We run the chapter four, we're going to be talking about power and decibels, AC power and basic components Power and decibels. You recall Ohms law from your technician training E which voltage equals current times resistance. Current can be related to voltage divided by resistance, and resistance can be voltage over current. So there's a refresher. I know you remember all your Ohms law training from your technician class. So E is voltage is current ours resistance similar relationship
between power. Power is equal to voltage times current. Voltage can be expressed as power divided by current, and current can be expressed as power over energy or over voltage. So substituting the omes law equivalents for voltage and current allows power to be calculated using resistance. So power is equal to the current squared times of resistance, or powers equal to the voltage squared divided by the resistance. Find out how many watts of electrical power are used in
four hundred volts dc. DC is supplied to an eight hundred owned resistor, you would say, hmm. Power is equal to the voltage square divided by resistance. In this case four hundred square divided by eight hundred homes six hundred and sixty thousand divided by eight hundred or two hundred watts. So if I had a four hundred volt signal with an eight hundred owned resistor, if that resistor is going
to dissipate two hundred wats of power. To find out how many watts of electrical power are used by a twelve volt DC light bulb that draws point two amps, you would use. Power is equal to voltage times current, in this case twelve volts times point two amps two point four watts. Find out how many watts are being dissipated when a current of seven million amps flows through a well one point two K two five ko resistor. Remember,
power is equal to the current square times resistance. Were given current which is point zero zero seven amps or seven million amps times twelve hundred and fifty oms, you'd get sixty one point two five milliwatts. And so just remember if you're given something in seven million amps, you'd sometimes you want to convert it to amps, so it's point zero seven amps. To do your calculations, make sure you're using like units when you do your conversions. Okay,
calculating the power or or voltage ratio from dB. Power ratio is defined as ten to the minus one log of the dB over ten. So voltage is dB divided by twenty the log of dB divided by twenty. So inverse log notes you refer to this. I remember from your school anti log and log what it can be referred to. Power ratio of nine dB is ten to the minus one of nine over ten, and log of minus one of zero point nine is equal to eight. So this is probably the most complex math you'll need
for this course. So don't worry if you're if you're going crazy about Oh my gosh, it's not gonna be too bad. So a voltage ratio of thirty two dB, remember it's thirty two divided by twenty log, So thirty two divided by twenty is one point six. Log minus one of one point six is forty. So some useful things if you double the power or cut it in half. There's a three dB change that's a useful thing to
understand when you're talking about deep about dB. So a three dB change is either twice the power or half the power, depending on if it's positive or or or negative. And so let's say ten a dB is equal to the ten log of ten two over one. So ten log of two is equal to ten times point three three dB. This is where that comes from. So you had a ratio change of two to one. I mean I've doubled the power, and uh so if you double the power, you're gonna get three dB difference. So let's
take a look at these. So if you're looking percentage power is equal to dB over ten, percentage power change dB over ten or percent voltage change of dB over twenty. That's the way you can convert from dB to percentage. I suppose you're using an antenna feed line that has a loss of one dB. You can calculate the amount of transmitting power that's actually reaching your antenna and how much is lost in the feed line. This is how
you use so let's talk about it. So I've got a percent power, I've got one hundred percent times of log of I've got one dB loss. So you can express it as a minus one divided by t, so i'd be ten one hundred percent times of log minus one of minus one divided by ten is minus point
one seventy nine point four percent. So if I've got one hundred watts of power, and I've got one dB loss of my coats of my end of my through my transmission line, then I'm only going to get seventy nine point four watts out to the end to the antenna, So I've lost that power is all dissipated as heat in the feed in in the feed line. That's why it's really important when you're figuring out what coacts to choose or what to use. The transmission losses can be
fairly high, especially at high at higher frequencies. So uh, twenty nine point six percent is lost in the feed line, so one hundred wats out, so one dB loss in your coaxs, you're losing twenty percent of your power. So current is the flow of electrons measure in amps. You remember that from your tech from your technician class. It's measured with an am meter. Voltage E is the force that it takes to make electrons move. It's measured in volts with a volt meter. Plarity of the voltage refers
to the direction from positive or negative power. P is a product of voltage in current, It's measured in watts, So current's measured in amps, voltage in volts. Power in watts. Okay, so we're going to review our own's law. Here, Resistance is equal to voltage divided by current, current is equal to voltage divided by resistance, and voltage is equal to current time resistance. The voltage caused by a current flowing through a resistor is called voltage drop. Un let's review
our frequency. A complete sequence of alternating current is when it starts at zero, reaches the peak, comes back through zero, has a negative, and comes back to the zero itself. That whole loop is a complete cycle. The number of cycles per second is a current frequency, and it's measured in hurts. And a harmonic is a frequency of of some integer multiple of the lowest fundamental frequency. A harmonic of twice the frequency is called the second harmonic, and
three times called the third harmonic. So if you had a one megahurtz signal, second harmonic would be two megaherts, third harmonic would be three megahertz, and so on, and there's no such thing as the first harmonic. The first harmonic is the fundamental itself, would be one megahertz. The speed of light is three million meters per second three times ten to the eight, somewhat slower in wires and
cables when it flows to a medium. The wavelength of radio is a distance it travels very one complete cycle, So wavelength is equal to the speed of light over the frequency. Frequency is the speed of light over the wavelength. Radio wave can be referred to by frequency or wavelength because of the speed of light constant, so sometimes you'll hear it talk about one megahertz or so many meters. We're going to talk about parallel and series and parallel circuits.
