New member introduction for Joe Butter


pdxareaid
 

I'm tempted to put the whole CRT/Z-AXIS design in Spice and see what happens when I change things but I really don't want to spend the time on this.
I just uploaded a new photo album 465B CRT Circuit Simulation https://groups.yahoo.com/neo/groups/TekScopes/photos/albums/1872085640.

If you are interested and register with the sim tool, I can share the project.


Background:
I debugged my 465B CRT HV circuit a while ago, and I forget how to use this thing but
it is coming back fast. I'll figure out how to share the project later.


I originally used QUCS but the engine fell apart with singularities and was useless for this circuit.
I signed up for EasyEDA.com and used it just fine. That is what the album snapshots are.
EasyEDA is for circuit design, simulation and layout and eventual fab.
I stopped with the simulation. It was free then and still appears to be. I have some beefs with it but overall
it is actively being developed and was very useful for my purpose.


There is more to this story involving no 50K oscillation and current limiting and blown fuses etc, but it is irrelevant to what I used the simulation for.


I put in the basic CRT circuit then added leaks to approach what I was seeing in real life.
I had to add a couple of models for devices I did not find in the libraries.


I had previously replaced the restorer diodes with MUR160's and they worked for a while
but i refused to believe they went bad. They were brand new. I simulated and even breadboarded the whole thing...eventually giving in and replaced them with BAV21's and all has been fine ever since.
I got a batch of bad MUR160s. From Ebay no less!!!


So if it is useful to you and you want me to share the project, I guess you drive how to communicate etc.
I'll just let it sit for now.
phil
PS. I can't hold a candle to some of the electronics wizards in here. I got thru it but I was guided by a great, very knowledgeable guy 3000 miles away.
He used to be on this forum but was kicked off when his email was spoofed. I think he crept back to lurk.

Hi Gerry, if you are there.


pdxareaid
 

i think my link to the album does not work because the period at the end of the sentence was incorporated into the link address. you can just go to photo albums to get to it.

i think i can share my project as read only to anyone that signs up with EasyEDA and from there you can clone it to a private project to hack away at your own version.


 

On 31 Oct 2017 21:52:02 +0000, you wrote:

...

I had previously replaced the restorer diodes with MUR160's and they worked for a while
but i refused to believe they went bad. They were brand new. I simulated and even breadboarded the whole thing...eventually giving in and replaced them with BAV21's and all has been fine ever since.
I got a batch of bad MUR160s. From Ebay no less!!!
I is difficult to believe that this circuit could damage MUR160s under
any circumstances.

I'm shocked, SHOCKED, to find that counterfeit parts are sold through
Ebay.


pdxareaid
 

I'm shocked, SHOCKED, to find that counterfeit parts are sold through
Ebay.

I know!! I know!! and on top of that they were from China!!! what are the odds?


Joseph Butter
 

pdxareaid,

Thanks for the offer and information. I think it might be a little much for me right now but I do have some interest. This scope (Tek 465) requires a little understanding on the circuitry and quite possibly a little luck to troubleshoot. My interest in the simulation was to keep myself from throwing parts at it (ex. capacitors, multiplier, other) and understand the circuit before messing with it. This scope has no diagnostics, a rudimentary service manual, and appears to have a condition that may not be a typical issue for the scope. The regulator for the oscillator appears to have a very weak drive signal and the frequency is off (25 kHz instead of 50 kHz) and I'm trying to figure out why. Most folks have the opposite situation that drives the oscillator too hard and it blows the fuse or the multiplier has failed and it blows the fuse.

When the restorer diodes went bad on your Tek 465B, what was the failure mode? No display at all/Partial display/unusable display/blowing fuses/oscillator frequency not correct/other??????

Thanks again for the offer.

Joe


EB4APL
 

Hi Joe,

I can only talk about faulty restorer diodes. In my experience (2 Tek
and one R&S scopes) the symptom was brightness at maximum, regardless of
the control position. All of them had developed leaks and they were
found by try and error. Once found, I replaced the whole set.

