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General Vintage Technology Discussions For general discussions about vintage radio and other vintage electronics etc. |
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11th Mar 2019, 6:26 pm | #61 | |
Dekatron
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Re: The slide rule
Quote:
Craig |
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11th Mar 2019, 6:57 pm | #62 |
Dekatron
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Re: The slide rule
I was trained on a British Thornton slider in my first two years at grammar-school - along with five-figure logtables.
By the 'Upper-5th' form [for us who'd taken our O-levels a year or two early so were now doing the A-level syllabus a year or two early too] when we were doing serious physics and algebra/trig I'd persuaded my parents to buy me an H-P 65 calculator. My father claimed it against tax as a business-expense, having bought a few dozen similar calculators for his techies. |
11th Mar 2019, 7:02 pm | #63 |
Dekatron
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Re: The slide rule
All a slide rule reminds me of is Sam Cooke and Otis Redding....I'll get m'coat.
Lawrence. |
11th Mar 2019, 7:38 pm | #64 |
Dekatron
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Re: The slide rule
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11th Mar 2019, 9:21 pm | #65 |
Dekatron
Join Date: Aug 2016
Location: Colchester, Essex, UK.
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Re: The slide rule
On closer examination, judging by the vacant grooves in the edge,my car boot sale buy has a piece missing.. (The cursor?)
The care and adjustment instructions hark back to a time when things need not necessarily be thrown away at the first hint of trouble! Speaking of having a piece missing....I too sat my Maths O Level in 1986..then again in 1987. Twice. Oh well, a C is still a pass i suppose. Dave |
11th Mar 2019, 9:53 pm | #66 |
Nonode
Join Date: Dec 2012
Location: Kirk Michael, Isle of Man
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Re: The slide rule
I think I still have 4 or 5 slide rules, and if I get one out, I will still be able to use it.
At school, we learned to use logs, and a friend of the family gave me his book of 7 figure logs, which I still have now. It also had 7 figure "quarter squares" though without opening the book, I forget what they were used for. I think the book was originally intended for nautical use. When I stater work, we had a "muldivo" "wind on" machine similar to that shown earlier. I could really rattle stuff out on that, multiplications or divisions as well as simple additions and subtractions. We had a special slide rule made up by an earlier lab tech for doing water absorbtion, VDS and VFS (volumetric drying/firing shrinkage) for all the special brick testing we did. In my next job, I needed to learn to use a slide rule for particle size analysis (a 6" Unique) and I quickly learned to use the C1 scale, making many calcs much quicker than with just C and D scales. I decided to buy myself a 10" rule, and in a local "high end" stationers I found a real beauty. Aluminium, I seem to recall it was light yellow, but its cost was way too much for me, so I came away with a Blundell "Academy 302", in my hands now.A,B,C,C1,D, LL2, LL3, Sin, Tan, sin/tan(small angles) and of course the linear L scale. I never understood why that L scale was not an exact 10", allowing it to be used for measurements as well. I have another one somewhere with a tapered edge with measurement (inches) on it, though that was a 5", so not appropriate. Les. From around 1960 to 1980, a 5" rule was in my top pocket at all times. Used daily, often many times daily. Last edited by MotorBikeLes; 11th Mar 2019 at 9:56 pm. Reason: addendum |
11th Mar 2019, 9:57 pm | #67 |
Octode
Join Date: Feb 2009
Location: Bletchley, Buckinghamshire, UK.
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Re: The slide rule
I remember having one of those stylus operated things in the 60's. It added up pre-decimal currency and I seem to remember a "carry" was done by a kind of hooking motion with the stylus, at the end of the slot. Sadly long gone.
I still have the Thornton AA010 "Comprehensive" that I used at school, and also an Aristo 0968, as pictured earlier in this thread. The Aristo includes a ruler and a set of conversion tables stored in the case. Last edited by m0cemdave; 11th Mar 2019 at 10:03 pm. |
11th Mar 2019, 10:16 pm | #68 |
Tetrode
Join Date: Apr 2017
Location: Woodend, Victoria, Australia.
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Re: The slide rule
Where I worked in the early 70's one of the foremen had a cylindrical slide rule.
I recall it was about 8-10" long and looked like a small telescope. I'd never seen one of those before. A look on ebay suggests it may have been an Otis brand. |
11th Mar 2019, 10:21 pm | #69 |
Dekatron
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Re: The slide rule
This is the current collection, with some notes on dates (where possible) and condition (only of some; not complete yet)
They span the date range of 1901 to 1977 I've really stopped collecting, but know myself well enough to realise that this is a rabbit hole I could easily go down again.... Craig Last edited by Craig Sawyers; 11th Mar 2019 at 10:26 pm. |
11th Mar 2019, 10:39 pm | #70 | |
Dekatron
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Re: The slide rule
Quote:
The methodology of these effectively mirrored that of an abacus.