A circuit is any complete path through which current can flow. It's called the circuit. A series circuit where you have two or more components are connected so that the same current flows through all the components. That's a series circuit. The same current flows a parallel circuit. The same voltage is across all the applied components, So series circuit current flows through all of the pieces. Parallel circuit voltage is the same. The current is split between the different components,
but the voltage is the same. So remember our dB formulas. DB's equal the ten log of the power ratio or twenty log the voltage ratio. Comparing a measured power or voltage to a reference value. DB's equal to ten log of the power over the power reference or twenty log the voltage measured over the voltage reference. Positive DV values mean that the ratio is greater than one, or it's called gain. Negative dB values ratio of less than one
is called loss or attenuation. So you'll hear we talked that we use dbs a lot in amateur radio, and you'll say plus's and verminus dB. That talks about either gain or loss. Okay, what dB change represents a factor of two increase or or or decrease in power. So remember we talked about a factor of two. When you double something, it's three dB, right, because remember that's a power. Ratio of two divided by one is two, and the log of two is actually three point is point three
times ten. That's where you get the three dB, So factor of two. So we use factor of two a lot in amateurad and we talk about we've doubled the power. The power is divided by half. Well, that's a three dB change. So how many watts of electrical power is used for four hundred volts DC is applied to a four hundred zero load. We'll remember our own's law formula of If you're looking at power. It's power squared, which
is four hundred square divided by eight hundred. So sixteen hundred divided by sixteen thousand divided by eight hundred homes would be two hundred watts. How many watts of electrical power used by a twelve volt light bulb that draws point two amps? Okay? So which formul we're going to use here? So we're trying to find power, and we know power is equal to voltage times current, so twelve times point two is going to give us two point four watts. All right, So you've got to remember your
own law equation the relationships between power, voltage and current. Okay, So how many watts are asking for power are consumed when a current of seven milliampers flows through a twelve twelve hundred and fifty oh resistor? All right, So we're given a current in million amps, so we probably need to convert that to amps, So seven million amps is
point zero zero seven amps. Remember power is equal to the current square times resistance, So if I square point seven and I multiply that times twelve hundred and fifty ohms, you're going to get about sixty one milliwatts, all right, So when you see this question on the test, it seems like it's a lot of complicated math. But it's zero point oh seven square times twelve fifty and it's gonna be in milli watts. I've got million ams and ohms, I'm gonna have a milli watt answer. So remember they
give you sixty one million watts and sixty one watts. Well, it's not gonna be sixty one watts, so the answer is sixty one milli watts. Okay, what percentage of power loss is equivalent to a loss of one dB? Okay, so if you if you remember, it's twenty log of one dB, so this is gonna be about twenty uh twenty percent. So one dB loss is uh, about eighty percent of your of your power is gonna make it through,
and twenty is gonna be lost. Remember three dB is half, so one DB's about a third of that, so twenty point six percent. Remember the power equation is equal to the voltage square divided by resistance for DC. However, what is the value of E for AC power? So for AC power, it's not peak, it's not average. It's called root means square r or RMS. So we're talking about AC. Now. We were talking about direct current a minute ago, batteries and resistors. Now we're talking about a C alternating current
alternating power. If our if RMS voltage is used in the equations shown for calculating power, the result of the AC signal is the same as for an unvarying DC voltage. Okay, So the RMS for a sine wave is point seven zero seven times the sine waves peak voltage. And this picture here shows on a sine wave there's r MS, there's peak to peak, and there's peak and uh, those are related. They're they're they're related, and they're shown here
on this chart. Uh what they're talking about, and it's it has to do with the with the with the percent of the power inside the at the wave form. Point seven h seven is the RMS or the average power of that signal. And all right, some of the eight form formulas that we use for voltage is voltage RMS is a point seven oh seven times the voltage peak peak to peak divided by two. The voltage peak is one point four times voltage RMS. Volts peak to peak is two point eight two eight volts times RMS.
