Maker Pro
Maker Pro

Book: Transistor Circuit Design, With Experiments, by Delton T. Horn

Nisar-von-Voltenbräackter

May 23, 2018
36
Joined
May 23, 2018
Messages
36
I got this book and liked how it was well-written. Then errors start showing up, making the book more of a challenge than a walk in the park. Has anyone read it? It was published in 1985 by the prolific electronics writer, Delton T. Horn.
 

Nisar-von-Voltenbräackter

May 23, 2018
36
Joined
May 23, 2018
Messages
36
Looks like I'll have to read it again. I found it in a day's time, so I'm sure I can find it again. Until then, it may have to wait.

According to where my notes ended, on p. 115 it seems that I may have had trouble following the Rq equation and then went on to discover an important omission in an equation elsewhere.

That was when I began to look for anything, anything about this book -- a new edition or an associated erratum from the publisher -author team. However, nothing turned up.

I do know I really want to find that equation and follow up. I'll try to get that posted ASAP.

...specifically?
 

KJ6EAD

Aug 13, 2011
1,114
Joined
Aug 13, 2011
Messages
1,114
Textbooks are a good option to avoid high error rates as they go through frequent updates, mostly for cynical profiteering reasons, but with the positive side-effect of getting the errors wrung out after several editions.
 

Nisar-von-Voltenbräackter

May 23, 2018
36
Joined
May 23, 2018
Messages
36
...specifically?

After an absence, I've begun to re-read this design book again. I'm sure to encounter more, but this was where rather sizable errors crept inin, c. pg. 100.

First, in the 'Alpha and Beta' section (p. 94+), we learned to approximate the beta when collector current isn't known, by using emitter current where β ≅ I.e ÷ I.b since normally β = I.c ÷ I.b

Discussion of Common-emitter transistor configuration commences on p. 98. Base current controls product of transistor of this configuration, itself taken from Collector.
Be aware of transistor as current-controlled device. Although DC voltages fix its operating-point, where its Collector must be the most positive and its Emitter must be the most negative for the NPN being virtually boarded.

Summary of intentions:
Calculating base voltage and base current for a transistor under one of three configurations isn't a bad idea to learn. The text tries to show variables involved in a base voltage tally then goes in to conclude the formula with another quantity, emitter current, I.e. And as both variables relate as matter of one compending formula's commutative attribute, any quantity I or V can be calculated for base or emitter. And then the approximation method shows how collector voltage or current can be calculated by swapping near-equivalencies, I.c for I.e.

Problem 1:
On p. 100, formula to calculate base-voltage leaves out the /β then puts it in again. Then variable for emitter current I.e vanishes without rhyme nor reason from a stage of the equation.

Although I do not follow the math after mid-page, I grasp the upcoming switch from I.e ≅ to I.c ≅ after the produced equation.

Then the text goes on about leakage currents I.cbo and I.ceo. The text appears to be using the approximated formula for the beta. But the value can be calculated by referencing a chart that details I.c and corresponding I.b given V.cc value.

Problem 2:
For the text to introduce leakage current in this approximated way, it leaves me wonder whether it aims to be a fancy way to get the difference between I.c and I.e accounted for. But I tend to think not.

Yet we know the leakage current derives from there being some current that flows despite model for an ideal PN junction. Of course there is no trouble using what I presume to be "load line" charts to arrive at leakage current calculations. I think the references include "collector-base open" and "collector-emitter open," or open-beta and open-alpha currents, respectively. The author says that these matter in rarer designs.
 

(*steve*)

¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd
Moderator
Jan 21, 2010
25,507
Joined
Jan 21, 2010
Messages
25,507
Why not post an image of a page that has errors?

From your description, some of the problems could be anywhere between real and your misunderstanding.

Given that nobody has piped up saying they've read the book, short of finding a copy in a public library or buying a copy, there's not much we can do.
 

(*steve*)

¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd
Moderator
Jan 21, 2010
25,507
Joined
Jan 21, 2010
Messages
25,507
Other books of his are not to be "replete with errors". There is some suggestion of a web site with corrections. I'd go in search of it. Some suggest is hosted by the publishers -- might even be worth contacting them.
 

