Online source for slide rules & surplus electronics?

Hi all
I'm looking for an reliable online source for slide rules in the US. Note that I don't need antiques nor collectables, but a slide I can learn with
and use daily in the shop. Also wanting to buy large surplus diodes (for future DC welder construction). Someone posted an url (a dependable supplier?) but I cant remember it.
Any help thanked in advance.
--

Regards,


Mongke
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wrote:
||Hi all || || I'm looking for an reliable online source for slide rules in the US. Note ||that I don't need antiques nor collectables, but a slide I can learn with ||and use daily in the shop. || Also wanting to buy large surplus diodes (for future DC welder ||construction). Someone posted an url (a dependable supplier?) but I cant ||remember it. ||
Coworker bought this one http://www.stupid.com/stat/SLID.html
A very nice rule. Probably pretty expensive when new. Still new, $6.99 Texas Parts Guy
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MECI has 150 and 300 amp diodes and I've had good luck with them in the past:
http://www.meci.com
I've also bought suplus electronics from Marlin P. Jones & Associates at:
http://www.mpja.com
I don't know of a slide rule supplier but I'd start with eBay. And there's always this one:
http://www.taswegian.com/SRTP/javaslide/javaslide.html
:-)
Best Regards, Keith Marshall snipped-for-privacy@progressivelogic.com
"Even if you are on the right track, you'll get run over if you just sit there." - Will Rogers (1879-1935).

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On Tue, 20 Jul 2004 20:19:40 +0000, Keith Marshall wrote:

Thanks I'll give them a try.

Hmmm. Tough thing dragging the 'puter down to the shop and have it perform amidst sparks and chunks of flying metal ;-)

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Mongke
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I have a few used 300 amp diodes left, see the electronic parts for sale page on my web site, www.home.labridge.com/~wnoble
maybe these will do your trick - I can ship a bunch in a flat rate envelope to keep postage down.

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Hit the garage sales, that's where I've picked up the ones I have. (About twenty of them now, still looking for something besides aluminum Picketts.) Cost me about a buck each, and that includes some I don't even pretend to know what all the scales are for. Also includes a 20" K&E.
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    You don't *want* collectibles, but I don't think that anybody still makes the things, so any you find *will* be a collectible, and you'll have to look in such a place.
    These days, you would do best to go to yard sales, antique dealers, and eBay to find them. I got my first ones from Sears (rather poor ones, but enough to learn on, and I was a kid then.
    Later, I got a pocket sized (5") all metal one from Pickett -- bought from a local office supplies store.
    My first *good* 10" one was from Lafayette Radio (now long out of business). That was around 1960 -- and the quality of the slide rule was excellent, though most Japanese tools and equipment was rather poor quality at that time.
    After that, I picked up several used K&E ones (including one barely used from a summer hire who changed to business after a summer of actually *working*. :-)
    My best two are a 20" K&E, and a Russian circular slide rule in a pocket-watch case. (The K&E is the more accurate, of course -- but the Russian one is fun.)
    Now -- if you are planning to use this in the shop, I should perhaps point out some limitations:
1)    A slide rule can't add. It multiplies, divides, squares and     square roots, logs, trig functions, and exponentials, but not     any good for adding.
2)    A slide rule is of limited accuracy. For the most part, you     should not expect to get more than three significant figures     out of it -- though this varies somewhat with where on the scale     you wind up, as things are spread way out at the low end of the     scale, and scrunched up at the high end. If you are working in     inches, say 1.25", you won't be able to calculate anything to     0.001" (where you are machining).
    If you want more significant figures, you need a longer scale.     20" is not enough for machine shop work. Big circular slide     rules squeeze a bit more scale length in a given maximum     dimension, but still is not adequate. A big cylindrical slide     rule might work -- but it would be awkward to use.
3)    *You* have to keep track of where the decimal point goes. Now     this is very good practice for a sanity check on the results of     an electronic calculator, but can really trip you up until you     are used to it.
    Frankly, for shop use, I would consider an abacus or a soroban (the Japanese version, with significant differences) to be more useful, as you can put the decimal where you want it, and keep several significant figures of accuracy. (Think of the slide rule as an analog calculator, and the abacus or soroban as a digital one.
    The slide rule was *great* in circuit design, as the components were usually not made to a precision as great as the slipstick could deliver. I would never consider it to be the best choice for machining.
    And these days -- *I*, at least, need my glasses and good light to read one. :-)
    Also -- in today's world, I would suggest a good scientific pocket calculator -- kept in a Ziploc baggie to keep swarf and coolant out of the thing, but to allow you to see and use the buttons and the display through the clear back of the baggie.