So these relationships, these formulas here are important to understand. Just something you're gonna have to sort of memorize and take a look at. Assign wave with the peak voltage of seventeen volts, for example, has an RMS voltage of twelve point five twelve twelve volts. You're gonna take the peak voltage seventeen multiply times point seven oh seven, it's
twelve volts. RMS as sign wave with the peak voltage of one hundred volts would be a Remember it's a peak to peak voltage, so you go peak the peak divided by two, it's fifty volts peak times point seven oh seven, it's thirty thirty five point four volts RMS. Assign wave an RMS voltage of twelve or twenty volts has what peak the peak voltage value, So this one hundred and twenty volts is what's in your household ac here.
So if you put it in the silloscope in the outlet, checked it out, it would be three hundred and thirty nine volts peak to peak. It's a pretty good sized signal, but it's one hundred and twenty volts RMS. All right, here's some definitions of measurement of peak envelope power. PEP stands for peak envelope power. It's the average power of one complete RF cycle at the peak of the signal's envelope, a convenient way of measuring the max power of amplitude
modulated signals. However, this definition is confusing, and let's talk about it a little bit. PEP or peak envelope power, is the average power of one complete RF cycle at the peak of the signals envelope. PEP is used because it's a convenient way to measure or specify the maximum power of amplitude modulated signals. And here's an example of peak of what the peak envelope power is. To calculate average AC power, you need to know the load impedance
and the RMS voltage measure. The r measure measure the RF voltage at the very peak of the modulated signals envelope. This is the peak envelope voltage has shown in the figure. Once the RF cycle is is identified, we calculate the average power over its complete duration. That's the red area
in this figure. Note that we calculate the power in both the positive and negative half cycles, and the negative they don't cancel out because they're shown in this In this example, Uh, the peak envelope voltage is squared, making both of them positive. So uh, start by measuring the amplitude of the peak, usually in volts, that is the peak envelope the pev in the figure on the previous slide. Then applied the following formula. So you notice here you're
looking for where's the peaks on this little slide right here, right? So, uh, this one is higher than these, So that's there. There's the peak on the pop positive, there's a peak on the negative. So those are the pulses you wanna you wanna figure out. So so when when when you're trying to say, what's my transmitted output power, it's gonna be
when you're at the peaks. These smaller peaks take less power than the taller ones, right, So you're looking for the tallest peak envelope power, right, the peak voltage is there. Peak envelope power is equal to volt armis square divided by r. For an example, if we have fifty volts across a fifty ome load, the peak envelope power is fifty times zero point seven oh seven. To get the RMS value divided by the load gets twenty five watts.
If a fifty load is dissipating twelve hundred watts pep, the RMS voltage is square root of the peak envelope power, which is twelve hundred times of resistance fifty homes two hundred and forty five volts. So these are these little formulas, these relationships. Is probably the most math you're gonna have to know for this general class license. It's not too bad.
You just got to understand a few of them. If in a silloscope measures two hundredvolts peak to peak across a fifty home load, what would be the peak envelope power? All right, So we've got to take we've got peak to peak, right, So peak to peak RMS is point seven oh seven times the peak to peak divided by two, all right, that's where you get the RMS value. And then you're gonna divide that by the fifty on loads.
So point seven seven times two hundred squared one hundred watts for the same device that five hundred volts peak to peak, the peak envelope power would be six hundred and twenty five watts. Okay, So one hundred wats six hundred and twenty five watts, So PP equals the average power if an amplitude modulated signal is not modulated. Okay. An example this one is when modulation is removed from the AM signal, leaving only the carrier, or when or
when a CW transmitter is key. An FM signal is constant power signal, so PEP is always equal to the average power of an FM signal. In other words, if an average reading WAT meter connected to your transmitter reads one thousand and sixty watts, when you close the key on CW your PW, your PEP output power will be one thousand and sixty watts. Okay. So what is the PEP produced by two hundred volts the peak across a fifty O dummy load? Okay? So how would you do
this one? Well, I guess I need to put that. Should have told you. So it's going to be peak envelope power two hundred watts peak to peak. So you got to convert that to peak. So two hundred divided by two divided by fifty is one hundred zermes. What value of an AC signal produces the same power dissipation and a resistor as a DC voltage of the same value. Okay, it's gonna be the RMS value because an AC signal, remember is peak to peak. But the RMS value is
the point seven to seven. That's the equivalent of the DC power of the of the DC voltage. RMS is what you want to use. What is the peak to peak voltage of a sine wave when an RMS voltage of one hundred and twenty volts, so it's gonna be one hundred and twenty volts times one point four, which is gonna be around three hundred and thirty nine volts,
I believe, yep. So this is what Again, if you measured the AC outlet at your house within ASILL scope, you'd see three hundred and thirty nine volts peak to peak. But what we're told it's one hundred and twenty volts. That's the r MESS value. Okay. The ARMISS value is what we normally characterize for the AC voltage at your house. What's the ARMIST voltage of a signed way with the
value of seventeen volts peak? Okay, so it'll be seventeen times zero point seven, which will be around twelve volts. What's the ratio of a peak to peak average power of an unmodulated carrier. Okay, peak to peak to average, it's about points. Well, it'd be one peak to peak. Oh for the ratio of a peak to peak to average power of an unmodulated carrier is it's unmodulates. What's exactly the same. All right. Once you modulate it, then the power is going to get less point seven oh seven.
