Відео

in a dc/ac analysis

​@@chrissanthakumar1382 I used to tell my students to think of a windshield/windscreen wiper (DC, AC). Start at the first stage to establish the initial DC bias and then follow this through stage-by-stage to the output. Now that you have all of the required DC values, go to the final stage and determine its voltage gain and input impedance. Then go to the prior stage, using the Zin you just found as the load. Once the penultimate stage is done, repeat the process for the stage before that, and so on. The next time you're driving in the rain, just imagine that the wipers are making a sound that goes "DC, AC, DC, AC..." ;-) Anyway, more on this in my free Semiconductor Devices text. Follow the links in the description to download it.

Go to 21:00. There is a still frame of the entire page. It turned out that very little was chopped off, but I understand that it can be disconcerting.

No, I have not addressed shielding in this video. It's an introduction to the topic, not an exhaustive treatment. It is important to the design of such instruments, as you say, and perhaps I'll have time to cover this in a future video.

Glad you liked it. Tell your pals!

I would tend to agree regarding this video, but some people have told me that they have a hard time keeping up because I talk too fast. It's a Goldilocks thing, I guess.

@@ElectronicswithProfessorFiore It's all good :) Really enjoying these videos. Subbed.

You have to fit it into your design requirements. Like most engineering, it's a matter of trade-offs. You have to balance the various parts. Once you understand what the component does, you can start playing with it to fine tune it. In this case, an increase in the swamping resistor will reduce distortion, increase Zin, and stabilize gain (generally good). On the down side, it will lower the gain. One place to start is "Just how much gain do I need?" This assumes that the non-swamped circuit has more gain than is required. You can then add resistance to bring the gain down to what you need, and in the process, see how well that change improved other factors. I should add that, when I make videos, I often choose convenient component values (i.e., convenient in the sense that you can do the calculations in your head, like having a 1.8k and 8.2k that adds up to 10k), so don't use these as a design goal. Back in college I had a calculus prof who would say "I like things to work out to one-sies and two-sies". IOW, why have the exercise work out to an answer of 3 pi over 17 when it could be 2 and you never have to pick up a calculator or pen? As long as they both illustrate the process, use the simpler one.

Glad you liked it. I remember thinking the same thing when I was first learning about op amps decades ago (when they weren't nearly as nice as what's available now). I never liked to learn things as a "black box". It's immediately functional, but it doesn't take you into the future.

@@ElectronicswithProfessorFiore I have almost a year of trying to learn electronics. It feels overwhelming sometimes, just soo much to learn lol.

Welllll, sometimes they mix, like if you're doing pyrotechnics for a metal band. But generally, speaking, if your guitar amp or loudspeaker catches fire, you're probably doing something wrong. Just a suggestion, mind you. ;-)

In that case, download my free textbook, Semiconductor Devices (link in the description). You will find more info on this topic.

@@ElectronicswithProfessorFiorethank you!

"Voltage" is a generic term indicating a potential difference. A power supply is a fixed DC voltage source, for example, a battery. Ideally, its value never changes. The other voltages referred to are those potentials seen across various components such as resistors or transistors. Their voltages will depend on the supply voltage(s). Sources generally are considered as voltage "rises" while the voltages across resistors and the like are generally considered as "drops".

Those are videos that I am working on or which have been queued up for scheduled release. Don't worry, you'll see them eventually! Everything on this channel is available for everyone. There are no "tiers" or "support levels" or anything like that.

@@ElectronicswithProfessorFiore Thanks for the prompt response. I’m loving your instruction and what I’m learning from you. I wouldn’t want to miss out on some cool material!

This is a common questions that I get. There is a rationale for this. First, I don't include answers to all problems because these texts are used at colleges and universities, and professors assign some of these problems for graded homework. This is particularly true for the challenge and design exercises. Second, if you have doubts, remember that you can always capture the circuit in a simulator to check the results.

There's nothing magic or special about 1 Hz. The choice of critical frequencies will depend on the application. In general, yes, you can look at those capacitors as shorts for higher frequencies. That is an idealization, of course. The reactance of real-world caps do not follow the Xc formula as frequency increases to infinity. Secondary effects come into play.

@@ElectronicswithProfessorFiore Thankyou sir

Sure, but two things to consider. First, there are a lot of older discrete designs out there that might need to be repaired at some point, and second, whether or not a design uses discrete or integrated circuitry, someone (or some group) has to do the initial design and testing. If people only know how to replace ICs and no one knows the theory, there can be no progress. This goes back to the argument of the value of education versus training.

@ElectronicswithProfessorFiore I have no problem with learning theory. I did. But with all new designs of electronic devices having ICs, CPUs, SOC, and IC audio amps, and perhaps more, discrete designated are becoming a thing of the past. True theory about say repairing an old radio would be helpful.

