The slide ruler!

[jacomart]

This afternoon, rummaging in a desk drawer, I found this and I was moved ... how long!  Do any of you still remember how to use it without reading the instructions?  Not me!  Nothing, I just wanted to share this emotion with you.

Cheers
JM

 

[user 37518]

Before my time! however, I love that scene from the movie Apollo 13 when Tom Hanks asks NASA to check his calculations and all the engineers take out their slide rulers to do the math.

Being an engineer is much easier today with our calculators, computers, simulators, the internet, etc...

The other day I was teaching my students how to use an analog VOM, and they were shocked by the complexity to use one, specially all the scales, the calibration procedure to measure resistance, using that little "mirror" strip so you avoid parallax error, the fact that they have a variable and relatively low input impedance measured in kOhm/volt, etc.

We take everything for granted these days. I saw a video on youtube that kids these days do not know how to open a can with a can opener, they don't know how to open or close a car window if its not electric, etc.... I'm not saying its good or bad, its just a sign of the days, a sign that we are getting older....

I'll tell you something which I do find terrible, kids these days do not want to remember anything, they do not want to commit anything to memory, they rely on their phone 100%, I know by heart a lot of constants like the Boltzman constant, electron charge, vacuum permitivity and permeability, also a lot of formulas, and they are impressed that I remember those, well more than impressed they are like why do you bother?And I always answer that in order to be an engineer you have to remember stuff, it makes other people more confident, it will impress your employer, imagine a doctor that asks Siri for your sympthoms, it doesn't look good doesn't it?

 

[ruffrecords]

I still have the one I got for my first year at university  back in 1970 and yes I can still use it but I much prefer to use a calculator.

Cheers

Ian

 

[JohnRoberts]

This afternoon, rummaging in a desk drawer, I found this and I was moved ... how long!  Do any of you still remember how to use it without reading the instructions?  Not me!  Nothing, I just wanted to share this emotion with you.

Cheers
JM

I still have my 12" plastic  Pickett microline 140 "slip stick" that I was issued at my second technician job back in the 70s. That was how we designed filters back in the day. Using a slide rule for such calculations imposed a mental discipline where you had to keep track of the decimal point and multiplier in your head, the slide rule only gives you the most significant digits. You have to decide whether that filter needs a 0.12 uF cap or 1.2 uf, or 0.012 uf. Generally we knew ballpark what size cap we needed just not the specific significant digits.

Mine has a bunch of scales I didn't know how to use back then, but has some nice "folded" scales that your's doesn't. The folded scales saves the time wasted resetting the cursor to reach a value hanging off the end.

Slide rule technology is old school... but before them, engineers were expected to use log look up tables from engineering manuals. Looking up the two log values and adding them together is not as slick as moving two log scaled rules along side each other to perform the addition (in log domain math, adding two log values together is equivalent to multiplying the root numbers together).   

JR

PS; For TMI as a young puke I recall getting a toy Abacus one Christmas.... Presumably it worked but I never became proficient. 

 

[fazer]

I started in 1970 with one as a chemistry major.  Used it for a year and a half before changing to a handheld scientific calculator.  Still have mine somewhere .  It belonged to my older brother who was 10 years older.  He became an accountant and didn’t need it any more.  They worked.  Just like a VU meter log scale.

 

[jacomart]

Slide rule technology is old school... but before them, engineers were expected to use log look up tables from engineering manuals. Looking up the two log values and adding them together is not as slick as moving two log scaled rules along side each other to perform the addition (in log domain math, adding two log values together is equivalent to multiplying the root numbers together).   

JR

PS; For TMI as a young puke I recall getting a toy Abacus one Christmas.... Presumably it worked but I never became proficient.

I got it!  Straight from my first year in high school! 8)

Cheers
JM

 

[crazydoc]

Yeah, those were the days - slide rules to 3 significant digits, and log and trig tables to 5 or 6. I still have my Handbook of Chemistry and Physics (Chemical Rubber Company), and back in the 70's I started collecting slide rules, knowing they would soon be useless and extinct. I have a whole box of them, but not any of the good ones except one K&E.