Category Archives: Equipment

Chickens and the Unbroken Chain of Calibration

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A recent discussion in the LinkedIn group, Metrology & Test Measurement, on the “unbroken chain of calibration” has driven me to hone in on my personal understanding of measurement uncertainty. I am ashamed to say that I know virtually nothing (0 ±0.0031415929) about calibration despite having worked as an electronics technician in the ’90’s. My excuse is that ISO 9xxx only hit the repair floor in the ’90’s. (Well, that’s why it was called ISO 9000.)  But the National Bureau of Standards (NBS), which predates the National Institute of Standards and Technology (N.I.S.T.) by 87 years, has been around since 1901.

logo of National Institute of Standards and Te...

Logo of National Institute of Standards and Technology (Photo credit: Wikipedia)

And the NBS was predated by the International Bureau of Weight and Measures (BIPM in French). In any case, I’m not quite sure how to connect ISO 9xxx with calibration. It must come into it somewhere. All I remember was what kind of shoes to wear and grounding rules. I guess you could say that my uncertainty around these topics is not measurable or traceable!

How do we arrive at an unbroken chain when it comes to metrology? Let’s go to the start of the chain. We will use N.I.S.T. for discussion purposes but really it applies to any of the international organizations that set standards for metrology.

  1. We start with a reference point. This is a universally known measurement value of a particular measurable event. For example, the melting point of ice. (N.I.S.T uses a thermometer as an example on their website.)
  2. This reference is used as a standard by N.I.S.T. I assume that means that a correctly calibrated thermometer will measure – well, I’m not sure exactly what it will measure. It is close to 0 degrees Centigrade. There are various factors that can determine the temperature, such as atmospheric pressure and the purity of the actual water that the ice is composed of. The point is – a standard is set that will be used to begin the chain. This standard is the reference that all other measurements down the chain are going to be traced back to.
  3. Going down the chain, we compare the measurements of the next instrument to be checked against the N.I.S.T. measurement , then document the differences in the results. Depending on the conditions of the measurement, we can make the necessary adjustments needed to arrive at the most accurate measurement but can never be absolutely certain of a true value. Like much of life, we do our best. The “best” is a range of values that approximates the value of the N.I.S.T standard. This range of values is the range of uncertainty. You know that somewhere in this range, lies the true value and if you calibrate an instrument to show results within this range, you should be able to certify your instrument as calibrated according to the standard. If along the way, you lose the reference, your instrument cannot be considered to be calibrated according to the N.I.S.T. standard.

I know! This is a rather crude, simplistic explanation of the process. I “did my best”!

I got further confused after my visit to the supermarket today. They had fresh whole chickens on sale with a limit of 6 Kg per customer. For the customer’s convenience, a scale was placed near the chickens, allowing the customer to verify the total weight of his selection. The trick was to see whether you could get four chickens for 6 Kg, despite the average weight of 1.55 Kg per chicken. You do the math now. It seemed a shame to buy only three chickens and thus not take full advantage of this special sale. Four chickens were over 6 Kg and three were under by quite a bit.

Chicken

Photo credit: P. Naumann

Well, I came pretty close. I managed to find two smaller looking birds and my total weight on the scale (when last was it calibrated, I wonder?) was 6.14 Kg. I went over to the poultry supervisor and told him that I was a little over the maximum weight allowed, and with a smile on his face, he said, “That’s fine.”

<!–Here’s the moral of my little story–>: The more accurate our measurements are, the more honest we can be in our relationships with customers, clients, and other businesses. However, sometimes in life a little uncertainty goes a long way when it comes to give-and-take with others. <!–End of moralizing–>

Of interest:

 

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Three Ways to View Power Analyzers on Used-Line.com

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Do you know that there are at least three ways (maybe there are more) to view Power Analyzers on Used-LIne.com? Of course, the same applies to many of the other categories on Used-LIne. But today we are going to focus on just one instrument category – power analyzers – for illustrative purposes.

These three paths all serve different purposes. Used-Line has so much to offers its visitors!

1. View Power Analyzer Listings

Let’s talk about listings first because this is why a potential buyer of a power analyzer will visit Used-Line.com.

