Test-Measurement

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FreePCB is a free, open-source PCB editor, released under the GNU General Public License. It was designed to be easy to learn and easy to use, yet capable of professional-quality work.

FreePCB – PCB editor

Some of its features are:

  • 1 to 8 copper layers
  • Board size up to 60 inches by 60 inches
  • Uses English or metric units (i.e. mils or mm) for most functions.
  • Footprint libraries courtesy of Ivex Design International Inc.
  • Footprint Wizard and Footprint Editor for creating or modifying footprints
  • Imports and exports PADS-PCB netlists
  • Exports extended Gerber files (RS274X) and Excellon drill files

Example – Logic Analyzer: This is an open-source logic analyzer called MiniLA contributed by Bob Grieb of the User Forum. The image on right is the Logic Analyzer PCB.

FreePCB - PCB editor

Some Features:

  • Up to 32 channels
  • 128 Kb of memory for each channel
  • Sampling rate up to 100 MHz (timebase in 1-2-5 sequence)
  • Input levels compatible with 3.3V and 5V logic
  • Selectable pretrigger/posttrigger buffer size in 8K step

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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

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.

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“Bluetooth Multimeter is an intelligent peripheral of android phones, specially designed for engineers. Not only can it easily collect data such as voltage, current and resistance etc., this multimeter can also communicate with phones via bluetooth. Thus, the data gathered will be displayed on your phones.”

Bluetooth Multimeter – Seeed Studio

Totally open source, including hardware, software & Android API. Learn how to create a Platform to connect smartphones with the real life.

Bluetooth Multimeter - Seeed Studio

The Bluetooth Multimeter is based on Atmega328 – Arduino Pro. It measures the voltage and resistance and current input from the headphone jack, and then sent these data via the Bluetooth frame.

Android UI for Bluetooth DMM

This Bluetooth Multimeter is a portable multimeter, a device that gathers the voltage, resistance and current. and then sent these data to other device via Bluetooth, so, we could display the data through other devices, such as Android, PC and so on.

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Zelscope is a Windows software that converts your PC into a dual-trace storage oscilloscope and spectrum analyzer. It uses your computer’s sound card as analog-to-digital converter, presenting a real-time waveform or spectrum of the signal – which can be music, speech, or output from an electronic circuit.

Zelscope Sound card oscilloscope

Zelscope features the interface of a traditional oscilloscope, with conventional gain, offset, timebase, and trigger controls. As a real-time spectrum analyzer, Zelscope can display the amplitude and phase components of the spectrum.

Zelscope Sound card oscilloscope

The typical input voltage should be about 1 volt AC at the line-in jack of the sound card, so a voltage divider or a buffer amplifier is highly recommended.

xoscope for Linux –  Similar Ptoject

Zelscope also allows for an easy measurement of short time intervals in mechanics experiments. Zelscope has proven useful in debugging music and sound processing software.