Welcome to this tutorial about full-wave rectifiers.
We've done a tutorial on half-wave rectifiers and now this is an opportunity to see why
full-wave rectifiers are even better.
Now we're not going to be going into the conceptual work here, we have another tutorial on the
concepts if you need a better understanding of that, but I do just want to show it in
action.
So you can see what it's like when you have a real setup that's really coming from the
wall, really getting transformed down, really getting rectified and really being shown on
an oscilloscope.
So with that, let's jump right into it.
As I mentioned, we have this transformer that's taking our US voltage of about 115 volts down
to about 12 volts.
Now I'm going to talk about why I did the air quotes there later but yeah, right now
it's about 12 volts that is being run into our full-wave rectifier setup.
Here are set of four diodes organized in such a way that when voltages cross the dials in
one way, the current will flow one direction and when the voltage is another way the current
flows to it and another way making it always positive.
The output, as you can see is here on the oscilloscope.
So if you remember the half-wave rectifier tutorial that we've done, they would only
come up, come down and then for the other half of the cycle, it would just be flat and
do absolutely nothing, then come up, come down flat.
But here, it's up, and then instead of going down or disappearing, because we have that
unique organization of the diodes, it comes back up and gives us another spike just like
that.
And it's a beautiful thing.
Now, there's a couple of things to pay attention to when you're dealing with a full-wave rectifier.
Unlike a half-wave rectifier, it's quite a bit more complicated.
Instead of having just one diode, you have four diodes and four different nodes, and
you have to hook those nodes together properly and give it power properly.
And if you do it wrong, it's going to cause problems, you're going to short circuit and
you're going to cause things to spark and you're going to blow fuses, and that's not
good.
So like anything with electronics, it's not a problem, just take your time.
Make sure you're doing it carefully and you'll be totally fine.
Another thing that you need to worry about with a full-wave rectifier versus a half-wave
rectifier.
So the half-wave rectifier, you are only using one diode and so you only have one diodes
forward voltage drop.
And that is typically point seven volts.
Depending on how you have it, it could be more or could be less, but we're assuming
point seven volts here.
So if you have two diodes, in this case where you have to have the voltage across two diodes
in series, you're going to lose 1.4 volts across both of them.
So you're going to lose just a little bit more in that side.
But at the same time, due to the fact that you're getting two full cycles instead of
just one, even if those peaks aren't quite as high and you're losing that power there,
it's usually much much more worth it to have a full-wave rectifier than a half-wave rectifier.
And that's why you almost never see half-wave rectifiers in the wild is because they're
just so inefficient.
So let's just run over some of the numbers here.
Now I'm going to use my multimeter and it's going to be measuring AC voltage here and
it is popping up at 13.4 volts AC and then as we look at the output that comes out through
the halfway rectifier.
So this is the voltage across the load, my average is 11.7 volts.
So again, since we lost 1.4 volts, approximately 11.7 plus 1.4 is 13.1.
So it seems like our diodes are actually a little bit more than point seven volts forward
voltage drop on these.
So that's something that you should be paying attention to.
You'll also notice on here that if you can see I'm not sure if the camera is able to
catch the detail here, but I'm not only measuring the average voltage here, but the peak to
peak and RMS.
So the peak to peak here is 18.4 volts and that's why I said 12 volts earlier is because
in reality, what you're getting is quite a bit more than those 12 volts.
But once you get through everything and you get the average, it drops down significantly.
So here we've got 18 volts peak, 18.6, we've got 11.7 volts average and then 13.1 volts
RMS.
So when you're dealing with, well, frankly, anything, but in particular, full-wave rectifiers,
you need to make sure you're measuring the correct thing.
So if you say, Hey, this is going to be only 12 volts average over it, I only need something
that's rated for 15 volts, but then you end up with 18-19 volts peak to peak over, you're
going to damage that.
So make sure you're taking into account all of those measurements when you're choosing
what devices to put in here.
So that's really it.
I just wanted a really brief hands on show of what happens when you're working with a
full-wave rectifier.
I hope that was helpful and I hope it was interesting as well.
If you liked the video, give it a like, subscribe to our channel and we'll catch you in the
next one.