World Scientific Publishing is marketing my book. They have put out a flyer for several of their electronics books (https://www.worldscientific.com/pb-assets/wspc-site/catalogue-pdf/Electrical-Electronics-Engineering2024-25-1705395593457.pdf), and my book is the first one on the flyer!
Of course, they don’t mention that the PDF for the book is also available on LeanPub for only $7.99 (https://leanpub.com/applied_analog_electronics), but I wouldn’t expect them to.
I have decided to put my book on sale for the traditional American sale season, but I’m too lazy to remember to synchronize to midnight Thursday night. So I’ve reduced the minimum price from $8 to $6 (well, from $7.99 to $5.99) starting now, and I’ll raise it back up in about a week.
No coupon needed: just go to https://leanpub.com/applied_analog_electronics and pick the price you want to pay.
Sigh, just as I’m finishing my textbook, I find out that publishers don’t want new textbooks. I did have one feeler from Springer, whose book prices are high and royalties low, and they wanted me to provide camera-ready copy. What were they going to do as publishers, other than keep almost all the money?
I have been self-publishing drafts of the text book in PDF format through LeanPub. I can sell the text for about $10 and make more money per book than if a publisher sold it for $80. I have a new version that I tried to put up on LeanPub last Thursday, but I ran into a problem on their web site in changing the URL, and I’m waiting for them to fix it. They were able to reproduce the problem and have told me that fixing it is a high priority, so I’ll probably be able to release the new version early this week (maybe 2018 Dec 17 or 18).
My big problem for the textbook is marketing (whether self-publishing or through traditional publishers)—how do textbook authors get other instructors aware of their book and willing to try it in a course? Because my book takes a somewhat different approach to teaching electronics than the standard university course (which does about a year of applied math and circuits before doing any design), it isn’t a direct replacement for existing texts, but requires some redesign of curriculum. That makes it an even harder sell, though I think that my design-early approach to teaching engineering is more in line with pedagogical research.
I’ll be releasing an updated version of the Applied Electronics for Bioengineers text on LeanPub today. I’ll probably raise the minimum price next week, to reflect the improved quality, but I’ll give people a few days to get the book at the old price. (Remember that the LeanPub model allows you to get all future editions of the book free, as long as I continue publishing through them, so there is no reason to wait until a new edition comes out.)
I’ll list the changes in two sections: changes that were made since the October 2016 release, then changes that were made in the Oct 2016 release (because I don’t seem to have posted those to the blog).
This post is a continuation of Having trouble learning Lagrangian mechanics, looking at electronic systems rather than mechanical ones. Again, this is not intended as a tutorial but a dump of my understanding, to clarify it in my own head, and to get corrections or suggestions from my readers, many of whom are far better at physics than me.
For electronics, I’ll use charge 
Some notation:
is the difference between kinetic and potential energy of the system. The potential energy will be the energy stored in capacitors, 
, and the kinetic energy the energy in the inductors, 
. (Note: that is only self-inductance. If we have mutual inductance 
between two inductors, we need to use 
for the kinetic energy—I’m a bit confused by that, as we could have negative kinetic energy. I rarely use inductors or transformers in my electronics, so I’ve not had to work out my confusion yet.)
is the power dissipated by the resistors in the system: 
.
is the vector input to the system needed to make the energy balance work out. By using charge for each coordinate, the units here will be volts.With this notation, the basic formula is
Let’s check the units:
, which is indeed volts.
, which is also volts.
, which is again volts (Ohm’s Law).Now all we need to do is to figure out which 
Simple RLC series circuit with a voltage source.
We can use a single coordinate, the charge on the capacitor, 
For electronics modeling, we often want to look at the ratio of two different voltages in a system, for example, the output of a filter relative to the input to a filter. How do we set that up? Let’s look at a very simple low-pass RC filter:
The upper schematic shows the normal way to represent the low-pass filter. The lower schematic shows it with a voltage source and a voltmeter, with two loops (one of which has no current).
The potential energy is just 
In other words, we get the voltage at the voltage source and the voltage at the voltmeter. If we want to do anything with these equations, we need to recognize that the 
If we take Laplace transforms, we get 
I could do another, more complicated example, but I think that the idea is clear (to me):
I don’t find this process any simpler than using complex impedances and the usual Kirchhoff laws, but it isn’t much more complicated. It may be easier to use the Lagrangian formulation than setting up the equations directly when there are mutual inductances to deal with—I’ll have to think about that some more.
Of course, the big advantage I’ve been told about for Lagrangian mechanics is in electromechanical systems, where you model the mechanical part as in Having trouble learning Lagrangian mechanics and the electronic part as in this post, with only a conservative coupling network added to combine the two. It is in setting up the coupling network that I get confused when trying to model electromechanical systems, and I’ll leave that confusion for a later post.
Gas station without pumps 