Regards,
Ignacio, EB4APL

El 01/11/2017 a las 19:02, joseph@danyabutter.com [TekScopes] escribi:

pdxareaid,

Thanks for the offer and information. I think it might be a little
much for me right now but I do have some interest. This scope (Tek
465) requires a little understanding on the circuitry and quite
possibly a little luck to troubleshoot. My interest in the simulation
was to keep myself from throwing parts at it (ex. capacitors,
multiplier, other) and understand the circuit before messing with it.
This scope has no diagnostics, a rudimentary service manual, and
appears to have a condition that may not be a typical issue for the
scope. The regulator for the oscillator appears to have a very weak
drive signal and the frequency is off (25 kHz instead of 50 kHz) and
I'm trying to figure out why. Most folks have the opposite situation
that drives the oscillator too hard and it blows the fuse or the
multiplier has failed and it blows the fuse.

When the restorer diodes went bad on your Tek 465B, what was the
failure mode? No display at all/Partial display/unusable
display/blowing fuses/oscillator frequency not correct/other??????

Thanks again for the offer.

Joe


[Non-text portions of this message have been removed]


------------------------------------------------------------------------
Posted by: joseph@danyabutter.com
------------------------------------------------------------------------


[Non-text portions of this message have been removed]


Fabio Trevisan
 

Hello Joe,
I have a 464 which had problems with the HV circuitry when it got to me.
The H.V inverter of the 464 is VERY, VERY similar to yours (it's basically
the same circuit).
In the process of solving my primary problem (which was in the H.V.
transformer... not necessarily your case) I got my original tek part
151-0140-00, a "selected" 2N3055 burned.

What brought me to writing to you is only to emphasize FURTHER (others
already pointed it out) that the 2n3055 (Q1418) in this circuit is REALLY
critical.
When my original got burnt, from about 5 or 6 different 2n3055 I tried, the
circuit only worked with one of them, and still, I needed to change the
value of a resistor, to lower a little bit its base drive current.
The one that worked on my case was the MJ15015 (Which David Hess mentioned
earlier and which he added to his list because of my case).
I tried the 2n3772 and it oscillated at an harmonic of the transformer
characteristic frequency (I think 3rd or 5th harmonic, don't remember now).
Curiousby itslef because exactly the 2n3772 has a low Ft of 200KHz, the
lower of all.
I even thought it was a fake, but I opened it up later on and it was
clearly an original part (mine was from ST).
I tried to buy from a local auction site a vintage RCA 2n3055, dated
something around 1969 (markings where too faded away). I`m not sure it's a
Hometaxial part as the original tek part is, but this one didn't oscillate
whatsoever.
I tried modern 2N3055s from different brands and some wouldn't oscillate at
all, and others would oscillate so wildly that the regulator couldn't hold
it and the H.V. went all the way to the roof.

Add to this the uncertainty around any old or used 2N3055s because of fakes
flooding the market and you have a difficult part to source or even to
assure the one you got inside the scope is up to the task.

If your Q1418 is not an original Tek part, or if it tests bad, avoid
yourself the trouble and get an original part (Qservice in Greece or Sphere
in Canada are the 2 reputable sources that everybody in this group know
that comes to my mind).
If they don't have one with the Tek part-number in it, it will at least be
from the right "family" (Hometaxial) or yet, at least known to work on your
scope.
I don't bear any relation to either of them sellers, besides their
reputation on this group.

There are already too much variables to the troubleshooting of this
circuit, to be unsure about the transistor, if it would or would not work.

I wish you luck.

