Relay tutorial for beginners (Mechanical & Solid State Relays)- Electronics Crash Course #12

hi today we'll be learning about relays both mechanical and solid-state relays now a few videos ago I talked about how transistors revolutionize electronics by their ability to switch on and off huge electrical loads without any moving parts just using a small electrical current now release can do the exact same thing they do the same job but how they do that switching on and off of a high load is different I really will isolate the input voltage that turns a relay on from the load while a transistor need to sync the input voltage that turns the transistor on through the load now this sounds a little complicated I'll explain or more in-depth as the video progresses now t types of relays exist mechanical and solid-state relays let's start the simple mechanical relay so here I have a simple 12-volt mechanical build a and we're going to tear it apart to see how it works also this order really it looks like I'm using a simple screwdriver we can pop the top off and you can see the insides so if you power down you can physically see the mechanical really moving to turn it on but that's not enough let's actually take some wire cutters cut it open and see how it works so having cut it open you can see the core of the relay it's a lettre magnet electromagnet actually activates and allows these contacts to physically move using a leaper arm since relays rely on this physical strip of metal to conduct electricity they can conduct a lot more voltage and current than your average transistor if you choose to use a high-power transistor instead I really can be a much more cost-effective solution as well however this mechanical nature also provides some downsides firstly relays are much larger in the physical footprint compared to transistors this is because again they have to house an electromagnet physical space moving contacts etc the relays are also not great for switching signals that means signals that turn the relay on and off very rapidly are not suitable for the relay because it really takes time to physically move its arm up and down unlike a transistor that can actuate incredibly fast multiple different types of relay configurations exist so firstly here we have the single pole single throw really it's a very simple really that can either be on or off that's it this is one channel of lectricity now secondly we have a single pole double throw TV this will have two states where depending on the side that the relay is flipped words one side will be conductive or the other side will be conductive thirdly here we have the double pole single throw a really now this looks a little complicated and how it works is this is linking on between the two different poles so there's only mix of two states either on or off but the advantage to this is that you can actually control two separate circuits each on their own lane now Paul refers to the number of outputs while throw refers to the number of positions or States per output although release can handle a much higher power it's imperative that we do not run more voltage or current than the relay is designed for the reason for this is firstly the mechanical gap now if we run an extremely high voltage across the load what can happen is that because of this physical gap the current can actually arc across the contacts and possibly even damaging you relay furthermore if too much power is being drawn while the relays in its contracted position what can actually happen is that the two contacts can fuse permanently turned really on so even though you try to power off the really that means flip the contact up the relay is now fused and is useless now electrical snubber circuit as you can see here can actually prevent damage to your relay by adding a simple capacitor in parallel to the load of your relay we must also be careful with relays since as they're powering off that means one segue from the conductive to a non conductive state what happens is an electromagnet inside releases a back EMF this is very similar to a DC motor freewheeling that means running it acts like a generator and will send a small current back to the device that's turning on or off the relay by adding a simple flywheel diode or a simple reverse current protection diode we can actually prevent the relay from potentially damaging input device you can watch my crash course tutorial on diodes to understand how that works so far it might seem that relays have to mean drawbacks or complications well solid-state relays which are going to talk about next actually mitigate most of the problems of a mechanical relay now how they work is that the input current from a microcontroller or controlling device will actually turn on a small light within the solid state relay now this light from the solid state relay will go to the other part of the solid state relay where there's a small light sensor a photocell and now when this photo cell detects that there's light being illuminated on it he'll in turn activate a triac now the track will switch your load on and off and in turn make your really conductive or non conductive now assault state really might sound like a transistor they both are switching on high-lows without any physical moving parts but transistors use semiconductors and furthermore transistors have to sync the input current into the load while a relay a solid state really doesn't have to do that the circuit responsible for driving the light that turns on the relay and the circuit responsible for driving the load controlling them load the light sensor are both mechanically separated there is no electrical link between the two let's look like really demo circuit over here this circuit is going to control an LED on the side and as you can see I'm using a 5 volt field in here so you can use it with a Raspberry Pi or Arduino so this is the code that we're going to use is a simple blink example for the Arduino and instead of having the LED blink we're gonna instead activate the relay and the interval of one second and as you can see here is the test code it turns on and off now to all this tutorial I've talked about multiple electronics such as diodes DC motors transistors for two selves or light dependent resistors now if you want to learn more about each of these electronic parts do check out my whole electronics crash course playlist down below where I've made tutorials on all these do note that this is a very introductory look into what relays are and how you can use them if you want a more detailed explanation of how they work you can look at the article written down below or follow the links that I've posted down in the comments now if you want to subscribe for more electronics crash course tutorials like these do feel free to do that and thanks for watching [Music]

Channel: Saral Tayal

Views: 11,722

Keywords: Relay, Electronics, DIY, circuits, transistors, arduino, raspberry pi, raspberrypi, tutorial, guide, engineering, tech, beginner, introductory, relay tutorial

Id: yMgcL1HG3mg

Length: 6min 37sec (397 seconds)

Published: Sun Mar 10 2019