Test-Measurement (Page 2)

To make an analog design using log amps or multipliers, discovercircuits – four-quad is good for learning. Using a uP for math is better. Look at these links below. Build a Power Meter ! The Metrics for Going Green is with a Energy/Power/Watt meter.

enerjar - diy power meter

Related Reading

These are Instruments that Jack built. Here read Jack as me, delabs. Some were hand made, some in the form of workflow of a small firm with professional equipment. Some made in quantities, other a couple or more for R&D.

Test & Measurement Instruments delabs

Test Measurement Instruments by delabs

Test and Measurement is all about Measurement or Metrics. Without this, every other part of electronics becomes like boneless entities.

Instruments i designed and built. (long ago).

The usefulness of an oscilloscope is not limited to the world of electronics. With the proper transducer, an oscilloscope can measure all kinds of phenomena.

Type 465 Tektronix oscilloscope

Type 465 Tektronix oscilloscope. This was a popular analog oscilloscope, portable, and is a representative example. – XYZs of Oscilloscopes – Tektronix

Introduction to Oscilloscope – The single most important diagnostic tool used by experimental physicists is the oscilloscope. Certainly all scientists and engineers should be familiar with this common instrument, shown in the Fig. 1. An oscilloscope (scope for short) can be used to “see” an electrical signal by displaying a replica of a voltage signal as a function of time.

Introduction to Oscilloscope
Oscilloscope – Wikipedia

Oscilloscopes are used to observe the change of an electrical signal over time, such that voltage and time describe a shape which is continuously graphed against a calibrated scale. The observed waveform can be analyzed for such properties as amplitude, frequency, rise time, time interval, distortion and others.

Tektronix Reference Materials

There are many older Tektronix instruments that, with a little care and restoration, are just as useful as the latest and greatest. Knowing what you have or need, and how to use it, are often more important than having the “very latest”.

Oscilloscope at Willamson Labs

As important as knowing what is going on inside, is knowing how to make effective measurements using an integral part of the oscilloscope: the Scope Probes. The probe and how it is used, can make or break the usefulness of the oscilloscope.

Basic Function of an Oscilloscope

Interactive Demo – The oscilloscope is an electronic instrument widely used in making electrical measurements. The main component of the oscilloscope is the cathode ray tube (CRT). The CRT is a vacuum tube in which electrons are accelerated and deflected under the influence of electric field.

“From a small garage in Palo Alto, California, to employees around the world serving customers in 110 countries, Agilent has a long history of innovation and leadership in the communications, electronics, semiconductor, test and measurement, life sciences and chemical analysis industries.”

The company founded by William “Bill” Redington Hewlett and Dave Packard was know as Hewlett-Packard Company or HP. This was a Test and Measurement company. First popular product was a precision audio oscillator, the Model HP200A.

Later Computer and Printer products divisions retained the brand and firm and Agilent was spun off for for the Test and Measurement and other non-computer product line.

Agilent – Test and Measurement

34405A Digital Multimeter, 5½ digit

“The 34405A comes with a broad range of measurement functions, including temperature and capacitance measurements. The 34405A features simultaneous reading of DC and AC measurements with its dual display and can take up to 19 readings/sec at 4½ digit resolution through the standard USB interface.”

Agilent Educator’s Corner

On this web site, you’ll find electrical engineering insight, pre-written and interactive experiments, lecture assistance, reference materials, lab exercises, teaching tools, engineering student resources, and various research materials.

This was a Student Project of mine, it is a very basic instruments that could do most of the tasks on a test bench.

The cabinet used, was available as a part of a Hi-Fi DIY System, The Range and Mode switches were Modular Stackable Interlocked MultiPole Switches. The rest of the Interface were wirewound pots, jacks, sockets and plugs. The front panel was Engraved Acrylic, the panel was the toughest issue we tackled.

I wanted it to look well engineered, at least on the outside. It was a total analog instrument except for the digital indication of ICL7107. Thanks to ‘Intersil Hot Ideas’ Applications Book.

The above belong to an instrument Measureall shown below.

MeasureAll Benchtop Instrument

This is a Milli-Volt and Milli-Amp Source for Calibration of Temperature Measurement and Control Instruments using Thermocouples. There is also a Passive Variable Resistance Source for Simulating a PT-100 RTD Sensor.

Current Source mA for calibration

Temperature Calibrator

This calibrator was a simple solution i built. This instrument itself was calibrated by Instruments like the Calibrators from Omega which are the best you can get.

Instruments used in Calibration

Here are some Test and measurement notes. These ideas come from practical experience. But the jots are not in any order but are quite important.

Instrumentation and Automation

Scope Notes

  • If the waveform on the scope droops then you may need to use a 10X attenuating probe or mode. this attenuator is at the tip of the probe hence better measurement possible, also very high frequency signals may be best transmitted over a 50 ohm impedance matched line to the Oscilloscope.
  • Karl Ferdinand Braun – In 1897 he built the first cathode-ray tube…oscilloscope. CRT technology is to this day used by most television sets and computer monitors. The CRT is still called the “Braun tube”.
  • Do not use an oscilloscope to measure 230V directly, use a transformer, differential probe or attenuator.
  • An oscilloscope 1M probe or a DMM 10M impedance can load circuits with nano-pico amps of bias.

DMM Notes

  • Test a NPN transistor, DMM in 200K range. emitter negative probe, collector positive probe, it should show open. while still holding that way press wet finger on base and collector, it may show some reading, then it is ok. for PNP swap probes polarity and do the same thing. the wet finger when pressed applies a base current in uA.
  • The most common reason of DMM failure is when a person tries to measure 230V AC with a DMM in current or ohms mode, with the probes in the wrong sockets. Use external attenuators and shunts.
  • A DMM in diode mode or resistance mode can be used to test IR diodes, take it under 100W lamp and measure, cover the IR diode and measure you will see a response in proper polarity.
  • If you put the DMM in 2V mode and measure the voltage across a ordinary LED near a 40W lamp you will see around 200mV. Turn off 40W lamp the mV will fall near 0. Even metal-can transistors with their top ground away will become photo sensors.
  • When you measure low voltages or high resistance like 1M with a DMM your body must not be in contact with the probe tips. Body resistance is low in comparison so error in reading or loading of mV from sensor, in sensitive and high impedance ranges.
  • Red socket and probe for positive and black socket and probe for negative
  • Is it oscillating ?…. We cannot say, it could also be DC, you need to see if a Clock is present. use a signal tracer or a DMM freq mode, or AC measurement. or build this solorb.com-elect-logprobe. When you do not have a scope you can build one for the PC.
  • Polarity and Zero Cross indicators tell you to swap the leads. Use a comparator or opamp to build it.