Rgrds,

Fabio





2017-11-01 16:02 GMT-02:00 joseph@danyabutter.com [TekScopes] <
TekScopes@yahoogroups.com>:



pdxareaid,

Thanks for the offer and information. I think it might be a little much
for me right now but I do have some interest. This scope (Tek 465) requires
a little understanding on the circuitry and quite possibly a little luck to
troubleshoot. My interest in the simulation was to keep myself from
throwing parts at it (ex. capacitors, multiplier, other) and understand the
circuit before messing with it. This scope has no diagnostics, a
rudimentary service manual, and appears to have a condition that may not be
a typical issue for the scope. The regulator for the oscillator appears to
have a very weak drive signal and the frequency is off (25 kHz instead of
50 kHz) and I'm trying to figure out why. Most folks have the opposite
situation that drives the oscillator too hard and it blows the fuse or the
multiplier has failed and it blows the fuse.

When the restorer diodes went bad on your Tek 465B, what was the failure
mode? No display at all/Partial display/unusable display/blowing
fuses/oscillator frequency not correct/other??????

Thanks again for the offer.

Joe


[Non-text portions of this message have been removed]



[Non-text portions of this message have been removed]


Tom Jobe <tomjobe@...>
 

In this thread the 151-0140-00 transistor was mentioned as also being
used in scopes like the 7603, and I had the same experience Fabio had
where nothing except a homotaxial RCA 2N3055 would work as a replacement
in a 7603.
I think I found out about the importance of using a homotaxial 2N3055 on
the Tekscopes Group and was able to buy some from Surplus Sales of
Nebraska who had a few of them at the time (10 or more years ago?).
It looks like Walter at Sphere Electronics may have some of them in stock.
There are lots of TO-3's that are claimed to be the same or better than
the RCA 2N3055 homotaxial, and I tried many of them with no luck.
If one had enough circuit knowledge they might be able to modify the
circuit to use a modern 2N3055... but that is... and was, way beyond my
ability.
tom jobe...

On 11/1/2017 3:06 PM, Fabio Trevisan fabio.tr3visan@gmail.com
[TekScopes] wrote:

Hello Joe,
I have a 464 which had problems with the HV circuitry when it got to me.
The H.V inverter of the 464 is VERY, VERY similar to yours (it's basically
the same circuit).
In the process of solving my primary problem (which was in the H.V.
transformer... not necessarily your case) I got my original tek part
151-0140-00, a "selected" 2N3055 burned.

What brought me to writing to you is only to emphasize FURTHER (others
already pointed it out) that the 2n3055 (Q1418) in this circuit is REALLY
critical.
When my original got burnt, from about 5 or 6 different 2n3055 I
tried, the
circuit only worked with one of them, and still, I needed to change the
value of a resistor, to lower a little bit its base drive current.
The one that worked on my case was the MJ15015 (Which David Hess mentioned
earlier and which he added to his list because of my case).
I tried the 2n3772 and it oscillated at an harmonic of the transformer
characteristic frequency (I think 3rd or 5th harmonic, don't remember
now).
Curiousby itslef because exactly the 2n3772 has a low Ft of 200KHz, the
lower of all.
I even thought it was a fake, but I opened it up later on and it was
clearly an original part (mine was from ST).
I tried to buy from a local auction site a vintage RCA 2n3055, dated
something around 1969 (markings where too faded away). I`m not sure it's a
Hometaxial part as the original tek part is, but this one didn't oscillate
whatsoever.
I tried modern 2N3055s from different brands and some wouldn't
oscillate at
all, and others would oscillate so wildly that the regulator couldn't hold
it and the H.V. went all the way to the roof.

Add to this the uncertainty around any old or used 2N3055s because of
fakes
flooding the market and you have a difficult part to source or even to
assure the one you got inside the scope is up to the task.

If your Q1418 is not an original Tek part, or if it tests bad, avoid
yourself the trouble and get an original part (Qservice in Greece or
Sphere
in Canada are the 2 reputable sources that everybody in this group know
that comes to my mind).
If they don't have one with the Tek part-number in it, it will at least be
from the right "family" (Hometaxial) or yet, at least known to work on
your
scope.
I don't bear any relation to either of them sellers, besides their
reputation on this group.