    I'm afraid that I don't remember it either.
    Good luck,         DoN.
P.S.    I also almost got arrested because of one. I was wearing it on     my belt, and a policeman thought that it was a knife. :-)
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On Wed, 21 Jul 2004 00:51:53 +0000, DoN. Nichols wrote:

Bummer. BTW, I seem to remember reading somewhere that at chip level (digital computers) division & multiplication are easy to implement, contrary to addition & substraction.

>     The slide rule was *great* in circuit design, as the components

Mmm. Had no idea. What they did use in the machine shops of old?

LOL. I keep a Leatherman Wave and a Maglite in my belt. I often get the suspicious look from security people
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Mongke
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    Hmm ... addition is quite easy at the chip level. For each bit, there are two duplicate interconnected circuits called "half-adders" (which can also be used for other things by themselves). Subtraction involves inverting all the bits of the subtrahend, and *adding* it to the other (with perhaps some fiddling to deal with the carry bit). Again, pretty simple to do in hardware.
    The software implementation of multiply involves a lot of shifts and adds, and needs an accumulator twice the width of the two operands.
    Hardware multipliers were available, (from people like TRW), but they tended to be big and hot chips (for their day). A 16x16 multiply chip was mounted in a 64-pin package -- the same size as the entire Motorola 68000 CPU.

    [ ... ]

    I suspect that pencil and paper was used mostly in machine shops in the US.
    As suggested before, an abacus (or equivalent) would be likely in oriental countries.
    There were some excellent mechanical calculators, such as the one by Frieden, but they were very expensive, and probably all of the gears in them did not deal well with the swarf to be found in machine shops, so if they had one, it would be in the office -- and a machinist would be more likely to use pencil and paper than to make a trip to the office. ;-)
    Enjoy,         DoN.
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On Wed, 21 Jul 2004 16:38:43 +0000, DoN. Nichols wrote:

You're right. I remembered it wrong. Thus, division is implemented as a series of substractions.
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    [ ... ]

    Subtractions and shifts to align the bits, so it doesn't take too many subtractions. (You *could* do it by simply subtracting the one from the other, and counting how many times it takes before the result goes negative -- then add one back and return the rest as a remainder.
    Enjoy,         DoN.
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Although, at it's heart, it *is* an analog computer that does add and subtract. The trick is, the scales convert the operands into logarithms - so the addition and subtration thus performed turns into multiplying and dividing, etc.
Jim
================================================= please reply to: JRR(zero) at yktvmv (dot) vnet (dot) ibm (dot) com ================================================
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This is a multi-part message in MIME format. --------------090602000207060209040806 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit
jim rozen wrote:

If you want a slide rule to just be able to add, just use two metric rulers side by side to do that.
Bill K7NOM
--------------090602000207060209040806 Content-Type: text/html; charset=us-ascii Content-Transfer-Encoding: 7bit
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html> <head> <meta http-equiv="Content-Type" content="text/html;charset=ISO-8859-1"> <title></title> </head> <body text="#000000" bgcolor="#ffffff"> jim rozen wrote:<br>
<pre wrap="">In article <a class="moz-txt-link-rfc2396E" href="mailto:cdksp9$pl7$ snipped-for-privacy@fuego.d-and-d.com">&lt;cdksp9$pl7$ snipped-for-privacy@fuego.d-and-d.com&gt;</a>, DoN. Nichols says...
</pre> <blockquote type="cite"> <pre wrap="">1)    A slide rule can't add. It multiplies, divides, squares and     square roots, logs, trig functions, and exponentials, but not     any good for adding. </pre> </blockquote> <pre wrap=""><!----> Although, at it's heart, it *is* an analog computer that does add and subtract. The trick is, the scales convert the operands into logarithms - so the addition and subtration thus performed turns into multiplying and dividing, etc.
Jim
================================================= please reply to: JRR(zero) at yktvmv (dot) vnet (dot) ibm (dot) com ================================================ </pre> </blockquote> If you want a slide rule to just be able to add, just use two metric rulers side by side<br> to do that.<br> <br> Bill K7NOM<br> </body> </html>
--------------090602000207060209040806--
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