Electronic Basics #13: Coils / Inductors (Part 2) || Reactance

let's bring the inductor basics to an end firstly I prepared the small LED circuit which is powered by a 230 volts to 15 volts RMS transformer the output sine wave with Peaks up to 25 volts powers the LED directly and as everybody would assume the LED dies in a blink of an eye now I connect my 1 Henry coil in series with the LED and it lights up perfectly with an RMS current flow of around 28 milliamps but that is weird because the resistance of the coil is only around 34 point 5 ohms if I would replace it with a fitting resistor of around 33 ohms by placing 3 100 ohm resistors in parallel the LED would still get destroyed so the conclusion has to be that the inductance itself creates another form of resistance and it is cold the reactants this time power does not get converted into heat like normal resistors would do but in a magnetic field which builds up and collapses watch part 1 if you didn't know that yet a negative effect of this is that power oscillates between our voltage source and load which strains for example our power grids this is also known as reactive power we can also see that if I decrease the inductance by opening the ayran core much more current starts to flow rapidly which means our reactants must have decreased because Ohm's law is still active less reactance means more current let's try another experiment where we can change the frequency of our sine wave it's basically the same setup just put less voltage and a function generator we start off with a frequency of 50 Hertz and can see that the LED is still quite bright now erase the frequency up - 10 kilohertz and we noticed that the led gets dimmer so bigger frequencies means more reactants and thus less current flows which makes sense because the magnetic field still has the same build up and collapse time but the time where current can flow normally gets shorter the final formula to calculate the inductive reactance looks like this 2 pi multiplied by the frequency multiplied by the inductance since we know this is a variable resistor based on the frequency we can build noise filters or music frequency filters quite easily here I did a small simulation in ltspice to demonstrate that if we add a 5 kilo ohm resistor we can keep out frequencies under 800 Hertz with this high-pass filter or we can keep out frequencies of above 800 Hertz with this low-pass filter if we built this small circuit on a breadboard with an n-channel MOSFETs we can for example detect the high frequency signals in your favorite song it's not that useful but you can build upon that idea next I hooked up my one Henry coil with a 10 ohm resistor to my 50 volt RMS transformer if we take a look at the voltage and current form we can clearly see that they are not lined up perfectly like it would be with a simple resistor circuit this is called a phase shift and it can reach up to 90 degrees with an ideal inductive load here I can change it very easily by playing around with the iron core this means the phase shift is capable of telling you how much inductance is in your circuit or even in your power grid another example for this would be the small microwave motor which as you can see is an inductive load because it creates a phase shift of around 36 degrees at the end I want to show you an inexpensive alternative to an RLC meter which I often use to measure inductance or capacity it's this so-called transistor tester which you can get from ms or eBay for around 20 bucks as you can see the precision is quite good when I try to measure my big self-made coil but for smaller ones like this 80 point 6 micron recoil the resolution of the measuring range is just not big enough it's still good though for $20 it can also measure resistance capacity and even the gain of transistors very handy and it's based on a German project from mic controller nets so you know it's gotta be good there is link to it in the video description and if you buy one you support my channel which is awesome by the way with that being said let's end the talk about coils here I hope you liked this video don't forget to Like share and subscribe stay creative and I will see you next time

Channel: GreatScott!

Views: 445,312

Rating: 4.9602375 out of 5

Keywords: Inductor, Electrical Reactance, Electromagnetic Coil, Electronics (Field Of Study), inductive reactance, reactance power, phase shift, electronics basics, greatscott!, tutorial, how-to, explain, coils, coil, inductor, inductors, power, frequency, inductance

Id: XCnI6ZOYKes

Length: 5min 23sec (323 seconds)

Published: Sun Jun 07 2015

Reddit Comments

[u/Lordmofo]

Great video, as usual !