Hi, aren't you excited about the new episode of electro boom 101? I haven't made one of these in ages, which is great. You have already forgotten all the previous ones and have to re-watch more watch time and revenue for me here. I want to talk about what a power supply is and then show you a bunch of electronic life hacks. So what is a power supply? Well, i think the term is mainly used in electronics, where a device provides power to your circuits to turn them on kind of, like your mom ow, you need a full tummy to work, but mom an apple a day keeps the doctor not with your mouth full With the mom's care, your energy level and adrenaline is never low power supplies, though this well.

This is what we call an electronic danger noodle or, as we call it in persian, el ektarani danger. Noodle, don't make fun of my accent, you little sh and that's called a wire wires are typically made of two or more conductors to carry electricity around when they are connected to a power supply. In any case, even this is not a power supply. It's just the end of some wires going through breakers through more wires through a bunch of transformers all the way back to an electric power generator.

But even those are not sources of power. They merely convert sources of power. That themselves are convergence of solar power, which is nuclear power to start with, or from nuclear power directly all started from big bang, so the real source of power is these. Are power supplies i put a link on them in the description, but basically any sort of circuit or battery that provides electric energy to the downstream circuits.

To turn them on is a power supply they can be in series or in parallel, to provide different levels to different circuits in electronics. A power supply provides two things: voltage and current power being voltage times current and they can be ac or dc. A power supply tries to keep one of these two factors fixed, mainly voltage, so that the designer can easily design and analyze the circuits. For example, this electronic danger noodle outputs, 120 volt, ac, mostly fixed, but there could be fluctuations in other countries.

The level could be 220, 230, 240 or in some applications, 480 volts and so on. These are some of the symbols we use for power supplies. Make it simple. This simple form, just a circle and two terminals is used for independent power supplies, as in their output, is not dependent on external factors like heat or voltages from other sources.

This diamond shaped one is for dependent power supplies with outputs dependent on external factors like your mom. These wiggly lines shows that these are ac sources of voltage or current, but the ones with plus and minus are only for voltage and the one with the arrow is only for current. This could be ac or dc. There are other symbols out there to show voltage and current sources, but for all my purposes, i use these symbols except.

I also use this to show batteries which are a dc voltage source. Then we identified a known parameter of our source. Writing it beside it like this is a 10 volt voltage supply, or this is an ac current supply with a current equal to this, or this is a dependent voltage supply with a voltage equal to a constant times. The voltage across some resistor in the circuit.

Now we'd like to make our life easy as designers who said life is easy. Life is not easy, but we try to make it easy and digestible by making it as abstract as possible. When we understand that, then we make it complicated one step at a time like how parents feed knowledge, in small doses, to their children and nothing solidifies those information in a child's brain as much as a good old slapping. So these are ideal power supplies.

When i say it's a 10 volt supply, it means it's 10 volts, no matter what, if i put it across a 10 ohm, ideal, resistor and current flows through it. We know that the current is equal to 10 volts, divided by 10 ohms or 1 amp or similar for a current source, no matter how we change the load from zero to infinity. The voltage here remains the same, but then we can be more realistic. For example, we know the wires connecting the circuit or even the power supply itself is not perfect and has some resistance, so we can add a series resistance to the circuit to account for the wire and supply resistance.

Now it means if we connect the load. The voltage across the load won't be the same as the supply voltage, because there is some voltage drop across this resistance. Now, let's calculate the load voltage or vl, you should have all the information you need from my previous electroboom 101 episodes. But here all these components are in series, so we know that the same current runs through all of them that we call i from jbl.

We know that the sum of all voltages across all components in a loop is equal zero. We pick a direction to go inside the loop and if we enter the negative terminal of a component, we write a negative voltage for it and if we enter the positive terminal, we write positive. And so we have that the supply voltage is equal to the sum of the resistor voltages from ohm's law. We know that the voltage across rs is its resistance times current and the same for rl and the current is the same, and if we get these two and put them in our kvl equation, we get that the supply voltage is equal to i times the sum Of the two resistances, the first interesting electronic life hack, see vs divided by i, that is the equivalent resistance of these components, is equal to the sum of them for series components.

Was this a life hack or just basic electronic knowledge? What is a life hack? Really this means you can replace all the series resistors or impedances for that matter, with a single resistor or impedance, with a value equal to the sum of all those series components. Remember this: okay back to our calculation, so we had source voltage is equal to the current times the sum of the resistors, and we already knew that the load voltage was current times rl or i is equal to v over r. So from these two we get this and we move things around a bit and we have. The load.

Voltage is equal to the supply voltage times, rl divided by rl, plus rs dingingly needing another life hack. These life hacks are, but this circuit is called a resistor divider, where you can get a different output voltage by dividing an input voltage with two resistors based on this equation. Remember this! So you see when you have a non-ideal power supply with internal resistance, and you connect a load to it. Its output voltage drops, which is the case for a lot of real power supplies like a battery, see, for example, the voltage across this battery is 1.33 volts.