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Mending is better than Ending (cf Brave New World by Aldous Huxley) Last edited by Dave Moll; 11th Mar 2019 at 10:41 pm. Reason: comparison with abacus |
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11th Mar 2019, 11:28 pm | #71 | |
Octode
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Location: St Ives, Cambridgeshire, UK.
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Re: The slide rule
Quote:
Andrew
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Invisible airwaves crackle with life. Or they should do. BVWS Member |
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12th Mar 2019, 12:29 am | #72 |
Dekatron
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Re: The slide rule
Re #59, yes it was some time ago, in the late 1960's.
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12th Mar 2019, 9:47 am | #73 |
Nonode
Join Date: May 2007
Location: Preston, Lancashire, UK.
Posts: 2,511
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Re: The slide rule
Here's one in my collection, of interest to me because it has an Air Ministry Stores Reference Number, 6E-272. Section 6E is for 'Miscellaneous Instruments'.
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12th Mar 2019, 11:46 am | #74 |
Nonode
Join Date: Nov 2016
Location: Aberaeron, Ceredigion, Wales, UK.
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Re: The slide rule
I wonder if that one would have been allowed into the exam room, with formulas written on it?
Cheers John |
12th Mar 2019, 1:17 pm | #75 |
Dekatron
Join Date: Apr 2012
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Re: The slide rule
As well as slide-rules, I always liked the rotary drill/tap/thread-size calculator things, such as: https://collection.maas.museum/object/381798
There were some more-sophisticated versions for specific applications that had _two_ overlapping wheels on different axles, with helices of holes in each wheel that you lined-up to read the result off. I remember one such beastie being for gas pressure/temperature calculations and the different helices being for the different gases (hydrogen, oxygen, methane, ammonia etc). The numbers for the Ammonia calculations were printed in green! |
12th Mar 2019, 7:41 pm | #76 |
Dekatron
Join Date: Aug 2016
Location: Colchester, Essex, UK.
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Re: The slide rule
Andy's post #73- appears to be a 'Unique' slide rule similar, but not the same as mine. The centre piece is wider and where my scale goes up to 10 his goes up to 11!
No War Dept. stock number on the rear, it merely says -Copyright- Dave |
12th Mar 2019, 8:07 pm | #77 |
Triode
Join Date: Oct 2018
Location: South Lakeland, Cumbria, UK.
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Re: The slide rule
For MotorBikeLes:
Quarter Squares was a multiplication algorithm. To multiply two integers using a quarter squares table: 1) find the sum and difference values between your integers 2) look up the quarter square values in the table (whose value is floor[n^2/4] - hence the name quarter square) 3) take the difference of the quarter square values so for 5*7 1) sum and differences are 2 and 12 2) look up the quarter square values which are 1 and 36 respectively 3) take difference between the quarter square values is 36-1 = 35 = 5*7 Quarter Square (2) = floor[2^2/4] = 1 Quarter Square (12) = floor[12^2/4] = 36 Hope I've got that right - I believe that whilst some extensive tables were published, the quarter square algorithm found much more utility as a computer algorithm. Much as I loved my slide rule (down to my last 5); I wouldn't swap for my RPN calculator. Nick. |
12th Mar 2019, 10:45 pm | #78 | |
Nonode
Join Date: May 2007
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Re: The slide rule
Quote:
Andy |
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12th Mar 2019, 11:12 pm | #79 |
Octode
Join Date: Jan 2003
Location: Guildford, Surrey, UK.
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Re: The slide rule
I have this Produx German made mechanical calculator, similar in principle to the ones already posted and the instructions in German. It is operated by a stylus. The display digits are reset by pulling up a bar at the top of the calculator body. It belonged to my Dad but I never saw him use it.
I also have a British Thornton slide rule, used at college and somewhere a specially made CEGB slide rule for calculating telemeter settings. Telemeters were used to bring in data from transmission substations over telephone lines in CEGB days. Ron |
13th Mar 2019, 6:04 am | #80 | |
Dekatron
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Re: The slide rule
Quote:
It comes from that facts that (a+b)^2 = a^2 + 2ab + b^2 and (a-b)^2 = a^2 - 2ab + b^2 so (a+b)^2 - (a-b)^2 = 4ab I've seen it done in hardware using a ROM lookup table for the squares and a set of full adders to calculate sums and differences. Of course dividing by 4 is trivial in binary. The advantage over a lookup table for products is the reduction in size of the table. To do an 8bit * 8bit multiplier lookup table you need a table of 65536 entries. But since the sum of 2 8 bit numbers is 9 bits or less you only need a 512 entry table of squares. |
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