There are already too much variables to the troubleshooting of this
circuit, to be unsure about the transistor, if it would or would not work.

I wish you luck.

Rgrds,

Fabio

2017-11-01 16:02 GMT-02:00 joseph@danyabutter.com [TekScopes] <
TekScopes@yahoogroups.com>:



pdxareaid,

Thanks for the offer and information. I think it might be a little much
for me right now but I do have some interest. This scope (Tek 465)
requires
a little understanding on the circuitry and quite possibly a little
luck to
troubleshoot. My interest in the simulation was to keep myself from
throwing parts at it (ex. capacitors, multiplier, other) and
understand the
circuit before messing with it. This scope has no diagnostics, a
rudimentary service manual, and appears to have a condition that may
not be
a typical issue for the scope. The regulator for the oscillator
appears to
have a very weak drive signal and the frequency is off (25 kHz
instead of
50 kHz) and I'm trying to figure out why. Most folks have the opposite
situation that drives the oscillator too hard and it blows the fuse
or the
multiplier has failed and it blows the fuse.

When the restorer diodes went bad on your Tek 465B, what was the failure
mode? No display at all/Partial display/unusable display/blowing
fuses/oscillator frequency not correct/other??????

Thanks again for the offer.

Joe


[Non-text portions of this message have been removed]


[Non-text portions of this message have been removed]


 

The 455/465M uses an improved version of this circuit with a fast (50
MHz) D44H11 type of transistor but it is not clear to me what changed
to allow this. Maybe the transformer is better?

If I get my hands on one of the 465 series oscilloscopes, I will

On Wed, 1 Nov 2017 20:06:34 -0200, you wrote:

...

What brought me to writing to you is only to emphasize FURTHER (others
already pointed it out) that the 2n3055 (Q1418) in this circuit is REALLY
critical.

When my original got burnt, from about 5 or 6 different 2n3055 I tried, the
circuit only worked with one of them, and still, I needed to change the
value of a resistor, to lower a little bit its base drive current.
The one that worked on my case was the MJ15015 (Which David Hess mentioned
earlier and which he added to his list because of my case).

I tried the 2n3772 and it oscillated at an harmonic of the transformer
characteristic frequency (I think 3rd or 5th harmonic, don't remember now).
Curiousby itslef because exactly the 2n3772 has a low Ft of 200KHz, the
lower of all. I even thought it was a fake, but I opened it up later on and it was
clearly an original part (mine was from ST).

I tried to buy from a local auction site a vintage RCA 2n3055, dated
something around 1969 (markings where too faded away). I`m not sure it's a
Hometaxial part as the original tek part is, but this one didn't oscillate
whatsoever.

I tried modern 2N3055s from different brands and some wouldn't oscillate at
all, and others would oscillate so wildly that the regulator couldn't hold
it and the H.V. went all the way to the roof.

...


There are already too much variables to the troubleshooting of this
circuit, to be unsure about the transistor, if it would or would not work.

Fabio


 

Oops, accidently sent that before I finished.

The 455/465M uses an improved version of this circuit with a fast (50
MHz) D44H11 type of transistor but it is not clear to me what changed
to allow this. Maybe the transformer is better?

If I get my hands on one of the 465 series oscilloscopes, I will test
it to see what would be neccessary for a more commonly available
transistor to work.

On Wed, 1 Nov 2017 20:06:34 -0200, you wrote:

...

What brought me to writing to you is only to emphasize FURTHER (others
already pointed it out) that the 2n3055 (Q1418) in this circuit is REALLY
critical.

When my original got burnt, from about 5 or 6 different 2n3055 I tried, the
circuit only worked with one of them, and still, I needed to change the
value of a resistor, to lower a little bit its base drive current.
The one that worked on my case was the MJ15015 (Which David Hess mentioned
earlier and which he added to his list because of my case).

