How Boost Converters Work (DC-DC Step-Up) - Electronics Intermediate 1

hello once again and welcome to simply electronics intermediate episode one today we're going to have a look at this amazing circuit which allows us to step up a lower voltage into a higher voltage with quite simple circuitry you can see here there is a nine volt power supply but on the output of the circuit I have a voltmeter which is measuring the climbing voltage of this circuit you can see at the moment I'm getting 68 volts from a nine volt power supply this could be a nine volt battery or any other type of nine volt DC power supply before we go any further I definitely need to mention because we are now using higher voltages you need to make sure that you stay safe high voltages like this can give you quite a nasty shock and it takes less than 20 milliamps to stop the human heart so make sure you stay safe and don't touch any high voltage contacts if you are planning on using any high voltage circuitry so what we are looking at here is a boost converter otherwise known as a step-up converter it is a type of switch mode power supply because it uses a type of switch in this case it's a transistor to turn a part of the circuit on and off at a really fast speed switching transistors are the main component in any type of switch mode power supply so let's go ahead and explain how this circuit is taking 9 volts and stepping it up to a much higher voltage now this circuit is actually running a lot slower than you would actually see in person because every circuit cannot process the speed of which everything happens because of lack of operating power so in this case as you can see down here for every 1 second we are only viewing 300 microseconds of time which is a very very tiny portion of a second so in real life this voltage would climb almost instantly so what I'm going to do is actually slow it down even more and I'm going to stop the circuit and restart it so we're now starting at zero volts and you can see here it climbs very slowly we're up to 20 volts and closing in on 25 volts so what's actually happening here well if you watch my previous video I definitely recommend you go and watch it because we have an inductor in the circuit here so make sure you understand inductors which will definitely help you in understanding how a boost converter works so I've actually slowed it down a lot more now because it gives us more time to see what's happening so now we're looking at 20 microseconds every second if you've watched the previous video when you pass current through an inductor it creates a magnetic field when you change the voltage passing through an inductor the inductors magnetic field will start to collapse and thus inducing current through the inductor as it creates a high voltage spike as the magnetic field collapses so this circuit is taking advantage of that very property of an inductor to step-up voltage so here we have this MOSFET transistor so just imagine this as a normal on/off switch but we can switch it on and off very very fast we can switch it on and off hundreds of thousands of times a second so I'm actually electronically controlling this switch to turn it on and off with this power supply down here basically I'm supplying power to the gate of this transistor which just turns a switch on and off every 100 microseconds when we turn the switch on current can flow from the nine volt power supply through the inductor through the switch and back to the nine volt power supply as we turn the switch on and this current flows through the inductor a magnetic field builds up in the inductor now when we turn the switch off current can no longer flow from the inductor through to the switch because the magnetic field in this inductor needs to collapse and induce current through the circuit because current can no longer flow through the switch when it's off as you can see here the current actually quickly flows through the rest of the circuit and you can just see glimpses of it as the switch here is open or off current quickly shoots through this part of the circuit we have a capacitor in parallel so any time the current shoots through this part of the circuit because the collapsing magnetic field of the inductor creates a high voltage spike it gets pushed through this diode and gets stored into the capacitor because there is a diode here this stops current flowing backwards from the capacitor through to switch one it's on and back to the power supply every time we get a voltage spike from this inductor this adds to the voltage of the capacitor and therefore steps of the voltage so the voltage we see on the top of the screen here is actually the voltage of the capacitor and you can see every time this switch is open or off we get this voltage spike from the inductor flowing through to the capacitor as you can see here now as I mentioned before this would happen very very quickly and I'm quite sure this circuit would step up to around 100 volts now just so you understand as we supply voltage to this inductor the inductors polarity on the left side is positive and on the right side is negative when this switch is off the polarity of the inductor changes instead negative is now on this side and positive is on this side which then allows the current to flow to the rest of the circuit because positive is connected to positive so just to give you an overall view of how it works let's press play from the start one more time and just watch how it steps at the voltage from nine volts and how it just keeps climbing if I could make this run fast enough it would eventually settle at about 100 volts let's press play so as you can see this happens very very fast and in fact in real life would happen much much faster you can see it just steps the voltage up and continues to step that voltage up and eventually will settle out but I can't run it fast enough to show you so there you go I hope you've actually learned something about those converters and how they work I will put a link in the description if you want to learn a little bit more about them you can also interact and play with this very circuit just follow the link in the description you need to be on Google Chrome to view it you can even view or change around the circuit to get a better understanding of its operation I will be doing a video on actually making a boost converter so make sure you're subscribed to this channel stay safe give this video a thumbs up if you enjoyed it and leave any comments below [Music]

Channel: Simply Electronics

Views: 952,881

Keywords: electronics, basics, current, electric, electron, flow, tutorial, how, to, energy, hobby, multimeter, power, circuit, volts, amps, watts, simple, simply, making, bigclive, big, clive, bigclivedotcom, diy, hack, roman, ursu, transistor, Boost Converters, how does a boost converter work, what is a boost converter, basic boost converter, step up voltage, increase voltage, electrical engineering, digital electronics, ohm's law, semiconductor

Id: vmNpsofY4-U

Length: 6min 43sec (403 seconds)

Published: Sat Sep 10 2016