So I was wanting to find out what the value of this inductor is, but when I put it in my little tester here It doesn't like it. It just tells me that it's a resistor So we see that this tells us that it's a 20.1 ohm resistor Doesn't tell us anything about the inductance these two inductors here have stripes on them much like a resistor has so you can Get a pretty good idea of what their value is, but this one I don't know So I'm gonna have to figure out something else to do and I've come up with a little circuit and I'll show you How we're gonna test for the value of this inductor and get quite close So here's our little test circuit. Here's the inductor that I was trying to measure This right here is a 10 nanofaird a .01 microfarad same thing capacitor 1% tolerance and this is a 1k resistor This is not critical. You could have a little bit smaller a little bigger wouldn't make a lot of difference These are this is our signal coming in our test sine wave coming in and this goes out to the scope and Here's a schematic of the circuit itself. So we've got the adjustable sine wave generator here It's frequency accuracy is basically known to a hundredth of a percent The capacitor that we have in here that we're going to be using as our half of our tune circuit here is 1% So and I'm confident in that I've measured that et cetera I've had experience with it so I'm confident in that It's the unknown inductor here that I really don't know what the value of this thing is There's nothing on here no coloring no labeling of any sort so it's it's pretty much a guess And we're gonna go and use scope channel one the yellow trace here and have a look at this and here's what we can expect Here's what here's the way it's going to operate as our free as we run our frequency back and forth here The voltage that appears across this inductor is gonna go up or down depending on where it is in this tune where where we where we find ourselves and And so we're gonna be measuring the voltage across this inductor capacitor pair the inductor Capacitor pair is what we're measuring the voltage across and the frequency is Being adjusted on our sine wave generator So let's go and have a look on the scope and see how that looks for us So you can see our situation on the scope here the generator is putting out this frequency up here at right now 10.8 kilohertz And the voltage across that inductor right now is 174 millivolts As I go up here to the knob to adjust the frequency output if I go down We'll see that our I'm going in the wrong direction because our voltage here is going down. We want our voltage to go up And as we as we increase our frequency here We will see that our voltages increasing across that inductor it will eventually reach a peak and Then start going down the other side of that curve and Decreasing again. So we're gonna try and peak this value right here. So I keep cranking this up And it will eventually go past the spot depending on where What value it is and There it's taken a fairly big jump in the frequency because I turn the knob a little too quick and If we come back a bit so we're in the ballpark where's 338 163 if I keep going down in frequency 816 71 And then you just basically this is what you have to do is go back and forth a few times Oh, now we're getting really close There's so here's 8881 882 And now it's going down again. So there we are pretty close I saw 884 so I'll tune it back and see if we can get that We now see that our frequency is at 31.5 kilohertz So that that's our peak right here is 884 millivolts we're not too concerned about what this actual number is We just wanted to know what the maximum is because we could change that 1k resistor and that number would change whatever value We picked this the 1k resistor was just a convenient value So we were just simply looking for the maximum of this and what we're trying to find out is this frequency right here the 31.5 k So we'll throw that into our Formula basically and that'll tell us what size of inductor we have So here's the formula that we're going to use to find out the size of our inductor We now have all the unknowns figured out that we need to fill this formula in We found that our frequency was 31.500 hertz That's your F right here. We know our capacitor size because we chose it. That's our 10 nano ferrored right here 1% So we have all the things that we need to fill this out. So we put our 31.500 here and we put our capacitor size down here in in ferrets which is this number here. Now I've just written this out So you know you can use exponents if you want to but You know if this is a number the way you want to do it That's just fine too it all works in the long run Because as we do all this and do this on our calculator we find out that we end up with a 2.56 Millahenry inductor here. So now I know what that value is You