How do you find power analyzer listings on Used-LIne?
Well, I could send you the Used-Line Help manual. No. Let’s be honest. Which of our users really need help finding equipment listings on our website?

You probably fit into one of the following four user profiles:

  1. You are a frequent visitor to Used-Line and have been for years, and could probably give a class on how to navigate our website.
  2. You’ve been keeping up with our blog (you have, haven’t you?), and have learned all the tips and tricks for browsing equipment on Used-LIne.
  3. This is your first visit to the Used-Line website. You are in the market for a power analyzer and your favorite search engine brought you here.
  4. You have no interest in power analyzers or in test equipment in general. You simply enjoy reading this blog!

Profile 1: You know what you’re doing.
Profile 2: You’ve learned what to do.
Profile 3: Used-Line developers have made searching on Used-LIne such a cinch, there is no need for instruction.
Profile 4: Keep on reading!

So, no instructions needed – only a link: Used-Line Power Analyzer Ads.

Now that you’ve seen the listings, how about some descriptions of the various power analyzers that are listed?

Which takes us to Used-Line’s specifications pages for test and measurement equipment.

2. View Power Analyzer Specifications

If you followed the link to the power analyzer listings on Used-Line, you will have noted that there are 871 listings (as of today’s date)! Of course, you may have already decided which model you want, or you are a dealer looking for a specific manufacturer’s analyzer for one of your customers. But, what if you’d like to know a little more about a particular model? Or you want to check specs and features of a number of models before making your purchasing decision? What kind of power analyzer operation modes are essential to your work environment? Is harmonics measurement a must-have feature?

In other words, you would like to learn more about what types of analyzers are available and drill down into some specific characteristics about the various models in the market.

Here’s what you can do:

    1. Visit Used-Line’s T&M Specifications pages.
    2. Choose Power Analyzers.
    3. Browse the analyzers if you wish, then select one that you are interested in, for example, the discontinued Fluke 435. And here it is.
      Used Fluke 435 | used-line.comFind your used Fluke 435 Power Analyzer at used-line.com, the Online Marketplace for used Test and Measurement equipment.

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And here’s the best part! After studying the specs and features of the Fluke 435, you may decide this is just what you have been looking for. Scroll up the very page you landed on to view the Fluke 435 features description and you will find all the current Fluke 435 listings on Used-Line.

3. View the Power Analyzer Glossary

Yes, Used-Line actually provides a glossary of terms. Most, but not all the terms, are key specifications organized by instrument. Figuring that most of our users are familiar with the specs of the instruments they are interested in, we’ve hidden the glossary in the small fine print that can be found at the bottom of each page. Go ahead and see if you can find it. You just never know when you may need to look up a spec description while browsing our listings. Let our glossary get you started on your search for specification definitions. In case you don’t have a magnifying glass on hand, here’s the link. Of course, you want the Power Analyzer glossary, so that in case you were losing sleep wondering what Total Interharmonic Distortion really is, click below to find your answer.

Power Analyzer Glossary Terms | used-line.comA power analyzer, also known as an energy analyzer, is an electronic device that measures single-phase or three-phase electrical energy as it flows through a circuit or is distributed through electronic or motorized equipment. Electrical measurements commonly taken with a power analyzer include volts, amps, watts, frequency, reactive power hours, maximum power, phase angles and harmonic distortion.

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And you thought that Used-Line is just a market place for pre-owned hi-tech and scientific equipment?! Of course, it’s that! And much, much more.

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Used-Line Tip: Searching for a Specific Model

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Do you ever find that because some equipment model numbers are so ubiquitous, when you search for them on your favorite search-engine or on Used-Line, they will return way too many results, most of them will not be connected to what you had in mind, and the model you were trying to find will only show up on page 7 of the results?

Of course, if you search for model Z3RA29-56L3 (not a real model number as far as I know), you are very likely to find what you are searching for on page 1 of 1. However if you search for model 123  (this is a real model number) on Used-Line, 300+ results could be returned, with a very low relevancy in terms of your personal search. The reason: Many manufacturers name their equipment models using numbers that include 123 in this exact sequence. Examples: 123, 12338, 1232A, 1230T, 123R, SPS-1230, 102-123, and so on.

