You can easily add to your own project for just a couple of cents. But if you got bigger energy burst when it comes to overvoltage, than such a puny diode is not enough and instead you use such a blue, almost capacitor look a like component. This is a so called MOV aka Metal Oxide Varistor and its symbol looks like this.

The name varistor already tells us that this component comes with a variable resistance which looks like this in a voltage current graph. As you can see up to a certain voltage almost no current flows, only a small leakage current, and then its resistance goes down super quickly, lots of current can flow and the voltage gets clamped to a max value.

And you are correct; this is almost the same behavior as with the TVS diode before. In fact when we put two diodes together like this to make a bidirectional TVS, then we pretty much got the same graph. In fact when we put two diodes together like this to make a bidirectional TVS, then we pretty much got the same graph.

So yeah MOVs work in a similar way by also simply dissipating the excess energy of the overvoltage as heat. As an example; I got a MOV here with a continuous voltage of 38V DC, at 47V 1mA flows and it clamps up to a maximum of 93V.

Now in theory these values would be too high to protect my 5V blinking microcontroller. But after adding the MOV to the supply voltage pins and shocking this setup continuously for quite a while, the MOV seems to do its job just fine even with slightly higher protection values. And no; I am not faking anything here because as soon as we remove the protection and start shocking again, the microcontroller pretty much dies immediately.

So yeah MOVs are pretty awesome as well and that is why you often see them at the AC input of a power supply and there they also often add a thermal fuse in series that blows as soon as an overvoltage event takes place. And last but not least for overvoltage protection, we got these tubes here which are so called GDT or Gas Discharge Tubes.

This component is basically filled with inert gas and as soon as the voltage gets too high, the gas ionizes and thus creates a conductive arc meaning once again the energy gets dissipated as heat. I only mention it very briefly here because it was the only component that could not protect my 5V circuit and the reason is simply that it is made for higher voltages.

The other big differences between those 3 components is how much energy they can handle and how fast they respond to a surge which is super fast with the TVS. And with that being said, you should now be familiar with the basics of overvoltage protection, meaning it was finally time to crack open my 25€ surge protection that was featured in my mini photovoltaic system video.

I did this because I was simply curious how it holds up to a more industrial protection like this one right here that costs around 3 times more. Now I know, it is not as expensive as the one used in my house, but I could sadly not get my hands on that one. But either way, after cracking both devices open; the differences were quite huge.

I mean while the cheapy uses tons of smaller MOVs in combination with an LED in series that you can very hardly see; the expensive one uses one massive MOV in combination with a spring lever system that opens everything up as soon as too much current is flowing. So I think the more expensive one definitely offers more safety meaning I should probably replace my cheap option here.

And with that being said, I hope you enjoyed the show and maybe learned something new. If so don't forget to like, share, subscribe and hit the notification bell. Stay creative and I will see you next time.

