Friday, December 21, 2018

My Favorite Irrational Number

I have always been interested in numbers, especially special numbers like Pi (3.1415. . . ).

Normal whole numbers, like 1, 2, 3, etc (and their negative counter parts) are amazing when you consider there is no end to how far you can go to find a larger number, just by adding one. Within that very large range of numbers, there are many numbers which have their own special properties, for example the "Prime Numbers". As with all whole numbers, there is no Largest Prime Number, there is always a larger one to be found.

The whole numbers (plus/minus) and fractions that can be written using them are known a "Rational Numbers" - meaning that they can be written as a ratio (a fraction), for example:  1/1, 1/2, 1/3, etc.

But there is another class of numbers that can NOT be written as a ratio of two whole numbers, they are called "Irrational Numbers", for example the value of "Pi".  Pi can be written with many-many non-repeating digits without end, but Pi could never be written as an exact fraction (a ratio) of two whole numbers. There are many such "Irrational Numbers", many are used in science and found in Nature.

My favorite Irrational Number can be computed as simple as: (1+sqrt(5))/2

This can be computed with as many digits that you like with a simple Unix command (change that scale as desired for the number of digits):

        echo "scale=1000; (1+sqrt(5))/2" | bc

This is a very special number known as "phi".

A very interesting property of phi is:  1/phi = phi-1

No other number has this simple property.

Phi is found in many places in Nature, for example it is the way seeds are arranged withing a Sun Flower, the size of chambers of the Nautilus fish,  etc.

Phi is the name given to what is also called the "Golden Ratio" or "Golden Rectangle".

Here are the first 1000 digits of Phi:


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Wednesday, April 4, 2018

Hands Free Jig

Added Details and Links

In the past I successfully have used "Hands Free Soldering Jigs", but I wanted more functionality.

I found on ebay Machinist Magnetic Indicator Dial Gauge Holders, with a little 3D Printer Designed Adaptor they could be used as a Hands Free Soldering Jig.

A single Knob adjust and locks all three major joints.

In this case, the yellow alligator clip adapter was 3D Printed.

Also, another adapter (black) was printed, and a "Hat Pin" heated and inserted. This makes for a very nice PCB probe, an Oscilloscope probe can be attached to the top of the pin.

Once adjusted, these Dial Indicator Holders are "Rock Solid", once positioned they stay put, allowing for precise probing.  I use tape to hold board under test to the bench (thanks, Jeff - KO7M).

If used, the Magnet Base needs a stable steel attachment point, in my case, my bench edge is metal and provides as necessary.   The Magnet Base could be abandoned for something that could be attached to a wooden bench.

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Monday, April 2, 2018

Test Lead Rack - For my eShop

In my Electronics Shop, space and organization is always a challenge.  The following 3D Printed Test Lead Rack will help.

An Interactive Link To The Design

I designed the Test Lead Rack with Fusion 360 as one of my efforts to learn this new (to me) software.  I had been using Sketchup for most of my previous projects, but the lure of Parametric Design is to great to NOT switch to Fusion 360.  Also, a lot of public available designed parts are available from Fusion 360.

Now 6.5 hours later after design, the 3D Printer provides the Results:

And now, it is in use:

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Sunday, January 7, 2018

3D Printer - MY Noob Mistakes

As posted before, I have been playing with a new TEVO Little Monster 3D Printer, I have made a LOT of Noob mistakes that could have been avoided if I had only knew.

The following are notes to myself.

o. Do not turn off the power to the 3D Printer unless you are certain that the Hot-End has cooled down. if not, removing power to the 3D Printer will cause the filament to melt within the Cold-End and then a complicated repair method will be required to fix the problem.

o. Remember, 3D Printing is very SLOW, it is much slower than waiting for paint to dry.

o. Remember the hot-end is VERY HOT, I have several burns to remind me.

o. Learn how to set the Z zero Height to within a paper thickness of the print bed, or nothing will work correctly until you do, no mater how hard you try.

o. Buy several sets of Print Head replacement parts, for the; Cold-End, Thermal Break, and Hot-End.

o. Consider buying some Tetrahydrofuran (THF) , it is the only effective thing that will dissolve PLA (for Hot-End  clean and repair), and it can be used to glue PLA parts together. Or at least that is what google suggests.

o. Note, MOST often Hot-End repair work will be done while it is HOT (about 210 C, or more), other wise PLA will be hard and not easily removed.

o. For my use, Blue Painter Tape works best for the Printer Bed, it has some texture that will show up on the printed part, but PLA stick very good to it. A roles of Blue Painters Tape (10 inches wide) are available on-line for about $50, and worth every penny, it makes bed prep very easy.

o. If the Hot-End is disassembled, for cleaning or repair, remember it has to be re-assembled and tightened while at intended operating temperature, for me that is about 215C.  If not, it WILL leak.

Note: I will add to this list as I learn more.

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