As you must realize, searching for a model number made up of numbers exclusively – no letters – makes matters worse. The descriptions and synopses that accompany your results may contain your model number in a price tag or even in a specification. Take a look at this Used-Line listing for a Tektronix 492 spectrum analyzer, which showed up in the results of my search for a 123 Fluke ScopeMeter.

Search result based on specs in listing description.

Search result based on specs in listing description.

Do you see why my search pulled in this listing? The amplitude range is –123 dBm to +40 dBm.

So, what to do about this?

Well, you can code some new search algorithms and send them along with your resume to the recruiting department of your favorite search-engine.

Or, you can fiddle with various settings in your search engine to train it to guess what you are looking for. And, of course, in some search engines, you can use an advanced search function to search for an exact term. But this all takes a few steps.

So, take a look at what our developers at Used-Line have done to make searching a cinch.

Used-Line has reduced the number of steps typically required to narrow down a search –  to a single click. Here is how it works. We will use model 123 as an example.

Used-Line drop-down list for model #123 search

Drop-down list for model #123 search

  1. In the menu bar near the top of any page on Used-Line, start typing 123 in the text box that is prefilled with the words, Find Category or Model#.
  2. Wait for a second or less to view a drop-down list of all the models on Used-Line that contain the number 123, such as SEM123D, 1123A, 212359, and 011-0123-00.
  3. Select model number 123 from the list.

What we have actually done here is to select a specific model. When we previously searched for a 123 and simply waited for the results to come in, the system returned the 300+ models on Used-Line that contain the number, 123. Now, after picking the specific model number, 123, from a selection of suggested model numbers, the system returned 20 models – all exactly what we were searching for. Not only has our search been narrowed down – it has zoomed right into what we were looking for.

No more clicking back and forth between pages and pages of irrelevant search results.

Now you give it a try!

 

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What to Consider when Purchasing a Digital Multimeter

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The Digital Multimeter (DMM) is the most fundamental test and measurement instrument in the electronic technician kit or engineer’s lab bench. It provides a number of functions, the most common being resistance, voltage and current. Secondary functions can include temperature, induced current, low frequency measurement, and other routine tests needed to troubleshoot circuits.

DMM types

Many technicians use more than one digital multimeter, as they tend to be designed to suit a particular purpose in various environments. A DMM used in a clean room or laboratory is totally unsuitable for use in an outdoor environment or under harsh or hazardous conditions. In practical use, the DMM may need to be operated while wearing gloves during an ice storm, or may need to be handheld, extremely compact, and lightweight for portability. They can be rack mounted in a semi-permanent installation to be in close proximity to equipment that needs to be constantly monitored.

Here is an example of a DMM that can operate in temperatures below -40°C: The Agilent U1273AX.

U1273AX Specifications and FeaturesLearn more about the various features and specifications for the U1273AX.

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DMM accuracy standards

Some DMMs are functional and practical, even without routine regular calibration certification. When the tolerance of a resistor may be 10% or 20%, a DMM accurate within 3% is generally sufficient. In the days of analog D’Arsonval meters, parallax distortion and the vagaries of electromechanical movement could result in erroneous readings near 2 to 3%. DMMS are far more stable and immune to misinterpretation of the readout.

 DMM longevity

DMMs have a relatively high attrition rate. This is the result of multiple meters required by each technician in the field and not so much a failure of an instrument. DMMs are designed to be used hundreds of times a day, both in laboratory and field conditions. Field equipment is often subject to abuse from impact of a dropped instrument to total immersion in water and similar environmental hazards. Laboratory equipment needs to be replaced as technologies advance and evolve.

DMM features

DMMs are basically the same instrument, regardless of the make or model. What distinguishes one from another are cosmetic appearance and the user interactive interfaces. Each of these differences are highlighted as features. Not every meter can have every feature; it is up to the technician to know which configuration on a DMM is optimal for any given situation.

