Electronics Technician magazine 1966

[Ritchie200]

Found this working my way to end of the internet.  Pretty interesting with articles about tracing issues in SS and tube amps.  So, if you are having problems sleeping, this could be a good read!

Jim

https://www.americanradiohistory.com/Archive-Radio-Retailing/60s/Electronic-Technician-1966-05.pdf

[shooter]

duly archived when my computer quits sweating 
I went looking for the end of the web a couple years after www.
all black page morphed into a dungeon door, it opened with "Welcome AND my FULL name " I was so scared I jerked the power cable, pulled the drive, waxed in an MRI, then reloaded virgin SW!
I quit lookin 

[shooter]

started my 1st pass at negative resistance 
glazed over about a 1/3rd the way through... 
I never got the concept well the 1st time through, maybe 40yrs latter 

[Gnobuddy]

...negative resistance...never got the concept well...

Perhaps this will help: you know how the voltage from your car battery droops (falls) when you crank the starter? The voltage falls because of voltage drop in the battery internal resistance, right? The starter draws lots of current, and some voltage is lost inside the battery, because of internal resistance. Mathematically, the voltage you get is Ebattery - I * Rbattery, where Ebattery is the unloaded battery voltage, and Rbattery is the internal resistance (and "I" is the current being drawn.) The minus sign tells you that the voltage you get will fall as the current "I" increases.

Now imagine a battery that had negative internal resistance. If you draw current from it, the voltage doesn't fall - it rises instead. By the same amount as before - Ohm's law still applies. But the *sign* is different. Now you the voltage you get at the terminals is Ebattery + I*Rbattery: a plus instead of a minus.

Now imagine reducing the battery voltage gradually, until the battery voltage is zero volts...what you're left with is a pure negative resistance (which doesn't exist in nature, but you can force an op-amp to behave like one.) When current flows through this negative resistance, you get a voltage increase instead of the usual voltage drop. The algebraic sign is reversed.

Did that help any?

-Gnobuddy

[PRR]

FWIW:

You can wind a car generator for negative resistance. Put part of the field coil in series (I think) with the load. As load current rises, field strength rises, voltage goes *up*.

While that would be wrong for a car, it is done in large power generation stations with long distribution lines of significant (positive) resistance. Done just-right, when 20KV at generator would sag to 16KV at substation, instead the generator rises, "anti-sags", to 24KV making constant 20KV at substation.

Obviously there must be limits or the generator would smoke and burn.

[shooter]

I could do imaginary #'s, -R etc but it still strikes me as a "gimmick"
I went side-ways early on when the teacher tried her best to make me believe little betty has 5 apples, little billy has 6 apples.  Now class we take Billys 6 apples and subtract them from bettys 5 and wanted me to buy in that we now have neg 1 apples 
from the article they even say "of course they don't really exist"
Until I can eat a neg apple or buy a neg R  I'll leave the spooky math to the really dedicated math folk n stick with the physical world for worldly things 

[PRR]

A welding arc is a negative resistance. The hotter it gets, more current at less voltage.

Tetrodes have a negative resistance zone, and this was used occasionally to build oscillators.

Then there is the Tunnel Diode, with a distinct neg-res zone, highly touted when new but seems to have only been used in odd corners of extreme gear. (Its descendants serve as detectors/mixers in radio astronomy.)

[Gnobuddy]

Until I can...buy a neg R...

I bet you've already bought a few negative resistances.

Every buy an NE2 neon bulb? They have a negative resistance region (which is why you can make a nice oscillator with one.)

Got any light-dimmers in your house? They usually contain a triac (which has a negative resistance region), and a diac (which also has a negative resistance region.)

When I was about eleven or twelve, I was trying to make my own turntable at home, and one of my biggest headaches was that the motor wouldn't maintain a constant speed. When the pickup stylus was at the outer edge of the record, there was more load on the motor, and it would slow down because of its internal resistance. When the stylus reached the center, there was less load on the motor, and it would speed up.

I started hunting for a solution, and that's when I first heard about negative resistance. At the time, there was a two-transistor circuit used in many cassette decks and turntables to maintain constant speed from a DC motor. The circuit worked by inserting a negative resistance in series with the motor: just like PRR's substation example, if you match the external negative resistance to the positive resistance already inside the motor, then the speed variation goes away, and the motor speed becomes (nearly) constant irrespective of load (within reason).

Ohm's law itself is an abstraction - you can't see, smell, touch, or hear current or voltage or resistance, after all, and you can't go out and buy a volt. Electrons are real, but we can't see or feel them directly either. Electronics is full of invisible abstractions you can't pick up and look at. Changing the sign of the voltage from minus to plus is just one more of those little abstractions.