But if it's unmodulated, all the powers is at the carrier itself, so it's one. The ratio is the same. What's the arm miss volt? Did you across a fifty zero load dissipating twelve hundred watts? Okay, so we're gonna say equals I R fifty divided by that's gonna be about twelve hundred uh divided by fifty that square met to that, it's gonna be about two hundred and fifty
volts two hundred and forty five volts. What is the peak envelope power of an unmodulated care If the average power is one thousand and sixty watts, it's it's unmodulated, so it's gonna be one thousand and sixty watts. What's the peak envelope power of five hundred volts peak to peak across a fifty load about sixty peak to peak cross about six hundred, yeah, six hundred watts. Now we're gonna talk about some basic components. We're done with the
math for a while. Three most basic components resistors. They're designated to have an R. They're used to resist the flow of electricity, and they're measured in omes. So resistance are omes. Capacitors usually shown designated with the letter C. They store electrical energy and they're measured in fare ads. Then inductors designated with L store magnetic energy measured in Henri's.
So capacitors store electrical energy, inductor store magnetic energy, so omes fare ads and Henri's R, C and L. Typical values associated with components include the nominal value, the tolerance,
temperature coefficient, and power rating. So if you go by a capacitor with a certain value like say one hundred microfarads or a hundred peokle fareds, it'll come with the tolerance nominal values one hundred peokle ferreeds, but has a tolerance plus or minus a certain amount temperature co efficient, How, what's the tolerance versus what's the capacity's over temperature and a power rating. Capacitors are volts, so those are typically
the characteristics that describe the component that you're buying. Some schematic symbols. As you recall from the technician class, a schematic is as a paper drawing of electrical components connected together. And resistors have looked like the little squiggly line here, and there's different symbols for different types of resistors. These are the common ones. There's a fixed resistor, variable photo resistor,
adjustable tact resistor, a theoristor. Capacitors show up on schematics look like this, and there's different kinds of capacitors, fixed and non polarized and polarized which we call electrolytic variable capacitors feed through. So this is how they be represented on electrical schematic. Remember, electrical schematic is how you hook interconnect these components together to form a circuit. An inductor symbol usually looks like this. Uh, there's air core, iron core. Uh,
there's actually transformers. A variant of these fair eyed beads is an example of an inductor. So these are what the symbols look like. There's different kinds of tubes with different kinds of uh uh interface, different kinds of oh connections. There's they're they're they're like diodes. There's a triode, a pentode, and a cathod. It's how many uh uh this anodes and cathods do they have? And they come in different varieties, different sizes, different types for different functions and uh These
are the symbols for tubes wiring. Again, when you have your electrical schematic and you've got wire shown on there, you can these are symbols for our wires connected? Are they not connected? Are there several wires that form like a data bus? Is it a ribbon cable? Multi cables? Is it a coaxial cable? These are ways to show common wiring symbols on the schematic. There are several common types of resistors that you can buy, and there's carbon film,
metal film, wire around, adjustable thick film. And the resistors you buy are for different applications. You may have something that needs to be non magnetic or has less of an inductance, or you need something that's going to be a lot of power, like a load resistor. Resistors come a variable resistor like a potentiometer, so they come in different type shapes for different sizes and different power ratings, different tolerances. They come in nominal value sizes, usually between
one ome and a meg ome. UH there's UH resistors I said come in different values like UH a hundred owned resistor, three hundred and thirty owned resistor. There's not a one hundred and forty three owned resistor that's made. UH. There're standard UH resistance values. So you if you're picking a resistor, you've got to pick the resistance that you need and then find the one that's closest to the value that you are trying to use. UH. Most common
units they're omes killiomes and megomes. Usually for resistors, you don't usually see a tear uh terra own resistor or something like that. So UH ohmes are uh omes killiomes and megos are the standard sizes. The precision of resistors one percent up to ten percent, depending on the application that you have, UH how well you need to control the resistance. Sometimes the resistance needs to be controlled. Sometimes it really doesn't matter too much, depends on what you're doing.