DMM advanced or enhanced features

Some typical enhancements include dual displays, RS-232, USB or IEEE computer interfaces, audible alarms or tone feedback, which enables the technician to keep his eyes on the device under test rather than on the meter. High-priced options include very tight measurement tolerances. Some enhancements can include backlit LCD displays, as opposed to LED displays. Induced current “clamp meters” and similar exterior measurement accessories are usually optional, but may be included as a part of a package. Some features include hold and store min/max readings, auto-ranging or auto-sensing circuitry and similar hands-free operation. If multiple and various readings are necessary, these features can offer a vast improvement over manual ranging and repeated button-pushing to change DMM settings.

Here is a DMM with a USB host port on the front panel: The Tektronix DMM4040.

DMM4040 Specifications and FeaturesLearn more about the various features and specifications for the DMM4040.

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 Advantages of used DMMs

Of course, this is where Used-Line comes into the story. Leasing companies, larger companies employing scores of technicians, or smaller small- to medium-sized businesses seeking to stay within tight budgets can be well-served by considering procurement of used and re-certified, discontinued models or factory-refurbished DMMs. This is a cost-effective solution that will serve the company now and into the future. All technicians have particular makes and models of test instruments that they have high-confidence with using every day. In field applications, many techs prefer Fluke and Simpson meters for their ruggedness, durability and useful features without resorting to gimmicks or unnecessary bells-and-whistles. Given that some DMMs can cost over $10,000, depending on the degree of precision and accuracy required, buying used or as-new discontinued instruments can make or break a budget.

 Selecting the right DMM

Choose the best quality instrument that meets your need. With higher-priced test equipment it is a wise idea to lease an instrument to ensure its suitability to the task. Realize that equipment turn-over for many of the top leasing companies is due to deprecating features or advancing technology. Leasing companies frequently sell their equipment to used-line.com clients in sufficient quantities to make offering them at steep discounts possible, with no sacrifice to name-brand quality, dependability and service.

We can’t exit this blog post without showing a Fluke. If you’re looking for 365-day stability, have a look at the Fluke 8508A reference multimeter.

8508A Specifications and FeaturesLearn more about the various features and specifications for the 8508A.

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Where Can I Find a Clintec Automix 3+3 Compounder?

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Probably not at a Walmart store.

And why would I want a Clintec Automix Compounder?

Well, personally, I don’t actually need one – but – according to the stats on Used-Line, quite a few of our users do.

Before we look at the statistics, let’s try to describe what a Clintec Automix Compounder is. It is not a gas chromotograph, which was discussed in our most recent blog about the Agilent 5975. After doing your compounding thing with the Clintec Automix, you could then use the Agilent 5975 to separate and analyze what you compounded, but why would you want do to that? You would be reversing the process, wouldn’t you?

The Clintec Automix Compounder is a parenteral nutrient compounding system. If I understand this correctly, parenteral nutrient compounds are compounds that are administered by circumventing the digestive system. The compound is often fed intravenously.

Saline solution for IV

Saline solution for IV (Photo credit: Wikipedia)

Most of us are familiar with IV (intravenous) lines, but are less familiar with the processing of the mixtures that are inserted into the IV lines. This is where  compounding systems come into the picture. The Clintec Automix 3+3 Compounder is one such system. It is an automated system, and it can handle the processing of large volume ingredients, such as water and glucose.

Now let’s move on to the statistics.

Last month, July 2013, the terms, “clintec automix” were used in Used-Line searches 199 times. These two terms used together took up position number three in the top 100 search terms entered by visitors. Similarly, Google Analytics revealed that “clintex automix” was used in 72 Unique Searches on Used-Line, placing the terms in position number one for the month of July.

July 2013 Stats for search term, "Clintec + Automix"

AnalyticsCountUnique SearchPosition
Google 721
Used-Line1993

So where can you find a Clintec Automix 3+3 Compounder? On Used-Line, of course!

