Microohm Meter with LED Analog Bar

This indicates like LM3914 in dot-mode. It is a drawing i made made to troubleshoot a gadget, around two decades ago. Strangely it had a echo of a design i had made into a 7107 dpm years before that. Now i am scanning all my drawing and notes, useful or not. Clean or with errors. Many Errors = 1 Blunder. Some projects i made have been expensive Blunders. So see them with a skeptic eye, fix them, try them. Thats all for now.

See the Circuit Full Size – Microohm Meter with LED Analog Bar

This has a 9V battery power. The 555 spins and a negative voltage for Opamp is created. This is a Low Offset amp of OP37 of Precision Monolithics, Inc PMI an early innovator. This diff-amp amplifies the uV of a 4 wire resistance measurement.

Now the current pump is the 2N2222 you see above the OP37. The FET and 555 do synchronous rectification. The LM324 is the Indicator and Analog to LED Dot-Bar Converter. The probes are Gold Plated, or use solid gold pins if you have them in plenty.

  • Homo sapiens to Homo LudensHomo sapiens to Homo Ludens
    A long, long time ago a bright ape figured out that by climbing down from the trees he could more easily master his life, and [...]
  • Coprolite Homebrew Computer ConstructionCoprolite Homebrew Computer Construction
    The first microcontroller I became fascinated with was the 8048 (and 8748). This site has a lot of info on the 8048 and Z80, including [...]
  • RCA connector or Phono ConnectorRCA connector or Phono Connector
    An RCA connector, sometimes called a phono connector or cinch connector, is a type of electrical connector commonly used to carry audio and video signals. [...]
  • DiscoverCircuits free electronic circuit links
    DiscoverCircuits free electronic circuit links DiscoverCircuits, has 26,000 + electronic circuits or schematics cross-referenced into 500+ categories. As a vital resource for engineers, hobbyists, inventors [...]
  • Applied Magnetics by Barry Hansen
    Barry Hansen enthusiasm for Coilgun Designs has created an EE education portal. Applied Magnetics by Barry Hansen See the RLC Simulator and Inductor Simulator. By [...]
  • 3 axis stepper motor driver using a single RS-232 port
    Stepper motors translate digital switching sequences into motion. They are used in printers, automated machine tools, disk drives, and a variety of other applications requiring [...]
  • EE Video Blog EE – David L. Jones
    Off-the-cuff video blog and Podcast of interest to anyone involved in electronics design. Electronics professionals, hobbyists, hackers, and makers will find something of interest here. [...]
  • Tutorials for Electronics – Williamson Labs
    These are simple and easy for learning, it is oriented towards practical electronics. It has a rich experience of Glen, who has seen the real [...]
About delabs 456 Articles
delabs is a web-service for product design and development.

Be the first to comment

Leave a Reply