So if you've got a if you've got a a one killiome resistor, you divide by a thousand UH to get If you to get to convert from homes to killing homes, you divide by a thousand. Convert to megomes, you're gonna divide by a million. So sometimes you you've got to convert between the units. Sometimes you've got a mix of uh megomes and killiomes in the same circuit, and you want to put them into the same UH bands or conditions so you can do your multiplication in
your math easier. So this is the way you would convert between the two. Example, if I had one hundred and fifty owned resistor, it's a point one five k divided by a thousand, or one hundred and fifty own resistor divide by a million to get two point oh meg homes. So if you're trying to convert between the two, this is the way you would you would do that, and the exam here's another example of a four point seven k own resistor. It's forty seven hundred homes or
point oh four seven meg homes. So another example of I've got a megoon resistor how many homes is that it's a bunch twenty twos. Inductors come in different types there's the air, the air core which is just a y which is a winding of wire with air in the middle. Variable core that you can tune around with the US as a pickup up off the top. There's a magnetic core. Those are the common ones, like resistors
double lines indicate a magnetic core. Veriable resistors like we use in your end, like used for and for antenna tuners. There's real small inductors you can put on circuit boards. Somebody's different shapes and sizes, different symbols for them. So member aductor stores magnetic energy. Its directionally proportional to the number of turns in the area that's enclosed in the inductor. Make an inductor longer without changing the number of turns
or diameter reduces the inductance. Increasing the ability to store magnetic energy is called permeability, which increases the inductance. The type of core and windings effects inductance are very according to the use purpose of the inductor, so depending on what you're trying to make. UH variable inductors are often used in low power receiving transmitting applications, So we use those in UH to tune the i F frequency to
UH tune across the band. You usually have a variable inductor adjusted and they're adjusted by moving the magnetic core in and out of the inductor. So usually when you're tuning a circuit building a filter module, you put an inductor in there and you and you'll it has a piece of uh coil with an inductor that you can move in and out to change the inductance. And that's how you tune that particular frequency. It's a it's a moving piece. Sometimes they're threaded. High power inductors are made
by sliding the contact along the inductor itself. This is a lot of your your antenna tuners will have a roller inductor it's called in there and and a pickoff that rolls along as the inductor turns, that moves along pick off. The different values of the inductance, like the resistors, you can convert between micro Henri's, nano Henri's, and million Henri's.
This is the typical values of those three hundred and thirty nano Henry is equal to zero point three to three micro henries and so on, So you can convert from micro henris to nano Henri's milli henries. You have to do this quite a bit when you're doing your calculations, you want to convert to one to the other so you're all the same. When you have two conductors that are close together, like this picture shows here, you have what's called induced in coupling, magnetic field from one conductor
can pass through and get to the second one. UH. It's a way to share the energy between them. This is called coupling. The buildings of inductors to share or transfer magnetic energy is called mutual inductance. And sometimes this is what you want, sometimes you don't want. This depends on what your circuit is. So inductor design UH. In a toroid design like this picture is shown here, the the winding goes around a magnetic core and all the field is is is is maintained within the within the
inductor itself. There's really not a large magnetic field outside the component itself, and this makes it handy when you're when you're doing on circuit board design. You can put a whole bunch of these wound around iron core pretty close together. There's not a lot of mutual inductance sharing. Composition of the cored varies. You can the cores themselves come and powdered fair eyes. There's different types of cores based on the range of frequency that you want to use.
Some cores are better for high frequencies and low frequency, So depending on your application, you pick the core that's right for the fregency range that you want to use. Some of the core materials are exotic or have different types, they have different mixes to them, and so when you're trying to pick out a core in ham rate that we use, maybe a family of three or four different values for our frequency bands or HF VHF U h F,
So usually find a mix. The usually have a number assigned to them for the core, and you'll go find that core and go buy that piece. And they come in different diameters and sizes based on the power and the fregency range that you're trying to use. Okay, in this schematic symbol here, which one of these represents a field effect transistor, which is something we haven't talked about yet, but we'll be getting to that here in just a minute.