If you are in the market for a Clintex Automix compounder (you may be one of the 72 unique searchers who contributed to our July statistics), Toronto Surplus & Scientific has listed a Clintec 2M8286 Automix pump module on Used-Line. Toronto Surplus & Scientific Inc. has provided the following specifications on their own website:

  • Delivery Volume Range: 10 – 5000 ml
  • Specific Gravity Range: 0.50 – 3.00
  • Dimensions: 20.5″ W x 12.5″ D x 21.5″ H

If the pump module is not specifically what you want, you can post your own want list in the Used-Line Wanted System, which sends out a daily list of wanted items to all registered dealers. We will be talking about the ULWS soon! Watch for it!

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Agilent 5975 Gas Chromatograph Analyzes Vegemite Yeast Extract

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I know this is a cliche, but either you love it or you hate it. We’re talking about Vegemite. Actually, I’ve never tasted Vegemite, but I love to eat Marmite, a British and South African almost-clone of the Australian Vegemite. The rest of my family hates it. How can you kill a piece of toast with that extremely salty, hard-to-smear, strong smelling stuff, they ask?! In answer, I tell them that the trick is to spread a generous helping of butter on your toast, followed by a thin layer of Marmite. (If you’re avoiding either fat or salt, forget about it.)

But there is no need to convert the converted and I doubt I’ll be able to sway those diehard Marmite/Vegemite objectors.

I have to “import” Marmite from South Africa, where it is kosher. I hope my cousin does not have to pay for the extra weight of her luggage when she brings me my little jars of Marmite, but the good news is that it lasts FOREVER, so she does not have to satisfy my yeast extract fix too often.

Here are two of my current jars of Marmite.

Marmite

Marmite in my kitchen.

 

 

 

 

 

 

 

 

So where does Agilent come into this culinary discussion? Well, I don’t know if the recipe for Vegemite has been as closely guarded a secret as the recipe for Coca Cola, but Renée Webster, an Australian pursuing her doctorate, has analyzed the contents of Vegemite to find the distinct chemical compounds that produce the unique odor of the much-loved (or much-rejected) yeast extract. The Agilent 5975 gas chromatograph played a major role in the Vegemite analysis by breaking up this smelly (but delicious) mass that smells distinctly of – well – Vegemite – into more than 35 compounds that smell of everyday items such as flowers, wine, and leather, and which seem to have no connection to the smell of the yeast extract itself. I’m not sure if I really needed to know what Vegemite (and possibly Marmite) is composed of. You would not normally catch me spreading anything that smells of wax – or rancid fat (yes, rancid fat really is one of the detected odors) – or sweat – on my toast!

Renée Webster conducted her analysis in three stages:

  1. Sampling: Using a kitchen knife, a Solid Phase Microextraction (SPME) sampler, and a lab oven. I wonder if she regrets sacrificing to science the sample of Vegemite she needed for her experiment – never to be spread on a piece of toast!
  2. Separation: Using an Agilent 5975 GC/MSD (gas chromatograph with mass spectrometer) to separate the Vegemite compound into its multiple chemical components for individual analysis. The 5975 is built with 7890 GC technology. The gas chromatograph is responsible for the separation part of the process.
  3. Analysis: Using the mass spectrometer that, together with the included software, analyzes the detected chemicals. Hmm, couldn’t she simply use her olfactory system, that is, her nose, instead of the mass spec? Well, that might not be ideal if you want exact measurements, percentages, and specific odor descriptions.

According to the article, Agilent Helps Uncover Vegemite Mystique, on the Agilent News Hub, the GC performs the separation, and the mass spec does all the detection work. I’m guessing that with over 35 compounds and odors to detect, the 5975 GC/MSD is ideal because it allows for quick column changing; thus speeding up the detection and analysis process.

Here are a few of the top chemicals that were found in Vegemite, including their accompanying odors.

Vegemite Compound Analysis (Top three by percentage)

Percentage of TotalChemical CompoundAssociated Odor
43.8ethyl decanoatefruit, oil, sweet, wax
16.6ethyl trans-4-decenoatewax, leather, pear
12.5octanoic acid, ethyl esterfruity, fatty, floral, green, menthol, anise

To see the complete results of the separations and each component’s odor, you can read the Guardian’s Australia FoodBlog on the Vegemite analysis. As well, for details on the process Renée used to conduct her analysis, view her own blog.

