple five time Are here the guts of it exposed here.

But the green bits out here are our circuit.

But, um and of course, we're just looking at this.

This lower half here is you know, this is what we built in the last video.

And so we've got our resistor here, which is our 11 mega home resistor.

Then we have our capacitor, which is Ah, 0.1 micro fared capacitor And then, you know, over here I've got the button hooked up.

And if you look at how this is hooked up, the button is connected between ground and pin, too.

You can see we've got a one k pull up resistor.

Basically what that does is it insures that pin too is normally connected to five volts.

It connects it to ground and then pin to goes to zero votes.

So just like before, we've got this voltage divider network going on inside the Triple five timer.

And so we're We've got five volts up here, and then we've got 3.3 volts here at this first point.

And then we've got 1.667 volts here at the second point.

Then, of course, ground is zero volts, and that's just a voltage divider.

We've got 1/3 of our voltage, 2/3 of our voltage, and then appears our full voltage.

It's so we can see right now, you know, our output is off.

So if our output is off, then you know, that must mean you know that the Q output of this s our latches off into the inverted que output must be on.

Then that's gonna be, you know, putting current into the base of this transistor.

And so this transistor will switch on and will be discharging.

There will be, you know, we'll be pulling current through this transistor.

And so you know, in this in this state right now.

Current is flowing from our voltage source through the transistor to ground on.

If this capacitor had any charge on it, that would also be, you know, discharging to ground.

And so this capacitor doesn't have any charge on it.

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モノスタブル555タイマー - 8ビットコンピュータクロック - パート2 (Monostable 555 timer - 8-bit computer clock - part 2)

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