WEBVTTKind: captionsLanguage: enAnd it is gone.Now such overvoltage can be really annoying. I mean it doesn't happen often that lightning strikes near you, or that some inductive  switching in your grid creates an overvoltage or that you rub your feet too long on your carpet  and thus create an electrostatic discharge.But either way while such events are rare,  they can immediately destroy your electronics which we definitely want to avoid. That is why we need protective components which are all integrated in these circuits here. And while this blue disc is an obvious sign for such a protection, there are also way more subtle  ones which you might not have seen before.So in this video let's cause some targeted  destruction with high voltage pulses to find out whether overvoltage protection components really  do their job, find out when you should use which kind and at the end hopefully answer the question  why the overvoltage/surge protection in my house is quite a bit more expensive than other similar  devices that can do around the same.Let's get started! This video is sponsored by Mouser Electronics who not only offer a free circuit protection  reference guide to all my viewers (link is in the description), but also have one of the best  electronics online stores. In fact pretty much all components shown in this video are  from their site and I have been ordering their components for years now and always experienced  a very good service. So feel free to give them a shot as well because they have all the components  you could ever need when it comes to electronics.Now first off, there is obviously the question how  to create a precise overvoltage pulse for testing?I mean yes, we can create an electrostatic  discharge arc with my generator here, but its voltage and current varies a lot  and we can not easily measure them.So my idea instead was to use this  Insulation tester here which can create a DC voltage between 125 to 1000V on its probes. This tool usually gets used by electricians to check whether the insulation aka the resistance  between conductors is high enough.And don't worry, it is pretty safe to  use because as you can see its output current is limited to around 3.6mA. In fact this tester was actually too safe for my overvoltage experiments since its voltage  broke down way too quick and thus could not damage my test circuits in any way. So yeah, back to the ESD generator I guess for which we can estimate that it  requires around 30.000V to jump a 1cm long arc.But since that was a bit too high for my taste,  I instead settled on a 5mm wide gap aka an overvoltage of 15.000V. And yes; 5 pulses or arcs of this voltage immediately destroyed my microcontroller  blink circuit here which is by the way my test circuit for this experiment. I actually created quite a few of them and don't feel sorry for them because I have plenty of  those microcontrollers lying around, they are dirt cheap and currently have no other job in my lab.So to protect them from the arcs, let's move on to the first of three protective components and as  you can hopefully see, it is a rather tiny thingy.Now these components do not have to be this small,  but this is what happens when you don't pay attention to the datasheet. They can also be bigger and they are called TVS which stands for Transient Voltage Suppressor and  their symbol is similar to that of a diode.I even used them myself before in this GPS  GSM project; but don't bother searching for a diode here because you can also get  such suppressors in such an IC package.This is a so called TVS diode array and  all it does, is packing 5 of those diodes neatly together. So if you ever saw or will see such an IC on a PCB, then there is a big possibility that  it is a transient voltage suppressor IC.But anyway; on my PCB here or more easily  in the schematic, you can see that one end of each diode connects to a data or voltage pin,  while the other side connects to GND.So simplified speaking the connection  would look something like this and when it comes to diodes, this is  the orientation in which no current can flow.Except of course a very small leakage current that  is always mentioned in the datasheet and which in combination with the parasitic capacitance of  the diode, are pretty much its only downsides.But before getting stuck here with the theory,  let's rather solder these ICs to a more or less fitting breakout board and solder one diode to the  supply pin of my test blink circuit like this.And after shocking this now protected circuit  5 times like before, it keeps on working without any problems. Even by increasing the gap and thus applying higher voltages, I was not  able to destroy or overcome this protection.So what happens is, that the diode is pretty  much non conductive at its reverse stand off voltage which is 5V. But as soon as it reaches 6V, already 1mA of current can flow which quickly  increases meaning the diode becomes conductive as the voltage goes up. This has the effect that depending on the flowing current, the maximum  voltage gets clamped to around 10 to 12V.So the excess energy of the voltage surge simply  gets converted to heat through the diode and believe it or not, when it comes to quick pulses,  this diode array can handle 100W of power, crazy.And as soon the voltage surge is over, everything  is back to normal and the diode is ready for more.So all in all a pretty neat protection  that you can easily add to your own project for just a couple of cents. But if you got bigger energy burst when it comes to overvoltage, than such a puny  diode is not enough and instead you use such a blue, almost capacitor look a like component. This is a so called MOV aka Metal Oxide Varistor and its symbol looks like this. The name varistor already tells us that this component comes with a variable resistance which  looks like this in a voltage current graph.As you can see up to a certain voltage almost  no current flows, only a small leakage current, and then its resistance goes down super quickly,  lots of current can flow and the voltage gets clamped to a max value. And you are correct; this is almost the same behavior as with the TVS diode before. In fact when we put two diodes together like this to make a bidirectional TVS,  then we pretty much got the same graph.So yeah MOVs work in a similar way by  also simply dissipating the excess energy of the overvoltage as heat. As an example; I got a MOV here with a continuous voltage of 38V DC, at 47V 1mA  flows and it clamps up to a maximum of 93V.Now in theory these values would be too high  to protect my 5V blinking microcontroller.But after adding the MOV to the supply voltage  pins and shocking this setup continuously for quite a while, the MOV seems to do its job just  fine even with slightly higher protection values.And no; I am not faking anything here because as  soon as we remove the protection and start shocking again,  the microcontroller pretty much dies immediately.So yeah MOVs are pretty awesome as well and that  is why you often see them at the AC input of a power supply and there they also often  add a thermal fuse in series that blows as soon as an overvoltage event takes place. And last but not least for overvoltage protection, we got these tubes here  which are so called GDT or Gas Discharge Tubes.This component is basically filled with inert gas  and as soon as the voltage gets too high, the gas ionizes and thus creates a conductive arc meaning  once again the energy gets dissipated as heat.I only mention it very briefly here because it  was the only component that could not protect my 5V circuit and the reason is  simply that it is made for higher voltages.The other big differences between those 3  components is how much energy they can handle and how fast they respond to a  surge which is super fast with the TVS.And with that being said, you should now  be familiar with the basics of overvoltage protection, meaning it was finally time to  crack open my 25€ surge protection that was featured in my mini photovoltaic system video. I did this because I was simply curious how it holds up to a more industrial protection like this  one right here that costs around 3 times more.Now I know, it is not as expensive as the  one used in my house, but I could sadly not get my hands on that one. But either way, after cracking both devices open; the differences were quite huge. I mean while the cheapy uses tons of smaller MOVs in combination with an LED in series that  you can very hardly see; the expensive one uses one massive MOV in combination with a  spring lever system that opens everything up as soon as too much current is flowing. So I think the more expensive one definitely offers more safety meaning  I should probably replace my cheap option here.And with that being said, I hope you enjoyed the  show and maybe learned something new.If so don't forget to like, share,  subscribe and hit the notification bell.Stay creative and I will see you next time.