I tried the 2n3772 and it oscillated at an harmonic of the transformer
characteristic frequency (I think 3rd or 5th harmonic, don't remember now).
Curiousby itslef because exactly the 2n3772 has a low Ft of 200KHz, the
lower of all. I even thought it was a fake, but I opened it up later on and it was
clearly an original part (mine was from ST).

I tried to buy from a local auction site a vintage RCA 2n3055, dated
something around 1969 (markings where too faded away). I`m not sure it's a
Hometaxial part as the original tek part is, but this one didn't oscillate
whatsoever.

I tried modern 2N3055s from different brands and some wouldn't oscillate at
all, and others would oscillate so wildly that the regulator couldn't hold
it and the H.V. went all the way to the roof.

...


There are already too much variables to the troubleshooting of this
circuit, to be unsure about the transistor, if it would or would not work.

Fabio


n4buq
 

The original parts are available:

http://www.talonix.com/shop/item.aspx?itemid=10699

Thanks,
Barry - N4BUQ

----- Original Message -----
From: "David davidwhess@gmail.com [TekScopes]" <TekScopes@yahoogroups.com>
To: TekScopes@yahoogroups.com
Sent: Wednesday, November 1, 2017 8:51:31 PM
Subject: Re: [TekScopes] Re: New member introduction for Joe Butter

Oops, accidently sent that before I finished.

The 455/465M uses an improved version of this circuit with a fast (50
MHz) D44H11 type of transistor but it is not clear to me what changed
to allow this. Maybe the transformer is better?

If I get my hands on one of the 465 series oscilloscopes, I will test
it to see what would be neccessary for a more commonly available
transistor to work.

On Wed, 1 Nov 2017 20:06:34 -0200, you wrote:

...

What brought me to writing to you is only to emphasize FURTHER (others
already pointed it out) that the 2n3055 (Q1418) in this circuit is REALLY
critical.

When my original got burnt, from about 5 or 6 different 2n3055 I tried, the
circuit only worked with one of them, and still, I needed to change the
value of a resistor, to lower a little bit its base drive current.
The one that worked on my case was the MJ15015 (Which David Hess mentioned
earlier and which he added to his list because of my case).

I tried the 2n3772 and it oscillated at an harmonic of the transformer
characteristic frequency (I think 3rd or 5th harmonic, don't remember now).
Curiousby itslef because exactly the 2n3772 has a low Ft of 200KHz, the
lower of all. I even thought it was a fake, but I opened it up later on and
it was
clearly an original part (mine was from ST).

I tried to buy from a local auction site a vintage RCA 2n3055, dated
something around 1969 (markings where too faded away). I`m not sure it's a
Hometaxial part as the original tek part is, but this one didn't oscillate
whatsoever.

I tried modern 2N3055s from different brands and some wouldn't oscillate at
all, and others would oscillate so wildly that the regulator couldn't hold
it and the H.V. went all the way to the roof.

...


There are already too much variables to the troubleshooting of this
circuit, to be unsure about the transistor, if it would or would not work.

Fabio


 

Yea, but I am one of those, "Why is this working? I must tear it
apart to find out why!" people.

On Wed, 1 Nov 2017 22:08:27 -0400 (EDT), you wrote:

The original parts are available:

http://www.talonix.com/shop/item.aspx?itemid=10699

Thanks,
Barry - N4BUQ


n4buq
 

I'm one of those "Why is this not working. I must tear it apart, try to fix it, ask a million questions to the various email lists, eventually find the problem, and move to the next thing" people.

Those xstrs are a bit high priced but I suppose if they work then...

Thanks,
Barry - N4BUQ

----- Original Message -----
From: "David davidwhess@gmail.com [TekScopes]" <TekScopes@yahoogroups.com>
To: TekScopes@yahoogroups.com
Sent: Wednesday, November 1, 2017 9:18:48 PM
Subject: Re: [TekScopes] Re: New member introduction for Joe Butter

Yea, but I am one of those, "Why is this working? I must tear it
apart to find out why!" people.

