#832

[@engineereuler1762]

the capacitors' ratio is the square of that of the frequencies, so in this case, the inductor's internal capacitance is 1/25 and not 1/5 of the 10n, and that is 400pf

[@robinbrowne5419]

True. The formula is FreqResonance = 1 / (2 * pi * sqrt(L * C))

[@TheElectronicDilettante]

Super cool. As you added load the waveform started to resemble the wave form of the secondary ignition firing a spark plug in an internal combustion engine.

[@theinnovati0nlab782]

Very nice video! Thanks a lot. I am currently building a custom DC to DC boost converter and running through all the necessary calculations and measurements.

[@ivanpopovic9503]

Primary resonant capacitance in your circuit is the output capacitance of mosfet since it is in order od nFs, and self capacitance of a 330uH coil is in order od pFs. It is easy to fool yourself when in analyzing the circuit one accepts all the parts of a test circuit but DUT itself, ideal. :) Also selfresonance between the inductance and mosfet output capacitance is used in PSM inverters to obtain zero voltage switching and enhance efficiency/reduce EMI.

[@shawncalderon4950]

Nicely done!

[@gauravsingh324]

Mark. The resonant frequency depends on square root of parallel cap. So if the frequency changes by order of 5 then I would guess the cap changed by order of 25. So the parasitic cap must be about C_external/25 ?

[@engineereuler1762]

sorry, repeated your comment before reading through all comments

[@magnuswootton6181]

good for converting your boost.

[@ryanjoyce88]

great explanation of the ringing, that makes sense, but what causes the overshoot at the start of the square waves, as seen at 9:50?

[@bobdoritique7347]

Merci for this video.

[@Forensic1Man]

Mark, It would be an interesting video for all if you could now go from this small "Tank-Circuit" demonstration and next show the viewers how you can make a tank-circuit for AM radio reception. You would go from theory to a practical application of electronics that people can build. AM tank-circuits can really pull in distance AM radio signals and these antennas are like magic with no wire connections to the radio!

[@TonyBarr99]

The filter capacitors of a power supply don't have an inductor or resister to form a LC or RC low pass filter. What is the other element that allows the 100 Hz or 120 Hz rectified current to be filtered out?

[@IMSAIGuy]

Are you talking about a linear supply? The ripple? The ripple is controlled with the bulk capacitor value and then the regulator circuit which follows.

[@pyrokinetikrlz]

Great video! There is also parasitic inductance in capacitors (created mostly by large legs). It would be great to see how bad is that inductance in a small capacitor with large legs!

[@IMSAIGuy]

Here is a video for inductance in resistors: kzbin.info/www/bejne/ponNd4Zogs2op6s

[@mohammadrezamajidimosleh7917]

First, I want to thank you for your helpful demonstration of boost converter. The ringing is caused by inductance and combination of any parasitic capacitances in the circuit. That includes power MOSFET parasitic capacitances as well. In circuits with high current low voltage MOSFETs, the dominant parasitic capacitance is likely to be MOSFET itself which may have as high as 1 nF capacitance for a typical power MOSFET.

[@IMSAIGuy]

You may be right, the datasheet says 375pf. I will have to repeat the experiment some day using a relay instead of a FET

[@IMSAIGuy]

I did. the resonance went from 440khz to 1.4MHz. So yes FET has the most effect. Thanks!

[@AllElectronicsChannel]

Nice! I'm just recording a video about self resonance in capacitors. You can get a better measurement of the inductor's self resonance using your VNA or SA with tracking generator. Make a jig with the inductor in series, using S21. 😁😁

[@IMSAIGuy]

kzbin.info/www/bejne/fJPShWSqiNinos0

[@AllElectronicsChannel]

@@IMSAIGuy Nice!! For parallel resonance the coax to environment transition will degrade more the measurement than for shunt resonance, I think

[@IMSAIGuy]

of course the granddaddy of self resonance is the crystal.

[@Wayde-VA3NCA]

Are there any considerations on what resonant frequency would be preferred from a converter efficiency point of view? Ie. would tuning in a higher or lower res. freq be preferred? Or maybe just considerations of what freq might radiate emissions and cause interference?

[@IMSAIGuy]

There are many considerations and I am not the person to ask. If you go to Kiss Analog channel, he just reviewed a book on that subject.

[@Wayde-VA3NCA]

Thanks@@IMSAIGuy , I'll take a look. Thanks for your videos, I learn a lot!

[@NotMarkKnopfler]

Thanks for this! Very interesting. Does anybody know (it wasn't clear to me from watching the video) - looking at the oscillation waveform of the inductor, is the centre line 0 volts? So... in other words, does the inductor effectively produce an AC output, which (in this particular circuit) is being half-wave rectified by the in-line diode? I need to learn more about inductors and do some experiments with them. Also, many thanks for the interesting tip about the transistor - that's a great part!

[@IMSAIGuy]

No, the ringing has nothing to due with that. I did a two part series that might help you: kzbin.info/www/bejne/b5Oph4eXbat4g5Y

[@ats89117]

Part of the parasitic capacitance is associated with the drain-gate junction of the transistor while it is turned off. I think if you ground the transistor's gate and source, you may be able to measure this with an LCR. Or I could look it up on the transistor's spec sheet if I wasn't so lazy! ;-)

[@IMSAIGuy]

read the description update

[@Nar235]

Calculating the self capacitance when the ratio is 5 will give 1/4 of the added capacity not 1/5.

[@chrisharper2658]

I get 346pF for 330uH at 471KHz

[@IMSAIGuy]

that matches the FET capacitance perfectly. I just did a second video removing the FET from the setup and will post that in a few weeks.

[@chrisharper2658]

@@IMSAIGuy That would be series capacitance instead of parallel. That would be a low Z at resonance instead of high. Would it ring with a low Z?

[@SpinStar1956]

Great video but you still did NOT answer the question of where the UFO's are coming from!

[@IMSAIGuy]

They are electronic counter measures being tested on unsuspecting pilots.

[@SpinStar1956]

@@IMSAIGuy Oh, I feel much better now; I thought it surely was something else. 🧐 I can sleep much better now 🛌 Hi-Hi Thanks @IMSAI Guy 👍 73…

[@IMSAIGuy]

Maybe I want you to think that 😎

[@SpinStar1956]

@@IMSAIGuy Crap! Back to square-one… 😕