Hello All About Circuits.com community!
First off I want to say what an amazing site! I am a 2nd year student at the University of Hartford double majoring in Computer Engineering and mathimatics. This site puts the textbooks I purchased to shame!

Anyways I have a quick question, if anyone on this message board is a practicing engineer, do you actually mathematically model circuits you design? I am constally bombarded by my professors telling me how when one gets an engineering job, how vital my knowledge of differential equations will be. And how we will constantly be modeling every circuit that is designed. The way they talk about it seems kind of silly to me soooo, I was just curious. I mean I understand of course that it is important to learn inorder to understand where concepts come from and where they are founded but the extent my professors talk about just seems strange.

 

I think they might be just a little bit full of themselves.

 

how vital my knowledge of differential equations will be. And how we will constantly be modeling every circuit that is designed.

No, not usually.

The main thing that students (and even some experienced people) need to understand is that a nominal design is not a complete design, that one must look at and consider component tolerances and physical properties (temp, vibration, etc). One should design a circuit, and look at all the corners (do the math) to create a robust design.

For instance, take a "simple" circuit such as using a 5V zener as a shunt to make +5V from a +8V input. As a nominal design you would select a series resistor to drop the difference and limit the current to some amount. But the series resistor is going to have a tolerance, the diode will have a tolerance, and both will be affected by temperature. It would be easy to say that you are going to get +5V at 10mA for instance, but what you could get (especially in a production environment where the circuit is replicated hundreds or thousands of times) is possibly anywhere from +4.5V to +5.5V across temperature.

So, let's say you were going to power a few TTL type circuits with this power supply ...would it serve it's purpose all of the time? Does it meet design specifications? Probably not, because +4.5V is a bit low, and +5.5V could destroy the IC's. So, if you were unwaringly satisfied with the nominal design (+5V), there would be times when IC's are burning -- much to your chagrin, and exasperation of various people depending upon your design.

Another side of this design example would be the amount of shunt current going through the zener vs. power dissipation. It may be fine at, or near room temperature where most hobbiests live, but what if the ambient temp is +70C, or -40C ? Is the zener going to survive, or operate as you expect it to?

It is common to engage in circuit simulation to help confirm or support ideas and calculations, because simulation tends to be easier and cheaper than building a circuit and fiddling with it later.

But most of the math doesn't go beyond, albeit sometimes complicated (or tedious), electronic's algebra. There can be times, or certain applications, where calculus is useful.

 

Thanks for the comments about the site.

I guess the short answer here is what job you ultimately go into; for example if your job centres around electromagnetics you will come into contact with differential equations on a regular basis, however if you are working on embedded design or programming then you are unlikely use differential equations.

The most important point is that you are confident enough to work through differential equations on your own should you need to use them on on of your projects. The reality is that in this electronic-world most of your needs will be met with softwares.

Personally, I have written a TLM solver for modelling RF and MW field interactions with dielectric materials. The TLM method is a differential equation method for solving Maxwell's Equations (and 1-dimensional thermal equations) using circuit equivalents. So in answer to the question, "Do you actually mathematically model circuits you design?" I don't design them, but in my job I do model the physical systems I design for.

Dave

 

Thanks for the comments about the site.

I guess the short answer here is what job you ultimately go into; for example if your job centres around electromagnetics you will come into contact with differential equations on a regular basis, however if you are working on embedded design or programming then you are unlikely use differential equations.

The most important point is that you are confident enough to work through differential equations on your own should you need to use them on on of your projects. The reality is that in this electronic-world most of your needs will be met with softwares.

Personally, I have written a TLM solver for modelling RF and MW field interactions with dielectric materials. The TLM method is a differential equation method for solving Maxwell's Equations (and 1-dimensional thermal equations) using circuit equivalents. So in answer to the question, "Do you actually mathematically model circuits you design?" I don't design them, but in my job I do model the physical systems I design for.

Dave

ah very interesting, thanks for the feedback. I was debating double majoring in Computer engineering and electrical engineering but decided to go with computer and mathematics because I figured if i knew the math then all concepts assiocated would come easy. So I suppose it sounds like its a good idea to be well learned in it but its not widely used as my professors claim it to be.

thanks everyone

 

You should consider moving towards the engineering direction, especially if you want to do anything practical. You can stick to math and computers, as long as you prove to employers that you can actually design things.

What do you like to do? Just follow what you like, then it will pay off since you'll probably be good at it and you'll enjoy it as well.

Steve

To me ,differential equations are just part of math.. Everyone knows math is important, why not include high level math too?? If you take a modeling and numerical methods, you'll appreciate it!