Decoupling Capacitors 2/3 - Calculating a minimum value and testing the effects

#75 #electronics #capacitors
In this video I look at what is the influence of the value of the decoupling capacitor. In particular, how should you chose an appropriate value, that is as small as possible without compromising circuit functionality. I of course look at the basics in the LTspice circuit simulator and then try things out on a real life circuit.
More on decoupling capacitors:
Part 3 - Resonance and anti-resonance • Decoupling capacitors ...
Part 2 - Calculating a minimum value • Decoupling Capacitors ...
Part 1 - Local energy storage • Decoupling capacitors ...
More on Series RLC circuits: en.wikipedia.org/wiki/RLC_cir...
Special Thanks to all my supporters on Patreon! Especially @afiskon !
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[@carlosdiaz4535]

Can't get tired of your videos, I've been watching them the last couple of weeks and learned more than in school and work, you got a great mix of simulation, theory and hands-on in electronics. Kudos to you.

[@FesZElectronics]

I'm happy these are useful! Thank you!

[@m1geo]

I don't think I've ever seen a simulation and practical measurement agree so closely before! Nice work! 👌

[@homemade83]

keep going , you are different.

[@remy-]

Ok. From ‘just add a 10n cap’ to easy understandable science by you. Thanx! 🙏🏻

[@Bianchi77]

Nice information, thank you for sharing it with us, keep it up :)

[@FF7824]

Very instructive and well presented. Thanks!

[@hernandariocostantini5420]

Excelent video.....

[@BalticLab]

Oscillations in a nutshell: When you don't want them, you get them. When you actually want them, you don't get them. 🙂

[@FesZElectronics]

This should be one of Murphy's laws :D

[@rul1175]

A treasure of a video. Subscribed and thumbs up.

[@thearithmos3408]

Nice job, you really deserve more subs.

[@KamleshGadhvana]

thanks for this solution very nice work

[@cannesahs]

Really good video.

[@profpoochie]

Thank for very nice tutorial.

[@FesZElectronics]

Glad it was helpful!

[@q12x]

Nice explanation

[@iblesbosuok]

Excellent

[@louco2]

Are you considering the 360mv the voltage drop across the capacitor/ESR? Because in my mind it should be U_supply-V_drop (8.5v-0.36v)=voltage across capacitor/ESR.

[@jaredgray7872]

Thanks for the video! I like how you go from theory and formulas to simulation to real life. I'm curious, have you used micro-cap before?

[@FesZElectronics]

Not really, but that program has been recommend to me before. Simulation results should be the same from any spice simulation program but at the moment I am most familiar with LTspice so I stick to that.

[@chandrashekarg2073]

How to measure dv/dt of capacitor ?

[@mrlajel]

Hi Fesz, what do you mean about the inductor, is it a part of equivalent circuit? or is it added to the circuit as a part of decoupling mechanism? thank you.

[@FesZElectronics]

Both I guess; an inductor is part of the equivalent circuit of a capacitor, and this is detrimental to its filtering ability; but an inductor can also be added in series with the power line to form an LC filter with the capacitor. The inductor built into the capacitor cannot be changed, while the one added in the LC filter is up to the designer to chose a value.

[@christopherwolford6522]

I don't have an o scope, looking at making one from stm32 or ATmega32u4, but I'm not sure how much of an o scope I need. What type of range would I need for small examples like this? Thanks. Edit: I would like to build small little led / other smps dc to dc converters from ground up and maybe take old psu for PC and build a cheap lab psu. I'm working on small stuff and working on setting up a home lab.

[@FesZElectronics]

I guess the biggest limitation in a uC based scope will be its bandwidth. What do you expect to get out of your circuit? I could not say what is an ideal BW for my examples, you can usually fine-tune the experiment to work at lower frequencies - this can be simulated in LTspice first.

[@christopherwolford6522]

@@FesZElectronics thank you, that's what I was thinking. Currently I am wanting to dive in to smps and dc to dc buck and boost. With $10 stm32 I can push 1.5 to 2MHz, with the ATmega good to about 50KHz. Note this are dso. I would love a nice one, but time and money don't justify. Last I used an o scope was 3 years ago in an intro circuit class. Thanks for the response.

[@maksymkloka5016]

I searched the internet far and wide ... can't seem to understand where the C=L(Zt^2) came from. Any chance you could assist.

[@FesZElectronics]

I don't remember exactly but I think its the damping factor equation where R is replaced with Z and the damping factor with 0.5; so to have a clear underdamped condition.

[@mojtabajamal3457]

hi ...you are very perfational.

[@paulwary]

Think you mean 'professional'? I agree!

[@aa-bu7ml]

[@debmalya6144]

So just adding more capacitors are not always good idea

[@crazyham]

⚡🙏⚡ Awesome Channel Thank You ⚡🙏⚡