If you are now inspired by the 5975’s work on Vegemite, take a look at the list of 5975’s currently available on Used-Line.

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Opting for an Optical Tme Domain Reflectometer (OTDR)

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Choosing an Optical Time Domain Reflectometer (OTDR) is very similar to the process used in selecting a new vehicle. The more options that are included – or added – the more it will cost. Some OTDRs are built with rugged utilities for heavy field use, others are delicate precision instruments suitable for laboratory use. Any high-quality OTDR is a significant expense; most cost as much – or more – than the majority of new motor vehicles. The same amount of thoughtful consideration used to buy a car should be used in selecting and buying an OTDR.

An OTDR is a complex instrument incorporating optical frequency pulse generators, a spectrum analyzer, and supporting user interface to determine the location of faults, relative impedance, signal degradation due to attenuation or deformity in the fiber, and often has a computer interface or plug-in modules to allow a separate computer access to the test and measurement device and data for more sophisticated online or offline analysis than may be available from the instrument alone.

Operating Environment

The first and most important consideration is where and how the OTDR is deployed when it is in use. Exposure to extreme weather, limited availability of electric power, and the required degree of portability eliminate any OTDR that isn’t ruggedized, battery powered, and reasonably sized, such as a hand-held. A rigid bench, wheeled carriage or rack mount unit used in a power- and climate-controlled clean room or engineering laboratory environment dictates a completely different set of options. It may be required that the OTDR is dual use, and trade-offs must be considered to determine the best value balanced against the risk of potential damage when in transport or in active use.

Operational Capabilities

Acquiring an OTDR should not be solely based on financial or budgetary considerations. Cost does not necessarily translate to effectiveness; a very expensive unit can be totally unsuited to measure the cable under test. If a unit is simply to be used to determine the location of a break in the cable and not more esoteric measurements, such as impedance mismatch, kinks or sharp bends, attenuation or signal losses, then it can be much less expensive than a full-feature instrument of otherwise similar size and utility.

New, Discontinued, Factory Refurbished or Used: Which is the best choice?

The only reasons to buy a new, bleeding side of the cutting edge technology are that the company is a manufacturer or the application is mission-critical. Often, a discontinued instrument offers substantial savings and superior value – often 30% or more – especially if it is a brand-new unit, simply no longer manufactured. A factory refurbished instrument meets or possibly exceeds the original specifications. These units are typically factory warranty returns, leased instruments, trade-ins for upgrade to newer models and similar light-use applications reconditioned by the OEM for resale. Savings of 30% to 50% are not unreasonable expectations. Used instruments can offer very high value, however, due diligence is required to ensure ample time – typically 30-90 days – for inspection and return privileges if the unit fails to perform. Cosmetic exterior wear and tear consistent with its operating environment are not uncommon. Used units that perform to specification can realize values from 60% to 90% below the original MSRP.

Brand name or OEM?

Some people are comforted by particular makes and models of test equipment. In many cases, the difference between a name-brand device and its OEM equivalent are cosmetic – the internal circuitry is identical. The wise buyer will consider the specifications before the name brand, the reliability and integrity of the source of the equipment and the particular requirements of the technician or engineer that will use the equipment. The length and scope of any warranty or guarantee must also be considered, especially with used instruments. Is the warranty a factory warranty or outsourced to an unspecified third-party?

Relative value

An OTDR can easily cost 20 to 50 thousand dollars or more. Used OTDRs can also cost 40 thousand dollars or more. A capital expense item of the magnitude of an OTDR can have significant tax implications. The ROI of a used unit often is much faster than a similar new instrument and it can have a steeper depreciation. Before purchasing an OTDR, it is suggested that the engineering staff that will be using the device, the accounting staff that will handle the budgeting and payments, and the executive officers that will have to justify the expense, be in agreement. This can be difficult; however, the use of an independent third-party systems consultant can often provide assistance in coordinating the various aspects of an acquisition with minimal impact on limited corporate resources. Before opting for a low-cost solution, consider the functionality, specifications, and usability requirements of the tasks that the instrument will be used for.

