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Old 4th May 2020, 9:33 am   #1
Chris55000
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Default Writing a test equipment theory and repair book?

Hi!

I would like to begin, at some date in the not too distant future, writing a practical book on the theory and repair of test equipment covering most types of T & M used on this and the EEV Blog Forum.

What are the practicalities of this and what sort of investment would be needed?

I want to use my knowledge and experience to write something as easy to read as anything from Gordon King or Mr. Hellyer!

I am thinking of writing the book in four parts:–

1) Measuring and indicating equipment;

2) Signal sources and generators;

3) Power supplies;

4) oscilloscope's and spectrum analysers.

I propose to incorporate a simple construction project in each chapter, relavant to the material under discussion.

If anybody has any input, comments or suggestions, I'm all ears!

Chris Williams
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Old 4th May 2020, 10:14 am   #2
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Default Re: Writing a test equipment theory and repair book?

The less mainstream instruments are likely to be the ones where people most need guidance.

Network analyser
RF power meter
Noise figure meters and noise sources.
Grid dip oscillator
Q-meter
LCR bridge
ESR meter
VSWR meter
Directional couplers, hybrids, circulators, isolators, stub tuners, sliding lines.
Distortion and SINAD meters
Attenuators

Two or three lifetime's work

If you start with the basics, it'll help the largest number of people soonest, but some people do get themselves into an almighty fix with the less mainstream stuff.

David
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Old 4th May 2020, 10:33 am   #3
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Default Re: Writing a test equipment theory and repair book?

It depends on your target audience, if you are targeting the relatively experienced members then David's comments are dead right, however if your intention is to target new members with little or no experience then you need to cover the basics. Save David's list for volume 2.

Peter
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Old 4th May 2020, 11:01 am   #4
Malcolm G6ANZ
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Default Re: Writing a test equipment theory and repair book?

Since cheap automatic testers are now readily available a short lesson on how to use them and, more importantly, how to interperet the results.
I'm thinking of the testers that can identify transistors, diodes, resistors capacitors and ESR suas this type: https://www.amazon.co.uk/Digital-Mul...NsaWNrPXRydWU=
Others are available
Malcolm
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Old 4th May 2020, 12:04 pm   #5
Chris55000
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Default Re: Writing a test equipment theory and repair book?

Hi!

It was exactly things like the various relatively cheap testers Malcolm G6 mentioned for which information is either in Chinese, fragmented or non–exsistent that the book is intended – I intend my book to be written for new Members who have, or buy, a piece of inexpensive equipment that fails or needs setting up!

It won't be written on the basis you have a whole lab–ful of gear, and other RF gear is limited to spectrum analysers, etc.,of the type most average members are likely to own!

Circuits, examples, photos, etc., etc., will be taken from either my own personal collection or redrawn from manuals freely available on the net, and in the case of photos on Forums, I'll ask the poster for permission to reuse their pics as illustrated examples!

Chris Williams

PS!

Where appropriate, I intend to include at least one valved piece of equipment in each chapter!
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Old 5th May 2020, 12:30 am   #6
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Default Re: Writing a test equipment theory and repair book?

Excellent idea and the idea of not needing a master degree, to interpret the writing sounds spot on! I would suggest you don't need to go further than the simple stuff to start with and maybe to have a look at the loads of "old" equipment that is available very cheaply at flea markets, boot sales and eBay. As Peter ( Electronpusher0 ) suggests, leave the complex stuff for chapter two .

As an aside, I have quite a few publications from the 60's and 70's that deal specifically with simple' but highly effective test equipment gleaned from various magazines of that time. As you know there are hundreds more available from www.americanradiohistory.com and www.freeinfosociety.com as well as others that I cannot think of just now. I would certainly help in supplying any information that would make the job easier.

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Old 6th May 2020, 12:02 am   #7
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Default Re: Writing a test equipment theory and repair book?

I remember one other excellent site:-

https://archive.org/

Joe
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Old 6th May 2020, 10:56 am   #8
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Default Re: Writing a test equipment theory and repair book?