I think all the abstractions are actually one of the reasons I enjoy electronics - it makes it all the more magical when you strum your guitar and sound actually comes out of the loudspeaker! 

-Gnobuddy

[jjasilli]

I could do imaginary #'s, -R etc but it still strikes me as a "gimmick"
I went side-ways early on when the teacher tried her best to make me believe little betty has 5 apples, little billy has 6 apples.  Now class we take Billys 6 apples and subtract them from bettys 5 and wanted me to buy in that we now have neg 1 apples 
from the article they even say "of course they don't really exist"
Until I can eat a neg apple or buy a neg R  I'll leave the spooky math to the really dedicated math folk n stick with the physical world for worldly things 

I had the same problem.  For me it was cured by scuba diving: 10 feet under water = -10 feet.  You can "have" a negative apple.  It's an unusual way of saying that you owe someone an apple. 

[shooter]

For me it was cured by scuba diving: 10 feet under water = -10 feet.

unless you start by saying I'm gonna be 27ft off the bottom then it becomes a + Einstein made me smile when I lernt he believed everything is relative

as to

negative resistance region

someone in the lab says hey Bob, watch this, I can make I go up, AND V, wow ohm was wrong, we can make a million!  let's run it past the math geeks, n they come back and say dumb-e, just add a - sign and the world works 
like I said, I had to endure all the calculations for 1/0 = -I, forcing ohm with signs, ettal, and NO I'm not a flat earthier, I believe we landed on the moon, and ALL the stuff that works but needs extra help using "creative explaining" AND I truly believe it "made me"  skeptical (a good thing) so in the end, the teachers did their job by having me question n not just accept, that's why I like here 

[Gnobuddy]

You can "have" a negative apple.  It's an unusual way of saying that you owe someone an apple.

I'm looking forward to a negative number in my bank statement - a tax refund I'm expecting. 

-Gnobuddy

[shooter]

a tax refund

don't even get me wound up on govmt arithmetic 
I saved the tax payers some k-dollars in my 1st quarter from our work-center budget, instead of a party I got hauled into the BIG folks room, told I can either SPEND that "savings" or I can give up a stripe, become a general laborer instead of radar tech AND kiss ANY hope of career away
btw, the Govrmt's the one that told me it's no problem dividing 1 by 0 we call it imaginary numbers 

[Gnobuddy]

...either SPEND that "savings" or I can give up a stripe

Part of my job involves dealing with an equipment purchasing budget. I got the same unofficial memo you did: make sure to spend it all every year, or your budget will be reduced for the next year.

the Govrmt's the one that told me it's no problem dividing 1 by 0 we call it imaginary numbers 

Somebody got that terribly wrong, but we'll let it lie, since you obviously want no part of it.

I saw on another thread that you're an artist. My wife is, too, and she wouldn't like imaginary numbers either. I "get" imaginary numbers, and am glad that I can use them to calculate a tone-stack frequency response. But I can't understand how an artist like you or my wife can use opaque paints to paint a transparent bottle into a painting.  

If everyone had their brain wired like mine, there would be no art or sculpture, all clothing would consist of a towel wrapped around us, and life would be much more drab. And if everyone had an artist's brain, the world would be full of beautiful and thought-provoking things, but there would be no tube guitar amplifiers or computers or Internet or bridges longer than a single tree-trunk. Good thing evolution likes diversity!

-Gnobuddy

[shooter]

brain wired like mine

I got a near perfect 50/50 split, and during the "transition" from logic to artistic or back, life gets kinda wonky for a few days 
and using opaque to paint glass is an artistic illusion just like a negative resistor is in reality an illusion to make the math n science work smooth so everyone's happy 

[MakerDP]

Very cool. Would like to read the follow-up articles mentioned in the article on compressors!

[jjasilli]

all clothing would consist of a towel wrapped around us
Toga Party!!! 

[Ritchie200]

For me it was cured by scuba diving: 10 feet under water = -10 feet.

unless you start by saying I'm gonna be 27ft off the bottom then it becomes a + Einstein made me smile when I lernt he believed everything is relative

 

Jim

[Ritchie200]

Very cool. Would like to read the follow-up articles mentioned in the article on compressors!

I know!  However, that was the only copy/issue I could find.    Maybe someone can find some archived.

Jim

[jjasilli]

Geez, if the Serpent gave Eve a negative apple, we can guess that the future would surely be very different.

[Ritchie200]

He did!  You do realize all us Adams have been trying to repay that debt forever!

Jim

[shooter]

if the Serpent gave Eve a negative apple

Yup n if the teacher woulda just stuck to numbers I woulda just went along with it, but when she brought in "the real world" and wanted me to buy into neg apples it was all over 

[PRR]

> the only copy/issue I could find.    Maybe someone can find some archived.