On Wed, 1 Nov 2017 22:08:27 -0400 (EDT), you wrote:

The original parts are available:

http://www.talonix.com/shop/item.aspx?itemid=10699

Thanks,
Barry - N4BUQ


pdxareaid
 

When the restorer diodes went bad on your Tek 465B, what was the failure mode?

the failure, as i recall, was in several stages:


i noticed my intensity getting harder to turn down (crt bias pot not doing what it was supposed to do) so i replaced the restorer diodes with MUR160 (probably fakes) and that worked for a while and then it degraded again. replacing those diodes is a classic repair for that symptom.
i began suspecting everything - HV caps, regulator etc. my 93 waveform was inappropriate. see leaked vs normal crt circuit simulation results pics i posted.
BTW: that posted "leak" circuit was just one i had laying around. i tried several versions
since once the basic circuit was entered, it was easy to add leaks to other components.
but i'm getting ahead of the story...simulation was not used yet.


so i had it apart, with the 50K monitored on another scope, and while
i was pondering the circuit diagram, i looked up just at the right time to see the 50K disappear. i wasn't touching the scope. turns out the fuse (near the xfmr) blew.
and the replaced fuses blew. so good!!! a hard failure - much easier. i disconnected multiplier etc and unloaded what i could and it continued to blow.
so i built a current limited power supply and embarked on a measurement program as i slowly racheted up the current.
and for some reason bringing it up slowly, it did not blow fuses even after current limit removed! and it never blew again without changing anything else. confusion reigned. i suspected everything again.
so i decided to simulate and understand circuit better and replaced MUR160's with other MUR160's (from same batch) and it improved and eventually degraded again.
lots of measurements (in regulator and you name it) later and i was getting nowhere.
i replaced the MUR160's with BAV21 and it has been stable ever since.


btw: i had a triplett analog meter i restored to measure -2450 and other voltages near crt (not multiplier output though).
that was a little too inaccurate for my taste so i used 3 series connected cheapo (free) harbor freight dmm's and got pretty good
readings of higher voltages. just add the readings together. but i stood back as i powered up :-) nothing arced or melted though...i got away with it.


Joseph Butter
 

I ordered a few (4) MJ15015 (NTE) transistors from Newark today. The 2N3055 (ST) transistors did not make any difference so I put the RCA transistor back in earlier. I will probably try the MJ15015 when it gets here and report on it.

BTW - that earlier text from my wife on my son's car resulted in a major distraction and a new fuel injector. Compressed Natural Gas vehicle and the cost of an injector was $157.

It looks like the MJ15015 is used by a lot of audio amp folks based on my searches.


Jon Batters
 

HI Michael,

Thank you,…..Thank you for your message on VOMs. I had forgotten what I knew about them.

When Richard Pope wrote about his Simpsons’ and varying input-R, an alarm bell went off. He didn’t give a model # but I know this is an old, old company still in business and there’s something funky about their meters ! Let’s see, Oh I Know; it’s the strange Ohms/ Volt Spec. Didn’t that die off after WWII ? We should not forget that some of our members may have been in the Signal Corp in 1939 and that is their experience base… How OLD is Richard anyway……? ( ha ha ) Maybe This is what some of our members are referring to re/ varying input-R ! And they’re correct, for the VOM design ! Anyway, I believe you can still buy a Simpson ( with a 4” meter movement ) Why you would want to do this against a modern design, I would enjoy learning. Interestingly, Fluke brags about their digital display Emulating a bar graph with a Meter Movement type response for doing Tuning Work !

So…….one of the things I enjoy about our group is that I can post a message and get responses from around the World. For me this can be……..you’re an idiot ( not uncommon ) to……I can explain that / to…….here’s what happened to me / to…..my favorite, Don’t ever……ever Do “This”…..

Jon Batters, Grants Pass, Or.



