Peter Wheeler: All right, so welcome back.
We spoke about some issues with breadboards and we understand that shorting out a resistor
is a problem.
We don't put it across the short buses.
We put it between one bus to another bus so we have an isolation.
We also spoke up the gap down the center of the breadboard used for example, integrated
circuits, or at least keeping this half of the board separated from that half of the
board.
Again, you will need isolation between pins of an IC.
You don't want to short items out.
I'm just going to go through a few practical tricks with breadboards and placing components
that will possibly help you out.
One thing that I have here, this is a long nose pliers, and you'll note by the shape
of this tool that the jaws of this pliers are much smaller than these fingers, and so
you'll be handling components which are fairly, as we mentioned 22 gauge, 24 gauge, and by
using one of these, you'll be able to, for one, insert the component into the breadboard
pinhole quite easily and more accurately, and two, for forming the leads, because what
I tend to find with some new students is that after a while a resistor like this has leads
that look like that.
That's because they've been scrunching them in, scrunching them out of the breadboard
and it's made a mess.
You are going to be building very professional product and it should look good as well as
work well.
If you use, for example, a pair of long nose pliers, you can end up making your component
leads like this.
Simply put the jaws of the pliers here on the body.
I'm just going to show it like this.
The jaws go back to this extent to the handle, and bend the lead down the side of the jaw.
That makes a very nice bend.
It saves you from a lot of grief because what's happening inside the breadboard is there's
a spring like that.
It's like this.
You're pushing the lead into the spring to make the contact.
These are all the springs that are held together like that throughout the breadboard.
You're inserting and de-inserting and inserting and de-inserting a number of times.
That's why they get all squiggly like this, because we tend to use a lot of the same resistor
values over and over.
The thing is, you'll be able to insert much easier using your long nose pliers, and two,
you will not end up with something like this, which what will happen, which is another problem
with troubleshooting, is you'll have inside the breadboard this not making contact with
the so-called beryllium copper springs in there that are holding the component in.
You need a mechanical contact in order to get an electrical contact.
Otherwise, you're going to have a gap and the electrons are not going to be bothering
to jump the gap.
One of the first things you should invest in, and if you are professionals, you will
always have a tool kit that will go with you for the rest of your life, is these long nose
pliers.
Another tool that you could use as well in your kit, in your tool kit, is a pair of side
cutters for cutting our jumper wires, in this case here, a red jumper wire.
You will have clip leads on the end of, let's say a banana plug lead, in order to, in this
case here, it's going to connect into a piece of equipment and we're going to take a measurement
with this, but in a pinch, this jumper has insulation on it.
It has insulation on it, so inside we have a copper wire and around the copper wire we
have a insulation, some type of, not necessarily rubber material, but some type of plastic
material.
That insulation has to be stripped back such that we have bare copper.
This is copper and this is our insulation and this needs to be stripped back.
How do you strip it back?
Don't use your teeth.
That is not preferred method.
I don't think your dental plan covers it, but what you can do in a pinch is, you take
the alligator clip and insert the wire some length, like this, squeeze the tip of the
clip, and as you can see now, I pull that insulation off and I have bare copper.
When you're using cutters, if you use too much pressure, if you don't set it correctly,
you will actually nick the wire and then it becomes weak and it will break off, which
will give you another problem as far as troubleshooting, once again an open.
This is a pretty clean way of cleaning off your jumper wires.
Not cutting them, unfortunately, still have to cut the length, but definitely getting
from the power rail here in order to get into the breadboard.
That's a good trick.
I'm just going to review with you what we have just done.
Let me just put my jumper wires in, in here.
We have a few mistakes on one board and actually no mistakes on the other board.
I'm going to show you two boards here.
I'm showing you two boards.
This board, if you can see the connectors, they've been bent to shape, and so I have
a neat installation.
What I have on this board, let's point out a few things that we've spoken of.
What I have is an 8 pin integrated circuit, called a dual inline package, D-I-P, a DIP
package.
On the DIP package I have the little detent where my fingernail is.
That means that, in this case here, pin 1 is below through pin 4, 5 through 8, and in
this case, we have it straddling the gap of the breadboard so that the top side is isolated
from the bottom side and each pin is isolated from each other because the buses run this
way.
In a similar manner, I have a capacitor, this device here, on one side of the gap, and I'm
actually going to connect it to ground.
For example, if I had a circuit that looked like, and you may have one like this, let's
say you have a batter and, in this case here ... Let's see, what have I got here?