@@roncaruso931 And if that old radio uses a discrete class B output, what then? ;-) Besides, like I said, who is going to design the ICs that (internally) use a class B stage? Further, that new IC might use a class D output, but again, someone had to design that, even if all the repair tech does is replace said IC. Taking the opposite approach is a little like saying that no one needs to learn how to write code anymore because you can find lots of code already out there. All you have to do is patch it together. (sorry, no.) For that matter, why does anyone need to learn a musical instrument when they can just sample existing music and then edit and rearrange it? I think there is value in starting with the fundamentals in order to build a strong foundation, and working forward from there. Too many people try to skip that in order to get to "the latest and greatest", but the results are usually less than exemplary. If it's not obvious yet, this channel exists to help support people who are trying to learn the material from the bottom up. It is NOT designed for people looking for a video with just enough info on how to fix "X" with minimal knowledge. I think there are a sufficient number of those channels kicking around. And if that's what someone is looking for, I say all the power to them and have at it!

@ElectronicswithProfessorFiore I agree with you about old radios. But eventually, even old radios will be discarded. Today's young generation are not interested in saving these beautiful old analog radios.

No, that's the TINA-TI simulator. Wrench has a DSP version of these bass and treble controls (with adjustable corner frequencies). It also has fully parametric EQ and graphic EQ. You can do spectral analysis of signals but it won't draw Bode plots like TINA-TI.

Thanks for the prompt reply

Determine your lower frequency limit and then use the standard fc=1/(2piRC) formula. R is the Thevenized resistance around Cby (R1//R2//R3 to a first approximation).

Wellll, I'm not so much a "guitar nerd" as I am a "science and music nerd". Definitely more on the percussion side than the stringed instruments side. There's lots of stuff here, so enjoy!

If you cascade a bunch of NPNs, the collector voltages keep increasing from one stage to the next (Vc must be greater than Vb for an NPN). Eventually, it will hit the power supply. The opposite is true for PNPs, so alternating them produces Vc values that stay in the middle.

@@ElectronicswithProfessorFiore thank you !

Yes, the cap acts like a short at these frequencies and that's why the 150 is in parallel with the 3.3k (remember, the DC power supply is an AC ground). That combo is pretty close to 150, though. And yes, this resistance does act like swamping in that it will lower distortion compared to a typical CE amp.

@@ElectronicswithProfessorFiore okay thank you!

Thanks for the compliments. I have no intention to charge anyone anything for what I have learned through my career. I was paid to do that for over 40 years. Now I do it because I like to and because I believe that no one should be denied education due to their financial constraints. I absolutely agree that employers care more about results than on most other factors. This is one reason why cheating during formal studies is self-defeating. In the long run, it doesn't matter if you passed the tests if you can't also perform the work.

Yes. Slew rate effects will be more pronounced on higher frequency signals though (assuming same amplitude).

@@ElectronicswithProfessorFiore Thanks

Without diving into it, I suspect that is due to the finite time resolution of the sim. Note that we have zoomed into the plot. Time domain plots only compute a certain number of points. Having said that, you will sometimes see slew limiting that changes slope. This is due to the internal characteristics of the op amp.

The feedback network is series-parallel which produces a gain of 1+ Rf/Ri. This is not an inverting amplifier. The input (such as it is) comes through the RC network into the non-inverting terminal.

@@ElectronicswithProfessorFiore Sorry about that.. I thought I deleted the comment. I answered my own question shortly after I posted it. But thank you!! I got the SP/PP and inverting/non-inverting concepts mixed up. All good now. :)

@@JohnJohnson-ml2ll Cool!

You could use them. The cap charges up to the peak value and then holds that potential. When you compare the discharge time constant to the input frequency, you see that the cap voltage is fairly constant. Essentially, it behaves like a battery, adding a DC offset.

@@ElectronicswithProfessorFiore I see, thankyou professor!

When you add the bypass cap on the divider, without R3 the Zin would be zero. Ideally, the junction of R1, R2 and the bypass cap would be at ground. Adding R3 prevents that from being the case for the input signal. R3 winds up setting Zin.

Oh I see, Thanks a lot.

Not quite sure what you're asking. A composite could refer to an op amp made from discrete components (versus integrated).

TINA-TI from Texas Instruments. It's free.

Glad you're enjoying it!

If I understand you correctly, you're asking for the same sort of circuit but with a positive slope, right? I am not sure that you could make one as simple as this little first order circuit. I'd have to think about that for a bit. I can't recall seeing one.

@@ElectronicswithProfessorFiore Yes, exactly. I'm looking for such allpass filter because I want to cancel out the phase shift caused by a preceding highpass filter. If possible then we can get a hp filter with flat phase response. But maybe such allpass filter is impossible in principle?

@@siarez It sounds like what you want is constant group delay or linear phase for your filter. In that case, I'd suggest looking at standard active filters using a Bessel alignment instead of the usual Butterworth (check the videos in the Op Amps playlist or chapter 11 of my free op amps text). A 2nd order Sallen & Key wouldn't be much more complicated than the circuit in the video above (as in another cap and maybe another resistor).