The Big Slide Thread

[kvom]

I used slide rules all through university in the late '60s. I had a bad habit of losing them periodically, which became expensive. I created a geocache years later that required knowledge of a slide rule and logarithms to calculate the GPS coords:

https://www.geocaching.com/geocache/GCRFRB

 

[Gordon]

I used a slide rule frequently in one of my first jobs. It was a sales office where we purchase the parts and subcontracted fabrication of special equipment that we, the engineering department designed. At the end of the job we had to recap the job to determine how much the engineering department had earned or lost on each job. That involved calculating a 15% markup on all purchased parts and labor. That was done by dividing the cost by 85 which was done with a slide rule. The accounting department was always trying to transfer engineering department funds to other department. This was in the days before everyone had a calculator. The only calculator was a mechanical Monroe on the accounts desk thus the slide rule calculations. We usually came out within 1% of the accounting department because the estimates on the precision of the slide rule were as often high as they were low so in the end it came pretty close.

On a side note: There was always an uneasy relationship between the accountant and the engineering department. Periodically when he went to the restroom someone would go up to his desk and divide some number by zero and the that would cause an endless loop and the mechanical calculator would just keep clunking away until someone stopped it or the bearings gave out.

 

[stanstocker]

I had to look that one up.
Found a picture below.

And they forced us to use a Smith Chart in the field theory class.
I must confess, I never got the feel for using a Smith chart.
I understood that it was a tool used to solve fields problems, but it also has sort of a corn maize feel to it too.
I have seen others use a Smith chart, such as my profesor, and so I know it works.
The first thing that came to mind when I saw a Smith chart was "what the flock are they trying to make use do now?".
Sort of like Chinese water torture; the things they use to force us to use.

.

It had been many years since plotting my last Smith Chart. Recently I bought one of the two port 3 GHz VNA gizmos that are now less than $200 USD for playing with some antenna and feedline designs, an old interest that I have time to fool around with now. It's quite interesting how useful a Smith chart is when a gadget plots it for you, all the impedance vectors plotted in seconds with that lovely 50 ohm point dead center.

Hopefully re-learning some of this stuff and keeping on learning new things will help keep the aging brain from turning to mush.

As asked in the fine film Airplane, "What's the vector Victor?

 

[L98fiero]

Ironically, this is sort of what I consider the "slide rule" of lathes; ie: it is old, manually operated, clunky compared with modern CNC machines, but a very capable machine in the hands of someone who knows how to use it.
The new guys would say "Where is the keyboard ?".
.

The first shop I worked in had a number of lathes like that with added on electric motors and a four speed transmission, one of them had a 6 foot swing spindle and a 2 foot swing on the same lathe. The story was that the shop had a foundry at one point and when the city streetcar barns burned, they were given that lathe that was used to recondition the wheels as scrap, they got a job that requires a large swing so the bronze bearings were replaced and it was put back into use. It wasn't used often but it was the only lathe that size anywhere close.

 

[a41capt]

It had been many years since plotting my last Smith Chart. Recently I bought one of the two port 3 GHz VNA gizmos that are now less than $200 USD for playing with some antenna and feedline designs, an old interest that I have time to fool around with now. It's quite interesting how useful a Smith chart is when a gadget plots it for you, all the impedance vectors plotted in seconds with that lovely 50 ohm point dead center.

Hopefully re-learning some of this stuff and keeping on learning new things will help keep the aging brain from turning to mush.

As asked in the fine film Airplane, "What's the vector Victor?

I purchased a NanoVNA for my antenna experiments, and can’t believe how powerful something that small can be, and all for $50 American!

John W