I've got two resistors as we had in the past.
This is my ground, or negative.
Sometimes we show it like this to show a ground symbol, but what I did was, I stuck a capacitor
here as well.
Just to show that circuit, R1, R2 again, C1, and this is our voltage, plus, minus, this
is our common ground.
I'm just going to put some dots there so you know I've connected things.
Then, what I've done is I've put my capacitor from one side of a resistor to my ground.
I have the other resistor going obviously across these vertical lines so that it's not
being shorted out.
Same with this resistor, it's in separate vertical lines so it's not shorted out.
The capacitor where the two joined, also joined in all at common points.
You have one big common point here and I've taken that to ground.
I hope you can see that.
Now, here I've basically done the same thing.
I've taken two resistors and a capacitor, but here are the common mistakes.
First of all, as you will see, the integrated circuit is in the wrong position.
These four pins and these four pins are all shorted together.
This circuit will not work.
That is the first problem.
Secondly, I have ... Okay, so I did put a resistor across and I isolated it between
this vertical and this vertical, which is fine, but then when the second resistor, in
this case here, is not connected to the first resistor because I missed it.
I'm over two.
Even though I think I'm in a straight line, I'm in the wrong ... The verticals are the
only connections, not horizontals.
This resistor should be in this vertical here in order to make this connection here.
In the same fashion, with this capacitor, it's essentially missing the connection here.
It's over.
Even though it's in the same horizontal line, doesn't matter.
This is only the vertical lines that are tied together, and so this capacitor is not in
circuit as well.
Those are the fundamental ones.
A good trick is the long nose pliers to, again, grab leads.
As you can see, much easier than my big fingers.
Making sure that we understand the way the connections run on our breadboard are vertical
across these short dots, where as the power buses are horizontal.
Making sure that, in this case here, I also made another mistake.
I put my positive lead and my negative lead on the same bus.
Again, these will short out.
All you're doing is bringing a wire right across your battery and your battery will
get very hot and actually explode on you.
Not appreciated.
That is another mistake that I've made here on this particular board.
Keeping these in mind then, keeping these, so called, tricks and just the proper layout,
try and lay it out according to what you see on the schematic, will keep you out of a lot
of trouble, simplify your troubleshooting days, and allow you to focus truly on the
theory as to what the circuit's trying to do as opposed to trying to de-bug poor layout,
poor electrical layout, poor mechanical layout.
Thank you.
Let's look at this one more time.
What we have here is an integrated circuit that is across the gap in the center of the
breadboard.
There is no electrical connection between these pins since they're on individual vertical
buses, and these pins on the top are separated by the pins below by this cut in the board,
no electrical connection.
We have individual pins isolated which is very important.
Here we have a resistor, a capacitor, and another resistor tied together at a common
point.
Notice that they're using the vertical bus here as their tie in point, and then this
of course is separated from there.
This is separated from there.
In fact, all the way down to the negative bus, and a lead from this resistor is also
separated from there.
Even though they seem to be in line, they're not tied together that way.
There's no short across this resistor, nor this resistor.
This capacitor is using this particular gap on the board to keep it electrically isolated,
one side from the other.
That is a correct layout for these components.
Again, we showed these components and they're incorrect.
Why are they incorrect?
Again, look at the IC.
We've got these four pins all on the same short vertical bus, these four pins all on
the same short vertical bus.
We have this resistor tied to this point, but it's not tied to this second resistor
nor is it tied to the capacitor because even though they seem to be on the same straight
line, these buses run vertically on here.
These are vertical.
The power bus, however, runs horizontally, and in this case, I made the mistake of tying
my positive jumper into my ground return jumper, and therefore shorting the battery.
Incorrect, lots of problems.
The other one, correct, very few problems.
Now, let's go through that jumper stripping exercise again.
In a pinch, if you can see this jumper here, it has insulation all the way up to the tip.
If I stick that into the breadboard, my insulation on my jumper will prevent the electrons from
getting to the copper.
I need to get to the copper in order to then have the electrons have a path to get to the
other end of the jumper.
I forgot my side cutters today and my friend didn't bring his as well.
What I do know is I have a alligator clip lead in my tool kit, and so I take the alligator
clip.
I put it over the end of the jumper.
I squeeze the tip, pull the jumper, and as you can see now, I've stripped back the insulation.
I have bare copper, and sticking that bare copper now into the solderless breadboard
gives me a good electrical connection.