Welcome back!  We love having you. And we're excited to be here as always. Now today's discussion is on pulse width modulation. This is just another means of controlling heat. It's just a little different. It's another method to get at the same end result.  Principle is something you don't violate.

I've got pulse width modulators. They operate. The same principle is just a different way of getting there. I've got one here, this is the 120 volt model. I've got a light attached to it. These are really unique because they do work a little bit differently. Same result, but they work a little bit differently than a p ID. 

Since we all know that the P ID based on timing with an on off cycle has an average percentage of power output, as opposed to a pulse width modulator, which just modulates the width of a pulse. I don't want to get too technical, but it modulates the width of the pulse so that the average apparent Power is constant.

This is really simple. I've got this thing set at 30%. It is 42 volts, I've got it plugged into 120 volts. But since I'm using an SCR in here, and it's modulating the pulse of that 60 cycle, remember we talked about that I'm only providing 42 volts to it. Here on my amp meter, I'm not going to read anything because a 60 watt light bulb which I have right there, does not draw enough amperage. This does not indicate fractions of an amp. And if we use our 60 divided by 120 60 watts and the 60 watt light bulb divided by 120 equals point five. That's the amperage that a 60 watt light bulb is going to draw at 100% power. 

It's not going to register on there. Even when I go up to 100%, it'll still say zero, but trust your lying eyes. The light bulb is just barely lit, it's dim, and only because it's provided 42 volts. With that 42 volts, there is a fraction of amperage that correlates with that voltage. But as we increase it, then you'll notice here you'll notice that the light bulbs start to get brighter as I increase the power now that's 50% power, it's 7173 74 volts. 

I can go all the way up to let me go to 106 volts now 110 volts at 76%. And let me go all the way up to 100%. Just hold it, it'll scroll all the way up. That's 125 volts provided to the light at 60 watts. And that's about point five amps. We're not going to read any amps on our amp meter. That's exactly what your heating air heating element does.

Your heating element will operate either on a very low voltage or a very high voltage. That's really what's going on. So we're making it work at full power or a portion of that power throughout the cycle depending on what we select. Very similar to a p ID, which does it exactly the same way only differently. It does pulses of on off and on for an average over a period of time for a total power output. This is really rudimentary and it's great. The equal footing with any other kind of control. 

It just takes human intervention to control it. Now what do we need for this I've got, I'm gonna unplug it and turn that light off. The 240 volt model. It operates exactly the same way. And I've got that 3000 watt element in this three gallon mini still, it took about the same 17 minutes or so to go from 72 degrees to this was shot up over 200 degrees pretty quick, pretty rapid because I wasn't controlling it.

I was I just had it on at 100%. The other thing you'll notice with a pulse width modulator on 240 volts is the voltage doesn't change. The voltage doesn't change because you have too hot leads. Since a 3000 watt element pulls 13.5 amps at 100% on 240 volts. 3000 divided by 240 equals whatever that equals is the amount of amperage it will draw at 100%. We can adjust the amperage. I've got this one set at 13% right now. And the reason it is at 13% is because that's where I set it after it's shot up over 200 degrees. 

I want the temperature to come back down so I can tell you what happens and I'm at 138.8 degrees. The reason that I'm at that temperature is because unlike a p ID, this has no feedback mechanism. You have to create that yourself which is I just put a thermometer on it, I've got a digital thermometer stuck in the top. So I'm going to read that. And then I'm going to use my fingers and I'm going to manipulate my power output to try to match a certain temperature.

If I increase that, I'm gonna go to 25%. And we should notice a temperature it is 130 7.8 138 139. So you notice that the temperature starts to come up, but it's coming up rather gradually. And that's a really good way to control your temperature using a pulse width modulation. 

Let's move up to 50% Okay, 50% Power is running through by SCR and through into my element. And I'm at eight amps. And it's now 150 350 450 556. It's starting to progressively go higher quicker, the reason for that is my element is running it half power, half amperage. If we turn it on, it's 177.  The benefit is, you've got total control over your system just like you would any other controller. It's not a con that you have to play with it back and forth.You'll find your own sweet spot. And I messed with this earlier, and I played with it for about 30 minutes. It took me about 30 minutes. And what I determined was that right around 35 to 38% power, I was able to maintain somewhere around 174 degrees.