But the field effect transmitter is simple number. Uh, well it's actually simple number one here. That's this symbol right here. Field effect transistor looks like this, So, and what's a zener diode. We hadn't talked about that yet, but we will. Uh. It's this symbol right here, it's a diode. This is a diode symbol. A zener usually has a line like this on it cause it's uh it's it's gonna reverse diet bias to a certain voltage. So d uh. Which symbol here represents an N P N transistor. Uh, that's
gonna be number two. You haven't talked about that. Uh. Which symbol represents a solid core transformer? Alright? Uh? Transformer looks like number six over here. And what's a tapped inductor? Remember the tapped inductor is This is an inductor and it's got a tap off of one of the windings. So it's a tapped inductor. That'd be number seven. And let's see which determines the performance of a fairiche core at different frequencies. Well, it's going to be the composition. Uh,
it's going to determine the the performance at different frequencies. Uh. What's the advantage of using a fairite core over a toroidial coil core. If to use a fairite core, the magnetic properties will be optimized for a specific range magn use magnetic it's contained in the core. Large values of inductors may be may be obtained. I guess all those look pretty good to me. It is, all right. So talking about capacitors that have two conducting surfaces, it's called
electrode and they're separated by a dielectric. Capacitance is measured in fare ads. It blocks DC current flow. And the simplest capacitors a pair of metal plates separated by air. You can increase the capacitates by increasing the surface area, or moving the surface closer together, or changing the dielectric materials.
So there's three ways you can change the capacitates. And capacitors come in all different shaped sizes based on all those factors just talked about, the large surface area for larger capacitans, moving them plates closer together, putting different materials in them. All those things make up the different types of capacitors that we have. Tantalum and electrolytic capacitors are polarized.
These are capacitors the DC voltage can only be applied in one direction without damaging the electrolyte that's inside, so very important when using an electrolytic or TANNELM capacitor that you've put it in your circuit the right playerity with the right voltage. Important to check that out. If you don't, things will usually get heat up and burn up. Capacitors
have voltage ratings. Exceeding the ratings can cause an arcing between the conducting surfaces, usually destroys the capacitors, so make sure you've got the If you've got a tanelum or electrolytic, you've put the voltage on correctly, and then make sure that the voltage ratings that you're applied for the capacitor are not exceeded. Different types of capacitors Ceramic used a lot for RF filtering and bypassing of high frequencies. Fairly
low costs probably the most common. Plastic film are used in audio circuits and lower radio frequencies. Silver miica they're highly stable, low loss used in RF circuits. Electrolytic and anilem usually use in power supply circuits because you usually want to get large capacitor values and those can accommodate that very large sized capacitor large capacitance values. Air and vacuum dielectric capacitors, those are usually good for transmitting and
RF circuits. Capacitors are used to block. They can pass AC signals while blocking D six signals. They can bypass provide a low impedance path for AC signals around high impedance circuits. Used a lot in filtering for filterings itself to smooth out voltage pulses or rectified AC to even d C voltages, So capacitors used a lot to filter, especially in power supplies. Capacitors can also be used to
absorb energy of voltage transients and spikes. UH tuning very frequency of resonance circuits are are you can by changing the capacity, you can change the resonance of a circuit and you can also ingust the impedance of certain circuits. So you'll see a lot of variable capacitors used in amplifier, in a in and antenna tuners. So talk specifically about aluminum and tanielum capacitors. They're designed to optimize their storage capabilities.
The UH voltage must be applied within the correct plarity. These are plarity sensitive capacitors. They could come in large capacitans UH values UH. The aluminum uses a metal foil for conducting surfaces and dielectric as an insulating material layer on the foil created by a wet paste or jail, So they if you took them apart, there'd be a like a gel inside of them and their little foil. But they're available in super in large capacity values tannem
similar to aluminum. That's porest materials. It's immersed in electroly like inside the capacitor itself. So what's the characteristic of an electrolytic capacitor high capacity value for given volume. So that's that's the big advantage of them low voltage cheramic capacitors. They're comparatively low cost. They're not uh yeah, low low costs. They're really they're not any of those other three. But they're just general purpose good capacitors for that, but they're cheap.
Talk a little bit about transformers. Transformers uh uh can transfer ac power between two or more inductors UH through windings, and they share a common core. The windings UH two which power is applied is the primary. The winding from which the power is supplied is called the secondary. So a transformer has a primary and a secondary winding. The
two in the frome. When voltage is applied to the primary winding, mutual inductance causes voltage to appear across the secondary, and the transformers work in both directions, either a step down or a step up transformer. So I can have a ten volts here, I want to take to two volts over here, or I can take two volts here and convert to ten up or down. Works both ways, So the transformers change power from one combination of AC voltage and current to another by using the windings with
different turns a number of turns. There's a turns ratio the transformer occurs. The transformation occurs because all windings share the same magnetic field. They're wound on the same core. That's why they work like like they do. Significant change between secondary and primary using requires a change in wire size between the windings, sometimes because the amount of current and the amount of voltage that's being transferred. Sometimes you have to change the wire size for the appropriate wire
gate size and a step up transformer. The primary carries higher current and is wound with larger diameter wigher than the secondary. The ratio of the number of turns in the primary winding, which is designated by NP, to the number of turns in the secondary, which is n s, determines how much current and voltage are changed. Since most circuits are connected with voltage, most transform equations relate primary voltage to secondary voltage, so they call it ep to es.