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Three Test & Measurement Instruments You Can Create with a Smartphone

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Should I be embarrassed to even admit that I don’t own any kind of smartphone? I own a Kindle. Does that count? Somehow, I don’t think so.

But despite not being able to try this out for myself unless I borrow my brother-in-law’s iPhone or my  niece’s Android phone, this is the first thing that has really tickled my fancy about smartphones (aside from Waze).
3 Test & Measurement Instruments You Can Create with a Smartphone Signal Generator, mixed signal… Click To Tweet

Test & Measurement Instruments

Test & Measurement Instruments

Anyway, back to the topic. I’m talking about turning your smartphone into a test & measurement instrument. Not a surprising development. And not that new, either. For some time now, we’ve been watching T&M instruments approach the size of smartphones. Handheld T&M instruments, while not necessarily offering the type of specs you’d find on a benchtop, have been finding their niche in the market as engineers are called upon more and more to leave their benches and go out into the field without the inconvenience of a heavy bag.

I don’t think smartphones are ruggedized enough yet to withstand the conditions that handheld T&M instruments are built for, although according to an article in the National Instruments Developer Zone, smartphones do have the potential to at the very least take over handheld  meters in the field.

Anyway, let’s take a look at just a few sample products (there are many more out there), and see what we can measure with a smartphone.

 The ‘Scope on a Phone

This should be a cinch, right? Simply show voltage over time? Yes, but what scope leads do you use? Do you need some sort of external hardware module? If you short two pins on your Device Under Test – will you fry your smartphone? What happens if your phone rings while you’re checking the output on pin 3 of your 7400? (I did not invent this question!)

In 2010, Onyx Apps introduced Oscilloscope 1.0 for iOS. The write-up on DailyAppShow describes the features and capabilities of this app, which can also generate sine, square, triangle, and sawtooth waveforms up to 22 kHz. Instead of using the  audio input, which is somewhat limiting in terms of sampling and frequency, the Onyx scope app uses the microphone or a device plugged into the microphone input. Today, Version 1.9 is available. This app offers many of the typical features you would find on a desktop oscilloscope, such as triggering modes (Normal, Single, and Auto), screen capturing ability, reference signal calibration, and more.

The Mixed Signal ‘Scope on a Phone

Believe it or not!

How did they do that? We can thank Oscium for its Model iMSO-104 mixed signal oscilloscope (MSO) for iPad and iPhone, which consists of a module that includes one 8-bit analog channel and a four-input digital harness.
3 Test & Measurement Instruments You Can Create with a Smartphone Signal Generator, mixed signal… Click To Tweet
You might need something a little more serious for devices in the GHz range, but with a 5 MHz analog bandwidth, a sample rate of 12 MS, and the ability to instantly probe a circuit from a tiny device powered by an iPhone or iPad, who’s complaining? The software app is super user-friendly, replacing knobs and buttons easily with those adept key strokes and finger swipes.

Here are some interesting pointers I learned from the FAQ on the Oscium site:

  • The analog channel can be used for measuring AC or DC. Maximum voltage range is -40 V to +40 V (10x mode).
  • Digital threshold is 1.7 V (fixed).
  • Triggering is available up to 100 ms. What’s really cool is that if your timescale goes higher, the triggering menu disappears. Although this can be scary when you first encounter this phenomenon, it’s a user-friendly tip once you’ve learned why or when this occurs.
  • The IMSO-104 is supported by iOS version 5.0 or higher.

 A Do-It-Yourself Signal Generator

Test & Measurement Instruments

Test & Measurement Instruments

An article that appeared this month in an EDN Network newsletter does not consider the 20 Hz to 20 kHz frequency range of a smartphone’s audio plug to be a limitation. There’s a lot you can do in this range. The article suggests that many of the components in medical devices fit into the lower end of the range. Here are some examples found on the National Instruments site:

  • ECG (or EKG): 0.01 – 300 Hz
  • EEG (electroencephalogram): 0.1 – 100 Hz
  • EOG (electrooculograph): 0.1 – 10 Hz
  • EMG (electromyograph): 50 Hz – 3 kHz

With the availability of hardware and software for less than $20 (not counting the cost of the smartphone!), and some light labor (get out your soldering iron) you can be up and running in no time with two channels (your left and right stereo connections) generating sine, square, and sawtooth signals.


