this video is sponsored by elektor who not only published the electromagazine which comes with awesome articles about everything related to electronics but they also recently launched a new lcr meter which will help me later during the video and save me a lot of time while experimenting so feel free to have a look at it on their website and while you're at it you might be interested in checking out their project archives with over NUMBER_TOKEN NUMBER_TOKEN diy electronics projects all you need is a membership which you can get quite a bit cheaper by clicking the link in the video description first off you might be asking yourself why i'm making such a big deal of coil measurements i mean if you want to design such an awesomely efficient switch mode power supply then all you would have to do is to follow the given formulas to calculate the required inductance get yourself a fitting inductor with this value solder it in place and it just works and yes because the power supply uses a rather low switching frequency of only NUMBER_TOKEN kilohertz the inductor still behaves just like an inductor for shadowing but if we look at other power supplies we can easily determine that they're utilizing way higher frequencies in this example around NUMBER_TOKEN megahertz which the inductor apparently does not mind though because it's still doing its job just fine right to find that out i disordered it from its pcb and hooked it up to my function generator and oscilloscope in combination with a shunt resistor to measure not only the voltage across it but also the current flowing through it and by adjusting the frequency to the previously utilized NUMBER_TOKEN kilohertz we can see that the current waveform is lagging with a phase angle of around NUMBER_TOKEN degrees in comparison to the voltage which is a completely normal behavior for inductors but if you're super confused right now then i would encourage you to watch my video about impedance to truly understand what is going on here because now i'm slowly cranking up the frequency to the higher NUMBER_TOKEN megahertz and as you can see on the oscilloscope our phase angle decreased just a tiny bit the reason is that there exists no ideal inductor which only comes with inductance every inductor also comes with a parasitic resistance which is partly the resistance of the wire and also a parasitic strike capacitance which represents mostly the capacitance between the coil windings this value is of course super tiny but it is still there which means there exists a frequency at which the inductive reactance equals the capacitance reactance this frequency is the so-called set resonant frequency and above it the inductor will actually start acting more like a capacitor than an inductor while below this frequency the inductive characteristic overweights but don't worry commercial power inductors usually have a high self-resonance frequency which in the case of the coil we had a look at so far seems to be around NUMBER_TOKEN megahertz and it was actually kind of funny seeing the face angle suddenly jumping around near this frequency but getting back to the point because if you start winding coils by yourself for whatever reason then you can quickly create a coil that reaches the self resonance faster and thus it becomes pretty much useless which could have been avoided by properly measuring the inductor characteristics for its different application frequencies and needless to say by gathering all these values we can easily convert them into the coil quality that i'm
START_SPONSOR_TOKEN this video is sponsored by elektor who not only published the electromagazine which comes with awesome articles about everything related to electronics but they also recently launched a new lcr meter which will help me later during the video and save me a lot of time while experimenting so feel free to have a look at it on their website and while you're at it you might be interested in checking out their project archives with over NUMBER_TOKEN NUMBER_TOKEN diy electronics projects all you need is a membership which you can get quite a bit cheaper by clicking the link in the video description END_SPONSOR_TOKEN