Shorten the URL and see what the home of the website is.

https://www.americanradiohistory.com

Ah-ha. Bunch of magazine scans.

TIP: go to the "A-Z" box and try "E" for Electronics Technician. (Sometimes you have to grope because the names changed.)

https://www.americanradiohistory.com/Radio_Retailing_Magazine.htm

[Ritchie200]

Holy cow, the mother lode!  Yeah that was the one thing I didn't do (shorten the URL).  Wow there is a lot of material there!  I could easily get lost in there....   Thanks PRR!

Jim

[jjasilli]

Great - there are some good articles in the posted Issue which are part of a series.  I need to learn to use Excel to make an index of topics related to source material.

[shooter]

learn to use Excel

I got pretty good writing macros in excel for work, but here, I just cut/paste links in word, give each broad topic a bold larger font header. course the file keeps getting lost in the clutter 

[jjasilli]

I just found online tutorials to set up Excel for a spreadsheet of cooking recipes.  A simplified version of that should work.

[Tony Bones]

> the only copy/issue I could find.    Maybe someone can find some archived.

Shorten the URL and see what the home of the website is.

https://www.americanradiohistory.com

Ah-ha. Bunch of magazine scans.

TIP: go to the "A-Z" box and try "E" for Electronics Technician. (Sometimes you have to grope because the names changed.)

https://www.americanradiohistory.com/Radio_Retailing_Magazine.htm

When you get done there, read every issue of Wireless World. https://www.americanradiohistory.com/Wireless_World_Magazine.htm

Back before the internet I spent days sitting on a library floor reading WW. Some real gems hiding in there...

[shooter]

cut my teeth on this mag

https://www.americanradiohistory.com/Archive-Radio-Electronics/70s/1974/Radio-Electronics-1974-02.pdf
then Mad mag
then Byte
then FTP
then www
 

[Ed_Chambley]

Hold up on that carwash boys! Wireless World mag, who ever heard of such a thing.  Futuristic gibberish I say!  Just the let you know, I "ran across" another Simpson 260, v6, in the box with the leather carry case which was sold separate.  Both unused.  Had to pay $50 for them, new probes and all.


Now I finally have every everything I ever wanted!


Negative resistance is paddling against the water to keep the Kayak on the correct line, but still moving forward due to the whitewater.  Not really, but sounds cool!  And remember, 10 9 8 7 6 5 4 3 2 1 Zero, when you get down to Zero, you still got a whole lot more!

[shooter]

Simpson 260 Had to pay $50

imo one of the best meters of all time!
the gray matter says the Navy paid closer to $1200.  That's how I saved my stripes, bought a meter, Lots of probes and the BNC connectors we used to make bowls from    (one got dropped down 3 decks, banging off ladders n bulkheads and still worked! although I sent it back for cal, just in case)

I like the whitewater explanation, much prefer to measure in absolute values though if the engineers n math folk need a - sign, just footnote the data  * both + / - values shown for confusion sake 

[Tony Bones]

OK, so I decided to go back and read again some of those old issues of Wireless World to see if the magazine really was awesome or if I was just being nostalgic for th good old 1980's. I decided arbitrarily to start with January 1945. What I found was an article by L. Hartshorn called MECHANISM OF DIELECTRIC HEATING which was not exactly mesmerizing, but it is worth a read if you're curious about dielectric absorption and what it means in a physical sense. I mean, it's the single biggest contributor to making real capacitors non-ideal, so it's worth thinking about if you have the time.

The February 1945 issue contained nothing interesting except a letter to the Editor by Arthur C. Clark predicting the use of satellites in geosynchronous orbit for global communication.

The March 1945 issue contains an article by G. N. Patchett where he describes simple bass and treble controls. Really, he develops variable low- and high-pass filters, then leaves it up to the reader to combine them. He also claims to have discovered how to improve them by the addition of a mysterious signal that does not dependent on frequency. He promises to explain it later, but doesn't. Maybe in a later issue of WW? Worth a skim.

Also in the March issue is a seminal article by W. T. Cocking about bypassing or not a shared cathode resistor in PP stages. Here he provides an interesting analysis and shows that in the output transformer even order harmonics cancel and odds add, while in an unbypassed cathode resistor the evens add and the odds cancel. Cocking was a pretty good writer, so the article is comparatively easy to read, at least compared to the level of the subject. There are a few places where he gets tangled up trying to describe in words something ... difficult to describe in words. But you can usually just skip ahead to where he writes "in other words..." and start reading again from there.  Not for everyone, but some people might enjoy reading it.

[Ritchie200]

So... Are you convinced that they were really awesome? 

Jim

[Ritchie200]

Man, there is some great stuff there!  This is gonna take some time!

Jim