Chris, that's a great idea.
In recent years, I've occasionally pestered Moderators about the possibility of the vast wealth of information in thread posts on AVO VCM's being shoehorned into one super "sticky" thread. But seemingly this is just too complicated. I can appreciate that. Then I thought that it would be great if some keen 21st century computer experienced software Forum guy could take up the challenge. The same could be applied to other items of expensive test gear, HP, TEK, etc.
Trouble is, these days, some folk are acquiring really expensive items of test gear such as CT160's, then start prodding inside with screwdrivers & pliers as though they were a cheapo clapped out DAC10 or something. The same could be said about HP stuff. God forbid, (as David will no doubt confirm), someone has to purchase genuine HP parts from Agilent, or even more expensive - get them to do repairs or calibration.
So Chris, you've got my support. Possibly you could contact the BVWS & see if they would let you do a trial article or two in the Bulletin Magazine, with a view to seeing how it would be received in the vintage radio fraternity.

Regards, David
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Old 9th May 2020, 11:17 am   #9
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Default Re: Writing a test equipment theory and repair book?

Hi!

Here's a brief resume of the contents of the initial chapters:–

Part 1 General

Ch 1 Electrical Safety Precautions
Ch 2 Other precautions when dealing with T and M equipment

Part 2 Principles of Measurement 1 –"Passive" instruments

Ch 3 Introduction to Electronic Measurements
Ch 4 The Moving Iron and Moving Coil Meter
Ch 5 Basic Multimeter Principles
Ch 6 Fault Location and Repair of basic multimeters
Ch 7 Build a Simple Multimeter

Part 3 Principles of Measurement 2 – Analogue Meters with Electronic Amplification

Ch 8 Introduction to the Valve Voltmeter
Ch 9 Practical Valve Voltmeter circuits explained
Ch 10 Fault Finding and Repair of Valve Voltmeters
Ch 11 Transistorised Electronic Voltmeters
Ch 12 A Commercial Design Analysed – The Avo EA113 Electronic Voltmeter
Ch 13 Fault Finding and Repair of Transistorised Voltmeters
Ch 14 Build a High Stability Valve Voltmeter
Ch 15 Build an Automatic Ranging Electronic Multimeter

Chris Williams

PS!

Unlike most commercial publications, all my diagrams and circuits will be drawn in a standard format with consistent styles of lettering, the only exception being where I have to use screenshots!

Pictures will be in colour where possible!
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Old 9th May 2020, 2:24 pm   #10
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Default Re: Writing a test equipment theory and repair book?

Hi!

Part 4 Principles of Measurement Part 3 – Digital Instruments

Part 5 Principles of Measurement Part 4 Measurement of other common parameters

Part 5 will include bridges, RCL meters, ESR meters, measurement of frequency, phase, impedance, and power. Some of the "cheapie" Chinese instruments will be analysed in this part.

In Part 6 I move onto power supplies, Part 7 will cover low frequency signal sources, typically up to 10MHz.

Chris Williams

I forgot to mention this will end up being a weighty tome when completed, and I intend it to be freely distributed under a CC–BY licence.

Acknowledgments of sources will be stated wherever possible!
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Old 9th May 2020, 2:45 pm   #11
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Default Re: Writing a test equipment theory and repair book?

As a gesture of support, I can take and donate some photos of the EA113 for you.

David
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Old 9th May 2020, 4:34 pm   #12
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Default Re: Writing a test equipment theory and repair book?

Hi Chris,

I admire your enthusiasm and ambition - your proposed topics look really interesting to me, as I'm sure they would be for other forum members.

However, having trodden a similar path myself some years ago (see my 'About Me' for details of the book), perhaps one or two personal reflections might be helpful.

My book was aimed at college and university students and was written from a practical/experimental point of view, but avoiding the 'cookbook' approach. It's been reasonably successful. Who would you expect to be buying your specific book? Would the readership extend beyond the typical member of this forum? How many might you sell?

How do you plan to interest a publisher in bringing it to market? Or do you plan to self publish?

Unless you're a J.K. Rowling, it's not going to make your fortune. 'Pocket money' is all you can expect.

Estimate the time it'll take and multiply by four. The reasons are:
a) initial enthusiasm leads to underestimating
b) as you get into it, you typically find a need to fill gaps in your own knowledge by further study and research. That takes lots of time unless you're quicker that I am.
c) there may be some formalities such as copyright issues to sort out.