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Why not rent? (Part two of two)

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In the last blog, I introduced a  February 2013 Scope Junction article that delivers the results of a survey on scope rentals. Readers were asked how often they had rented an oscilloscope. Of the 152 users who responded, more than 53% answered in the negative – they had never rented a scope.

Part One of this blog discussed a couple of points to consider if you are thinking about renting or leasing equipment instead of purchasing. Affordability was weighed against cost-effectiveness and the number of variables that can impact the ultimate cost of an instrument . As well, predicting the future of the industry was considered a factor in rental decisions.

Here are a couple more considerations.

Flexibility. You can rent state-of-the-art equipment that your budget does not allow you to purchase. For specific projects with stringent high-end specification requirements, a short-term rental lets you perform specialized tasks that you normally would not be able to run without the unique instrumentation features or specifications required for them. And – without breaking the bank. Although the flexibility of this type of short-term rental is attractive, it does demand more than a comfort level with the specs in order to match those required by the project with the capabilities of the instrument you intend to rent.

Test-drive an instrument. While renting, you can gauge an instrument’s performance strengths and weaknesses in your lab. Many instrument dealerships offer both rental and leasing terms. After leasing for a particular time period, you may be offered purchasing options at reduced terms. At this point, you should be able to clearly assess the suitability of the instrument as a permanent fixture in your lab.

And now for a little bonus tidbit. Or should I call that tipbit?

How to Find Dealers that Rent Out Equipment on Used-Line.com

The Used-Line Dealer Directory lists more than 900 dealers. How do you locate those that do offer rental equipment as one of their services?

  1. On the Used-Line.com home page, click DEALER DIRECTORY in the column on the right side of the page.
  2. In the Dealer Directory, use the filter on the left side of the page to choose the type of equipment you need: T&M, Lab, or Semi.
  3. Narrow your search further by Location and by product Specialization.
  4. Open the Services list, then select Rentals to view all the companies that offer rentals in the type of equipment you need.

    DD Services with Rentals

    DD services with rentals

 


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Why not rent? (Part one of two)

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In a February 2013 Scope Junction article, Michael Dunn delivers the results of a survey on scope rentals. Readers were asked how often they had rented an oscilloscope. Of the 152 users who responded, more than 53% answered in the negative – they had never rented a scope.

I’m wondering – why not?

Well, I know that there is that warm, fuzzy feeling one gets from owning one’s own stuff. There’s also the Guiltfree Factor. If you own something, you don’t get that oh-no-it’s-not-mine reaction when you spill your morning coffee on the bezel.
But, emotional issues aside, what’s on the plus side for renting a scope – or any piece of test or laboratory equipment? Here are just a few well-known, but worth repeating, advantages of renting equipment.

Affordability. Rental can be more affordable than purchasing, particularly for short-term periods and if support and maintenance are included in the terms. However, the cost of both renting or purchasing equipment needs to be carefully calculated. There are many variables, including natural depreciation of the instrument, usage, the condition of the instrument (new, used, refurbished, calibrated), specifications, configurations, need for support and repair, and yes, even size. The cost of a portable spectrum analyzer, for example, cannot be calculated using the same formula as one would use to cost a roto-molding independent-arm machine. Every company must, of course, use its own formulae for calculating the cost-effectiveness of renting or purchasing equipment.

No need to be an industry prophet. When you purchase, you need to factor in the future. When you rent, you can, well, not ignore, but somewhat downplay the effects of depreciation, usage, repairs, growth and changes in the industry, and internal turbulence within your company. You need not spend too much time wondering how much dust your instrument may be gathering at the end of the warranty period, or whether it will still be happily chugging along. A child’s “I need it now” philosophy very much suits the rental option. A year down the line is not really significant because you can swap the unit, or simply not renew the rental contract.

Stay tuned for part two, in which I’ll talk about a couple more rental considerations, and more.


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