Nisar-von-Voltenbräackter

May 23, 2018
36
Joined
May 23, 2018
Messages
36
Done! (If illegible, I'll shoot it again -- this time with some assistance.)
 

Attachments

  • IMG_20181007_163547_hdr_kindlephoto-669246517.jpg
    IMG_20181007_163547_hdr_kindlephoto-669246517.jpg
    128.5 KB · Views: 20

(*steve*)

¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd
Moderator
Jan 21, 2010
25,507
Joined
Jan 21, 2010
Messages
25,507
Beta appears to be present in every equation it should be.

Your photograph is a bit fuzzy, but I can make most of it out. I have to assume what some of it is though, so a better photograph might allow me to find problems.
 

Ratch

Mar 10, 2013
1,098
Joined
Mar 10, 2013
Messages
1,098
Be aware of transistor as current-controlled device.

No, a BJT, FET, and a vacuum tube are all voltage-controls-current or transconductance devices. The physics of the device proves the above statement to be true. Show me something that says a transistor is current-controlled, and I will show how it is wrong.

Ratch
 

(*steve*)

¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd
Moderator
Jan 21, 2010
25,507
Joined
Jan 21, 2010
Messages
25,507
Ratch's observations are irrelevant to the approximation being discussed in this book.

Ratch's is the sort of person who, if you were to post a photo showing a rule next to an object for scale, would argue that it didn't tell us anything unless we know the relative speed of the items.
 

Ratch

Mar 10, 2013
1,098
Joined
Mar 10, 2013
Messages
1,098
Ratch's observations are irrelevant to the approximation being discussed in this book.

Ratch's is the sort of person who, if you were to post a photo showing a rule next to an object for scale, would argue that it didn't tell us anything unless we know the relative speed of the items.

I aver that it is relevant. That false factoid by the author is not a misprint or oversight. It is an indication that he does not really know some of the basics of how semiconductors operate. The OP is correct for being suspicious of the rest of the material in the book, and does well in checking and proving the remainder of what the author disburses.

Ratch
 
  • Like
Reactions: LvW

Ratch

Mar 10, 2013
1,098
Joined
Mar 10, 2013
Messages
1,098
I'm surprised the time limit kicked in before I could clean the extra BBCODE up.

Yes, there is a mistake in the book whereby Ic is not divided by beta. Also he should compute the current directly instead of deriving a formula. You could run yourself ragged by deriving thousands of formulas to thousands of problems. Whereas, if you know how to calculate the values wanted, you only have to know the method. Can you find the solution without the formula, or do you need assistance?

Ratch
 

(*steve*)

¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd
Moderator
Jan 21, 2010
25,507
Joined
Jan 21, 2010
Messages
25,507
Equation 1 uses Ie instead of Ic. Using the former makes the calculations easier. In fact it will later be changed back to Ic. The difference is the base current, which is typically explained away as being "small compared to Ic". The same style of simplifications are seen in many other calculations in electronics.

Equation 2 has IB instead of Ib

Equation 3 has Ie x Rb instead of Ib x Rb

The next paragraph should start with "These equations" because there are now 2 equations. Equation 2 is a rearrangement of equation 1, equation 3 is a new equation.

In equation 4, 2 steps have been performed. Firstly Ib has been replaced by Ie/β, then Ie/β x Rb has been rearranged to Ie x Rb

What @Ratch is banging on about is that it is Vbe is determined by Ib and Vbe determines Ic. This is not in dispute. (There are a multitude of other variables involved that I will ignore for simplicity)

However, you end up with 2 equations, one showing the relationship between Ib and Vbe and another relating Vbe to Ic. Combining these you can find a relationship between Ib and Ic. This relationship can be assumed to be linear over a range of operating conditions yielding the equation for β.

The problem with β is that it varies (I.e. the equation isnt linear). The benefit of
β is that it allowes you to make simple predictions of behaviour that are typically close enough.
 
Top