So, in summary, if it's as comprehensive as you promise, it'll be very interesting and valuable. However, it won't provide you with a living.

I agree totally with you that there's a great deal of information buried in these forum pages and if your book could extract and summarise some of it, we'd all drink to that. But please go into it with your eyes wide open.

Best of luck!

Martin
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Old 9th May 2020, 5:42 pm   #13
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Default Re: Writing a test equipment theory and repair book?

I wrote the oscillators and synthesisers chapter for the ARRL handbook. Because it was going to be read by the widest spectrum of people, it had to be written to provide the basics for beginners, and not to bore the experts. Quite an interesting balancing act. It turned out as something that could be re-read several times with people picking up more of the subtleties each time, yet not discouraged on the first time. The ARRL were rather pleased with what they'd got. Money-wise, it was a one-off payment, about the page rate of a magazine article, but I was doing it to repay a debt I owed their 1956 edition I was loaned back in the sixties, that helped get me going. So I spent it on a memento. It has lived on my left wrist for 27 years.

David
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Old 9th May 2020, 8:56 pm   #14
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Default Re: Writing a test equipment theory and repair book?

As David says, some things can be read and read again, with benefit every time. In the late '60s I was technical manager on a pottery site, but had too much time and too little work. However there was a library of technical reports some going back to the beginning of the century, so I read them all bit by bit. Then I came across an article written by a kiln engineer, with more sense in about 8 pages than I had met before or since. I "borrowed" that magazine, still have it, and re-read it many times, using its principles to try to educate others who "already knew everything".
Ten years later, as energy manager for the group, with 20 factories and hundreds of kilns I decided I could write a book covering this much neglected area. I planned it out in my head, how I would do it, but then suddenly had a bell ring. I expected to sell this and make money, but realised it would be impossible to get it published, and there may only have been a few potential customers who would want to read it. I gave up at that point.
Of course today, whilst there would be no customers left, the publishing side is something anybody can do.
Hartley, you have missed the point here. Chris intends to make this FREELY available, a bit like Linux.
Les.
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Old 9th May 2020, 9:29 pm   #15
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Default Re: Writing a test equipment theory and repair book?

His!

I forgot one important point about "Part 5 – Measurement of other Common Parameters" – Distortion & I.M. Analysers will be included in this section!

Also:–

Part 8:– Medium and High Frequency Signal Sources;
Part 9:– Oscilloscopes, Spectrum Analysers and Logic Analysers;
Part 10:– Device Testers, Curve Tracers and Programmers

I think that covers about everything, me thinks!

I'm not going to cover TV pattern generators as the closedown of analogue TV together with the demise of the CRT as a home entertainment device has made them obsolete, and most modern TV sets have a basic "self test pattern" built in nowadays!

Chris Williams
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Old 10th May 2020, 6:08 am   #16
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Default Re: Writing a test equipment theory and repair book?

I'd love someone to write a book on how an analogue scopes timebase works & how to fix it, I've never found a good explanation.

The other snag I hit is how do you fix a scope without another scope, and piles of arcane test gear. It seems everyscope needs a test/calibration plugin XP96 or whatever to fix the blooming things. Since they stopped making XP96's in 1972 and only 20 were made this leaves one a bit stuck.

Andy.
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Old 10th May 2020, 8:31 am   #17
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Default Re: Writing a test equipment theory and repair book?

Old scope timebases were simply free-running sawtooth oscillators and you shoved in a bit of the signal taken from the Y amplifier and hoped that it would synchronise to it. Best treated as historic curios, or reserve them for use in X-Y mode displaying lissajous figures in the background as most labs are required to have at least one of these running at all times.

Newer oscilloscopes use what is called a triggered timebase.

It revolves around a flip flop. Can be made of discrete transistors, a logic IC, or (gasp) a tunnel diode.

Think of the flip flop in the reset state. It just sits there indefinitely and its output turns on a transistor shorting a capacitor the voltage on this capacitor is what goes to the X amplifier to deflect the spot across the tube. Shorted, zero volts, is set to put the spot at the left edge of the tube. The flip flop also sends a signal to the tube grid/cathode power supply to blank the spot. Blanking has to be DC coupled because it can sit in this condition indefinitely.

