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IBM History

Mystery Tool

The following photos show a measuring device that may or may not be IBM, and may or not be a CE tool. Here are some facts:

  1. The box has two handwritten numbers - 206256 & 2062564
  2. The meter face shows a logo "BL" and a number 3547860
  3. The thing that looks like a motor may well be a very sensitive meter movement instead. Applying a voltage to it made the needle move, direction dependent on polarity.
  4. The movement appears to equate to about 100mV to deflect to FSD
  5. Scale is marked in %, so appears to measure a deviation of + or – 100mV as a percentage of something
  6. At FSD the needle makes contact with the end stop, completing a circuit. The end stops appear to be adjustable.

Pin-out, International Octal base:

    • 1 = meter needle  (stop common)
    • 2 = meter
    • 4 = + stop
    • 5 = - stop
    • 7 = meter



    Click to enlarge photos.