Here's the relationship the number of secondary windings in primary. The number of the ratio between secondary voltage and primary voltage to secondary windings and primary windings is expressed in that relationship. There So the number of the voltage on the secondary is equal to the voltage on the primary time the ratio times the ratio of the windings used a lot. So what is the voltage across a fifteen hundred turn secondary winding if one hundred and twenty volts
is applied across the primary winding. Well, we use our relationship here. We say one hundred and twenty volts times the number of secondary windings divided by the primary windings, which is three times one hundred and twenty so three hundred and sixty volts ac. So if I put in a one hundred and twenty volts AC with the transformer winding ratio of three to one, I get an increase
of three on the secondary. So this is how I can This is a step up transformer one hundred and twenty volts in three hundred and sixty volts out, So what would be the secondary the primary transfer ratio and one hundred and fifteen volts to five hundred volt range. Well, you're gonna use the same thing here, the same ratios. You plug in your numbers and get five hundred over one hundred and fifteen, which is about four point three.
So that would be the churns ratio. So if I wanted to change from one fifteen to five hundred, I would do a turns ratio of about four point three to get that. To murk, what happens if a signal is applied to the secondary winding of a four to one transformer instead of the primary. Well, a four to one transformer has four times a number of turns in the prim then the secondary, applying the signal to the
secondary will increase this voltage proportionally four times the input voltage. Okay, So what causes a voltage to appear across the secondary winding of a transformer when an AC source is connected across its primary winding? Okay, it has to do with the mutual inductance. See all right, it's not capacitans. We're not talking about that it's mutual inductance. What is the
output voltage of an input signal? What is the output vultage of an input signal is applied to the secondary winding of four to one step down transform instead of our primary winding, input voltage would be multiplied times four. Because this question is a little tricky. I got the input output four to one, and I put the I put it on the secondary side, so it's a step down transformer, but I put my voltage on the primary side, so it goes it's a step up transformer going the
opposite direction. So you have to read the question understand. Our transformer can work both ways, and it's a four to one step down transformer design, but instead you put the you put it on the secondary winding, so it's it's multiplied by four. What's the primary winding wire of a voltage step up transformer? Why is it large? Usually
larger than the secondary windings. It's to accommodate the higher current should be you change the wire side because of a current issue, so it's b What is the voltage output of a transformer with a five hundred turn primary fifteen hundred turn secondary with the one hundred and twenty volts AC applied. So this is a turns ratio of three. So it's gonna be an increase of UH. Let's see IPUT transformer five hundred tern primary UH three hundred and sixty.
It's it's a three to one times times three. Al Right, Now we're gonna talk about circuits and primary UH, series and parallel circuits. So in a series circuit, UH, the current flows through all the all the components is the same, all right. In a parallel circuit, the voltage across all the components is the same. The current may vary, and the voltage on a series circuit varies between component. In a series circuit, the current is the same in all components,
and voltage are summed. It's called Kirkoff's law. Voltages add in a series circuit. In parallel circuits, voltage across all components is the same, and the sum of the currents into and out of the circuit junctions must be equal. Kirkiff's current law. Currents add in a parallel circuit, So voltages add in a series circuit, currents add in a parallel circuit. Components connected in series or parallel can be replaced with a single equivalent component. So resistors so resistors.
And if you have a bunch of resistors in series, you add the values. If you have a bunch of inductors in series, you add the values. If you have capacitors in series, you add. You take the reciprocal of the reciprocals that you add together. So we'll talk about that near in a second. And in parallel, resistors are reciprocals of reciprocals, and inductors are reciprocals of reciprocals, and capacitors you add the values. So let's talk about this a little bit. So I have a resistor and I
add another resistor in series, I increase the resistance. If I add a resistor in parallel, I decrease, and the same foreign inductor. If I add another inductor, I increase. So if I had a one Microhenry deductor and I added a one micro Henry, i'd have two microhenrs. And if I add a capacitor in series with another capacitor, I get one over the reciprocal, so it decreases, and then the opposite if you parallel them. Here's an example talks about that. So if I have a resistor and
I add some more resistors. The total resistance of this circuit is the sum of all those. If I put them in parallel, then the resistance is equivalent to the reciprocal of the reciprocal of the resistance of the resistors. So let's say I have one ome resistors here, this would be three omes. Okay, If these are one omed resistors, this is gonna be one over three, one over three, this is gonna be about one. Oh. So in capacitors, if I put them in series, it's the reciprocal of
the reciprocals. If I have them in parallel, it's the sum of the capacitors and inductors. Like resistors, they're in a series. You add up the inductance that they're in parallel the reciprocals of them. Just something you gotta learn. And uh and remember let's talk about these, right, So three one hundred home three one hundred own resistors in series would be three hundred homes. In parallel, they'd be thirty three point three homes or one over the reciprocal.