A sample of the Y signal is compared against a voltage from a front panel pot to set the trigger point on the waveform. Ancillary controls allow you to apply AC coupling or DC coupling to the sample, also highpass and lowpass filters (set to work well for TV frame and line rates, usually) or even to switch to a sample of the mains waveform.

The output of the trigger comparator is switched to invert or not invert it to give a choice of triggering on the rising or falling edge of the waveform. This is then used to trigger the flip flop into its set state. Think of an S-R flip flop, or better a D-type with this trigger signal as the clock and a logic 1 on 'D'.

Now triggered, the flip flop turns on the beam current so the spot lights up at the left edge of the CRT, and turns off the transistor shorting the capacitor. The capacitor is fed with a constant current source, so the voltage across it ramps up, and the spot moves across the tube at constant speed.

THe capacitor value is switched in a 10, 5, 2, 1, 0.5, 0.2.... etc sequence to give coarse time/division steps of timebase speed i the main timebase speed knob. The constant current source is adjustable by a voltage from another front panel pot, the time/division vernier, usually a knob mounted coaxially with the main timebase speed switch. The speed switch markings are right with the current source at its max setting, fully clock on the vernier knob.

A comparator watches the voltage on the timebase capacitor and when it reaches the value appropriate to the right hand side of the tube, it resets the timebase flip flop. This, in the reset state blanks the spot and shorts the capacitor. X amp voltages return to the left edge values.

So, you now have an oscilloscope which shows absolutely nothing unless you have the trigger controls set right and have a signal. It doesn't even give you a clue. No wonder they confuse people.

We need to fix this. An extra pole is added to the timebase speed switch to select another capacitor. This is used in a timer. There is a switch on the front panel labelled Auto/Norm. In norm, the timer does nothing. In auto, the timer is started at the end of a timebase run and if the timer concludes its set period before the timebase runs again, it triggers the timebase flip flop. WHat this means is that so long as you get regular triggers from your signal, as defined by the trigger level pot and switches, everything works normally. If there is no such trigger happening, after a while the timebase keeps running anyway to show you something of what your signal is doing. This gives you a guide for setting trigger controls to get an normal picture.

So the timebase is routinely left in auto mode (some people are confused into thinking auto means automate the setting of trigger and amplitude controls... nope, that's different and may be found on later scopes)

If you're watching slow or erratic events, the auto runs of the timebase can be a nuisance, so you switch to 'norm' to stop them happening. Note that the switched capacitor for this timer means that the time between auto runs depends on the time/division knob setting... a convenience.

A posh scope may have a second timer set by a third pole on the time/div switch and provided with a vernier pot labelled 'Holdoff' This timer runs at the end of the timebase run and disables triggering of the flip flop for a while. This allows the user to stop the timebase becoming ready for triggering as quickly as it could... and with this you can clean up a picture where there are multiple trigger ponts that fit the settings within the waveform.

So that's what's in a single timebase scope.
A trigger comparator
A flip flop
A constant current/capacitor ramp generator
An end of sweep comparator
An auto-run timer
And maybe an holdoff timer.

Add in a few pots and a lot of switches, and voila!

To fix one, find out which state the flip flop is stuck in, then trace back to find out why.

David
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Old 10th May 2020, 10:34 am   #18
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Default Re: Writing a test equipment theory and repair book?

Quote:
Originally Posted by MotorBikeLes View Post
...........the publishing side is something anybody can do.
Hartley, you have missed the point here. Chris intends to make this FREELY available, a bit like Linux.......
Les.
Well, that’s very different then.

Maybe a sort of cooperative ‘Test Equipment Wikipedia’ with open contributions from forum members and Chris in a managing editor role?

Martin
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Old 10th May 2020, 11:25 am   #19
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Default Re: Writing a test equipment theory and repair book?

Hi Chris, I have a service manual for the Blackstar Meteor 1000 frequency counter, that I might be able to scan if it is of interest for your book. It uses the ICM7216DIPI and some Plessey chips for prescaler etc.
Dave
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Old 10th May 2020, 8:56 pm   #20
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Default Re: Writing a test equipment theory and repair book?

Hi Andy, for all you need to know about analogue timebases : Timebases by OS Puckle and The Cathode Ray Oscilloscope Parr & Davie.

Usually copies on the bay

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