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  1. #391
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    Feb 2016
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    Quote Originally Posted by Mr Brush View Post
    I still use my trusty HP32S RPN Scientific which got me through uni some 35 years ago.

    We poor students could only lust after HP41C/CV, but thanks to the wonders of technology I now also use a 41C app on mobile phone.

    Having grown up with RPN, it's very difficult to use anything else !
    You blokes amaze me. I had mine for years.

    It only left me in tears and very sad. Damned thing boggled my mind

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  3. #392
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    Feb 2006
    Location
    Perth
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    27,794

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    Quote Originally Posted by woodPixel View Post
    You blokes amaze me. I had mine for years.

    It only left me in tears and very sad. Damned thing boggled my mind
    I found once I had worked out what a "stack" was and how it operated it was quite easy.

  4. #393
    Join Date
    Nov 2005
    Location
    Darkest NSW
    Posts
    3,207

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    Yup, to we RPNites, "brackets" is a dirty word . Stack trumps brackets every time.

    Must admit it was fun when someone borrowed my HP calculator......just to watch them scratching their head for a while before they asked "Where's the equals key?"

  5. #394
    Join Date
    Oct 2015
    Location
    Ringwood, VIC
    Posts
    580

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    The hp45 was the go when i was a student.
    Being a poor student, i made do with a clone, the corvus 500.
    I stumbled across it the other day. I ought to see if it will fire up... (or perhaps smoke up..

  6. #395
    Join Date
    Feb 2016
    Location
    Canberra
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    Hows $1.50 for a Kg of Hydrogen!

    New doodad is 95% efficient.

    This will do quite nicely for storage of Wind/Solar and remotes.... NICE!

    Record-breaking hydrogen electrolyzer claims 95% efficiency

  7. #396
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    Jun 2009
    Location
    Elizabeth Bay / Oberon NSW
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    76
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    934

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    Quote Originally Posted by woodPixel View Post
    Hows $1.50 for a Kg of Hydrogen!

    New doodad is 95% efficient.

    This will do quite nicely for storage of Wind/Solar and remotes.... NICE!

    Record-breaking hydrogen electrolyzer claims 95% efficiency
    I imagine hydrogen will form part of the future energy mix as a storage system and it's great that they've managed to reduce the price. However, there are number of issues I now see with hydrogen. Firstly, at ambient pressure it only has 11 MJ/m3 whereas petrol stores about 36,800 MJ/m3. So it requires compression which requires energy and creates heat which is probably lost in process. Storage costs and transportation are also very high. Batteries are about 90% efficient whereas hydrogen is about 41% using fuel cells and 35% using combustion. That's a huge waste of green power when it could be used elsewhere. I cite Saul Griffith's book The Big Switch as my data source.

    Griffith's overall message is electrify everything which uses energy. He posits that wind and solar convert natural energy directly into electrical energy whereas every other system converts its inherent potential through other forms of energy before generating electricity, and each time it converts, efficiency suffers. The beauty about wind and solar is that it is easily and inexpensively established versus the minefield of approvals needed for either fossil or nuclear fueled facilities; to say nothing of their capital cost and lead time.

    mick

  8. #397
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    Feb 2016
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    Quote Originally Posted by Glider View Post
    The beauty about wind and solar is that it is easily and inexpensively established versus the minefield of approvals needed for either fossil or nuclear fueled facilities; to say nothing of their capital cost and lead time.
    This is most interesting.

    I saw a video where the maker said exactly this.

    The Interviewed was asked why the USA was putting in such an astronomical quantity of solar. He cited the fact the approval was a local bumpkin council (easy - literally anyone can install it en mass, starting Next Tuesday) whereas a nuke plant was a regulatory hell (cost, specialists, regulation, 10 year builds, specific places, etc, etc, etc)

  9. #398
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    Quote Originally Posted by Glider View Post
    That's a huge waste of green power when it could be used elsewhere. I cite Saul Griffith's book The Big Switch as my data source.
    Just bought Thanks for pointing it out.

    The Big Switch by Saul Griffith | Black Inc.

  10. #399
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    Feb 2016
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    Canberra
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    Default Self Driving Trucks and electrification

    This is a small adjunct to the electrification-of-everything.

    Robot Truckers Could Replace 500K U.S. Jobs

    and

    Can a Self-Driving 40-Ton Truck Be Safe? Developers Say Yes - Bloomberg

    Imagine having the truck simply as a big battery and motors, with a supplemental battery in the bogie. These things can putter back and forth, perfectly safe, on long haul deliveries.

    Obviously not for the Nasty Parts (crappy roads, inner city to outer depot), but obviously very suitable to big chunks of Australia.

  11. #400
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    Jun 2009
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    Quote Originally Posted by woodPixel View Post
    Imagine having the truck simply as a big battery and motors, with a supplemental battery in the bogie. These things can putter back and forth, perfectly safe, on long haul deliveries.

    Obviously not for the Nasty Parts (crappy roads, inner city to outer depot), but obviously very suitable to big chunks of Australia.
    It might prompt a man to go into the truck hijacking game.

    mick

  12. #401
    Join Date
    Nov 2004
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    Millmerran,QLD
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    73
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    11,136

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    Quote Originally Posted by AlexS View Post
    Apologies for thread drift...

    BobL, thanks for that diagram. Back in the early '60s I bought a set of log tables (remember them) which had, inside the covers, the definitions of many physical quantities in terms of other, basic, physical quantities. I referred to them so often that eventually I learned them, and even, sometimes, understood. However, when I had to use seven digit logs, I somehow lost those tables.
    Doesn't matter now, i guess, if so many of them have been re-defined.

    OK, you may now resume normal service.
    Alex

    Bit like this perhaps except we called them "Four Figure Tables" and you can see why from the cover. Mine date from 1965.

    P1080167 (2).JPGP1080168 (2).JPGP1080169.jpg

    I have been away from home for a couple of weeks so had no access to ancient hoarded treasures. I only ever used these in exams. Calculators were not allowed.

    Regards
    Paul
    Bushmiller;

    "Power tends to corrupt. Absolute power corrupts, absolutely!"

  13. #402
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    Canberra
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    This will be very nerdy, but when I can't sleep I do square roots in my head to four digits.

    I'm unwell

  14. #403
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    Jun 2007
    Location
    Blue Mountains
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    817

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    Square root of 2 = 1.4142135, 3= 1.7320508

    WP, I think we share some common traits.

    ajw

  15. #404
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    Its not hard to work out on paper, but the trick is keeping the totals in working memory. It can be quite challenging.

    I often fall asleep 😂😸, or if I can't clear my mind this works wonders. Its akin to a meditation.

  16. #405
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    Jun 1999
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    Westleigh, Sydney
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    Quote Originally Posted by Bushmiller View Post
    Alex

    Bit like this perhaps except we called them "Four Figure Tables" and you can see why from the cover. Mine date from 1965.

    P1080167 (2).JPGP1080168 (2).JPGP1080169.jpg

    I have been away from home for a couple of weeks so had no access to ancient hoarded treasures. I only ever used these in exams. Calculators were not allowed.

    Regards
    Paul
    They're the same ones I had at school. Must have been the standard issue. Later, at tech, I bought a set that had all the physics info inside the covers.
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