So if they're all the same values and they're in parallel, you can divide the value by the number of components. You have three one hundred microferreed capacitors would be three thirty three point three microfered and series and three hundred microfer and parallel. Okay, so resistors and capacitors the way they behave in series and parallel combinations are the opposite, but only two components. When you have only two components,
the reciprocal calculation is greatly simplified. You can just when there's you know, so you can multiply. When you have only two components, you can multiply the two together and divide by the sum. So if I have one hundred omeen or two hundred zero resistor, you can multiply one hundred times two hundred divided by the sum. So that it's pretty pretty easy way if you just have two
components without having to do all the reciprocal things. Inductance of a twenty million of a twenty mili henrys and fifty mili henry and in inductors you just in series you add them together. In parallel, you could add them divide by the sum. So twenty times five one hundred divided by seventy fourteen point twenty nine milli hendryes. So what's the total inductance of three ten milli henry inductors in parallel. Well, one over the sums, one over the
recip it's the reciprocal of the reciprocals. And what's the total inductance of three ten milli henrys in series. You're gonna add them up thirty milli hendrys. What's the total capacititans of two five nano fareds and one seventy seven to fifty pico faired in series. Okay, so they're in series, so you're gonna take You're gonna first of all, convert them all to piko fairgs, is what I would do. So by five nano fareds tomes of thousands is five
piko fareds. So now I've got an equation looks like one over the reciprocals, one over five thousand plus one over five thousand plus one over seven fifty reciprocal of reciprocals, you get equivalent to five hundred and seventy seven piko fareds. So this is a case where you you'd want to convert all to the similar units. You could either have done all nano fares or all pickol fareds. In this case I think was easier to convert to piko farads, and then once you get them through the same units,
then you can do your reciprocal calculation. And in parallel you would add them up, but again you want to make sure you convert them all to the right unit. And we get ten gets ten seven hundred and fifty piceal fares or ten point seven five nano fads. Okay. So how does the total current relate to the circuits? To individual circuits and a circuit and of parallel resistors, So parallel resistors, the current is gonna let's see, it decreases as more parallel branches are added to the circuit.
I think that's b B. It equals the sum of the currents through each branch. That's that's the Kirkoff law, that's right. What is the total resistance of a ten and twenty and fifty er resistor connected in parallel? Okay? So you've got to add one over ten plus one over twenty plus one over fifty add those together, add them back up, and let's see. I think I've got those. Let's see, that's gonna be five point nine ms. Okay, And what is the approximate total resistance of one hundred
and two hundred OW resistor in parallel. It's gonna be h one over one over two hundred plus one over one over two hundred, which is one over point zero one five, which is about sixty six point six owns or sixty seven homes. Okay, what is the equivalent capacities of two five nano fared capacitors and one seven and
fifty po fared capacitor? Again, you wanna convert the nano fared capacitor uh to pico fareds and then UH at them together and it comes out to be uh ten points seventy five nano faired d Kay if I've got capacits of three one hundred micro fared capacitors connected in series. So if they're connected in series, it's one over the sum of the reciprocals. Uh, these are hundred micro fareds, so uh one over a hundred is point oh one,
and you're gonna have three of those. It's gonna have one over point oh three, which is about thirty three point three micro fareds. All right, what's inductance of three ten military inductors connected in parallel? Again, you've gotta do one over the reciprocal of them, So it's gonna be one over point three or about three point three milli henrys. And what is inductance of twenty milli henry inductor connected
in series with a fifty mili henry inductor. You're gonna just add them together, should get about seventy mili henrys. And the twenty microferreed capacitor connected in series with the fifty microfared capacitor, it's gonna be one over the two because it's gonna be one over twenty plus one over fifty one Over that, it's gonna be about one over point oh seven, which is about fourteen point three microfereds.
And what's the following components? Which of the following components should be added to a capacitor to increase the capacitance? So if you want to increase the capacitance of a capacitor, you want to add it in in parallel, all right, ce capacitor in parallel. Which of the following components should be added to an inductor to increase the inductance? You're going to add an inductor in series D. And that's the end of that chapter right now.