ANALYTICAL SCALE  M E T T L E R  INSTR. CORP., Hightstown, NJ / USA (1960)
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Mechanical Binary-Coded-Decimal Balance Scale, Max = 160 g ;  Acc. = .5 mg

HOW THE METTLER  » H15 «  LAB SCALE WORKS :
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For very low weights the known balance system doesn't work: The mechanical 
frictions are limitations. The METTLER  »H15«  use a DIFFERENTIAL METHODE:

With  NO PROBE in the bowl, the scale is in balance with a CONSTANT WEIGHT
of 159.9 GRAM and movable COUNTER-WEIGHT RINGS up to the SUM of 159.9 GRAM

The electric wire powers a light bulb. Its light ray projects the (moving)
NUMBER-SCALE on the MILKY-SCREEN in front.  A PROBE IN THE BOWL brings the
scale out of balance. 3 DIGITAL KNOBS (BLACK = 10s; BLUE = 1s; RED = 0.1s)
on front LIFT (!!!) the COUNTER-WEIGHTS in the way,  until the scale is in
balance again:  SUM  OF  L I F T E D  COUNTER WEIGHTS  =  PROBE's  WEIGHT. 


P R I N C I P L E :                                    (A) START Position:
                                                       *******************
      +===============+===============+    3 x 4 = 12 COUNTER WEIGHT-RINGS
      |              _V_              |         are laying on their  BASES
      |               ^               |             ( TOTAL = 159.9 GRAM )
      |                               |
      |              RED       o=o=o=o|o=o=o=o     ( .1 + .1 + .2 + .5 ) g
      |                        v-v-v-v+v-v-v-v
      |                               |
      |                               |
      |              BLUE      o=o=o=o|o=o=o=o     (  1 +  1 +  2 +  5 ) g
      |                        v-v-v-v+v-v-v-v
      |                               |
      |                               |
      |              BLACK     o=o=o=o|o=o=o=o     ( 10 + 20 + 40 + 80 ) g
      |                        v-v-v-v+v-v-v-v
      |                               |
      |         (B)  Dials ...        |          ...  L I F T   Rings  ...
 +----+----+    **********       +----+----+     *************************
 | 159.9g  |                     |         |       - .1 - .1 - .2
 +---------+                     |         |       -  1      -  2
    WEIGHT           PROBE   =   | 123.4 g |                 - 40 - 80
    INSIDE                       +=========+
                                      ^       ... SUM  =  - 123.4 g

                                              DISPLAY  =  | 12 | 3 |.| 4 |

      ... made now the left and right side in BALANCE  ~  ZERO  on  Screen
      ( MILLI GRAMS are to be read on the PROJECTED SCALE / MILKY-SCREEN )


      +===============+===============+                 (C) ZERO Position:
      |              _V_              |                 ******************
      |               ^               |
      |                          o=o=o|o=o=o
      |              RED       o======|======o     ( __   __   __ + .5 ) g
      |                        v-v-v-v+v-v-v-v
      |                               |
      |                          o===o|o===o
      |              BLUE      o===o==|==o===o     ( __ + 1    __ + 5  ) g
      |                        v-v-v-v+v-v-v-v
      |                               |
      |                        o=o====|====o=o
      |              BLACK     . . o=o|o=o . .     ( 10 + 20   __   __ ) g
      |                        v-v-v-v+v-v-v-v
      |                               |
      |                               |
 +----+----+                     +----+----+
 | 159.9 g |                     |         |
 +---------+                     |         |
    WEIGHT           PROBE   =   | 123.4 g |   +   WEIGHT-RINGS  =  36.5 g
    INSIDE                       +=========+
                                      ^              159.9 GRAM  =  TOTAL

               HAVE A LOOK INSIDE ...

R E M A R K S   T O   S E N S I T I V I T Y   O F   T H E   » H 15 «   ...
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2 Marks on the LETTER SCALE represent 1 GRAM [ 1 g ]; 2 Marks on METTLER's
»H15« PROJECTION / MILKY SCREEN shows 1 MILLI GRAM.  1 mg  =  1/1000 g (!)  

EXAMPLE:
--------
Set all DIGITS to ZERO; the projection screen shows ZERO MILLI GRAM = 0 mg
A WHISKER of our cat LEO, placed on the platform, shows a WEIGHT of 3.5 mg

H I S T O R I C A L   R E M A R K S :
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based on:    http://us.mt.com/us/en/home/site_content/aboutus/history.html

In 1945,  Erhard Mettler,  a Swiss engineer, started a precision mechanics
company in Kuesnacht, Switzerland.  He invented the substitution principle
with a single-pan balance, capable of being produced in series. Analytical
balances with  single weighing pan gradually replaced conventional two-pan
balances in the laboratory  and  »METTLER«  became the  synonyme for high-
precision scales. In 1980 he sold his business to the CIBA-GEIGY AG and in
1989  METTLER acquired  TOLEDO SCALE CORP., the largest US manufacturer of
industrial and retail scales  based in Columbus, Ohio.  Its founder, Henry
Theobald, had launched an innovative store scale  with an automatic weight
& price display in 1901.  The fusion »METTLER-TOLEDO« was a rational step.

impressum:
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© C.HAMANN          http://public.BHT-Berlin.de/hamann            08/22/11