But if i connect a 1 ohm resistor across it, its voltage drops to 1.28 or, for example. This is a 1 volt supply with a one kilo, ohm resistance series to the output, and if i connect another one kilo ohm resistance from the output to ground, you see the output voltage drops to half a volt for a current supply. Its current never changes, ac, rms or dc, no matter what load you put across it, just that the voltage across the load changes by the load. Of course.

In reality, you can't have an open circuit current source, because it would mean that it is shoving current into an infinite resistance which results in infinite voltage across it kind of the same as having a short circuit across an ideal voltage source which will result in infinite. Current a non-ideal current source is modeled by a parallel resistance across it. A series resistance wouldn't affect the output current, because the current, through all series components, is the same, but with a parallel resistance. If you put a load across it, the current splits between the two resistors from kcl looking at this node, the sum of all currents entering the node must be zero.

But these two currents are leaving the nodes, so they appear negative in this equation, so the supply current is equal to the sum of the two currents going into the resistors elementary. We know that the voltage across all parallel components is the same. So this current is equal to that voltage divided by rs and that current is equal to the same voltage divided by rl, and if we place these into the equation from our kcl, we realize that the source current is equal to the source voltage times. The sum of the reverse of both resistances omg is divided by v, which is reverse of the equivalent.

Resistance of this circuit is equal to the sum of reverse of rs plus reverse of rl third life hack. You can replace all the parallel resistances or impedances for that matter, with a single equivalent resistance or impedance, where the reverse of the equivalent resistance is equal to the sum of reverse of all these parallel resistances. Remember these two for two parallel resistors. We have this which, if we solve we get equivalent resistance, is equal to r1 times r2 divided by r1 plus r2.

Another thing to never forget, which also shows us that, in a parallel circuit, the equivalent resistance is always smaller than every single resistor. So back to our current source circuit, we already reached here and also we know for rl that v is equal to rl times il and if we replace v with this one, we get that which resolves into this load. Current is equal to source current times. Rs divided by rs plus rl, we have a current divider circuit, where i out is equal to i in times r1 divided by r1 plus r2, remembering our voltage, divider circuit v out was equal to v in times r2 divided by r1 plus r2 life hacks left And right here's an example: i have two one ohm resistors in parallel and i'm gon na put one volt across them, which means one amp through each resistor.

Two of them means there should be two amp through all of it connecting them. You see, we have 1.88, not quite two amps. The reason is that my wire connections are not perfect and have their own series resistance and voltage drops that reduces the current, and one last thing is that two smart guys called thevenin and norton showed that you can replace a complex circuit with ideal power supplies and Resistors like this, with simple models like this voltage supply for thevenin, or this current supply for norton ding ding ding ding. You must remember that this only works for linear circuits and all you need to do to make sure all these behave exactly the same is that their two boundary conditions must be exactly the same, which is the open circuit output and short circuit output.

Let's do an example: imagine we have a thevenin circuit and we want to convert it into a norton circuit. What we do is that we open the output, so there is no current running through this circuit and all this norton current only runs through one resistor. The open circuit voltage for this circuit is equal to the supply voltage, because no current means no voltage across the resistor, so open circuit voltage is equal to the thevenin voltage in this one. The open circuit voltage is equal to the voltage across the resistor, which is r times i just like that, and these two must be equal and when we short the output, the entire power supply voltage falls across the resistor, which means the short-circuit current is equal to This voltage divided by resistance just like this, and if we short that one all the supply current will only go through the short circuit, so the short circuit current is equal to the supply current, and these two must be equal.

So really all you need to convert this to that or that to these are these two equations and this change can make your analysis much simpler. Let's do a quick example. Imagine you have this circuit, which is pretty hard to analyze. You can simply replace this thevenin circuit with the equivalent norton circuit here and this one with the equivalent circuit here using the two equations.

I showed you earlier so now. You have three current sources and three resistors in parallel and of course, when components are all in parallel, you can move them around and it doesn't affect the circuit. So you put three current sources together and three resistors together and three current sources is equivalent to a single current source, with a current equal to the sum of all those currents. And of course i showed you how to calculate parallel resistors to get this one.

So, all of a sudden, this complicated circuit converts into that watch it that's it. These are pretty much the most important things you need to know about electronics and soon, after learning about a few more components, we can put our own circuits or possibly schematic and pcb together using my favorite software ultion. That's why i made sure that they sponsor my video really. I used a ton of different design softwares in my time before i ended up at ultim and by far that's the best software i've ever used and when they sponsor me it means i get free license.

But also you can get 30 off of your license if you use my link in the description so use it, and thanks for watching pay.