[Non-text portions of this message have been removed]


Richard R. Pope
 

John,
I am 62 almost 63. My Simpsons are Model 260s. I use them for audio
and tuning work. I'll come back to this. Yes you can buy new Simpsons
but they are very expensive. I used Simpsons when I was in the AF in the
early 80s. The reason we still used them was they can't be beat for
tuning working. When you are peaking or nulling out an Amplifier the
movement of a needle is much easier to follow than a digital voltage
output. You can hit a precise peak or null because of the way the needle
moves. With a DMM, no mater how many digits there is some imprecision
that is inherent in the meter. When measuring resistance you have to be
aware that the meter has a varying resistance value of 20K per DC volt
and 5K per AC volt. With audio you can follow the voltage changes on the
needle. It is cool to watch the needle move as someone talks or when
music is being played.
Thanks,
rich!

On 11/1/2017 11:29 PM, Jon Batters jonbatters32@gmail.com [TekScopes] wrote:


HI Michael,

Thank you,…..Thank you for your message on VOMs. I had forgotten what
I knew about them.

When Richard Pope wrote about his Simpsons’ and varying input-R, an
alarm bell went off. He didn’t give a model # but I know this is an
old, old company still in business and there’s something funky about
their meters ! Let’s see, Oh I Know; it’s the strange Ohms/ Volt Spec.
Didn’t that die off after WWII ? We should not forget that some of our
members may have been in the Signal Corp in 1939 and that is their
experience base… How OLD is Richard anyway……? ( ha ha ) Maybe This is
what some of our members are referring to re/ varying input-R ! And
they’re correct, for the VOM design ! Anyway, I believe you can still
buy a Simpson ( with a 4” meter movement ) Why you would want to do
this against a modern design, I would enjoy learning. Interestingly,
Fluke brags about their digital display Emulating a bar graph with a
Meter Movement type response for doing Tuning Work !

So…….one of the things I enjoy about our group is that I can post a
message and get responses from around the World. For me this can
be……..you’re an idiot ( not uncommon ) to……I can explain that /
to…….here’s what happened to me / to…..my favorite, Don’t ever……ever
Do “This”…..

Jon Batters, Grants Pass, Or.


 

Hi Jon,

Simpson 260 Meters are extremely well made and they last forever. They are highly prized by collectors like cameras, fine watches, and even LPs.

There is nothing strange about ohms/volt if you understand the context. Electro-mechanical meter movements (D'Arsonval/Weston meters for instance) uses a coil suspended in a magnetic field. A D'Arsonval/Weston meter movement can be calibrated as a DC voltmeter if the resistance of the coil is known by calculating the voltage required to generate a full scale current. To measure more voltage with the meter movement you add resistance in series with it. When you do this the basic sensitivity of the meter (measured in ohms/volt) remains constant.

Analog meters still have their place in electronics since they can be quicker and easier to read if values are fluctuating quickly. Try connecting a DVM to a random noise source and you may see what I mean.

I used a VOM for many years in the 1960s and I learned about ohms per volt at the time. For more than 100 years before I used them analog meters were the only way to measure electrical quantities. Obviously it isn't necessary to use VOMs today so there may be no reason to be familiar with the concepts behind them. Analog meters did make a huge contribution to getting us where we are today.

The first time I realized you can't do everything with a meter was when I tried to troubleshoot a flip flop with my VTVM. When I discovered that a beam of electrons could move a million times faster than a meter needle I stopped using analog meters and developed a love for oscilloscopes. I haven't looked back until now. Thanks for reminding me how strange "ohms per volt" must sound to someone who has never heard it before.

Dennis Tillman W7PF

On 11/1/2017 11:29 PM, Jon Batters jonbatters32@gmail.com [TekScopes] wrote:

HI Michael,

Thank you,…..Thank you for your message on VOMs. I had forgotten what
I knew about them.

When Richard Pope wrote about his Simpsons’ and varying input-R, an
alarm bell went off. He didn’t give a model # but I know this is an
old, old company still in business and there’s something funky about
their meters ! Let’s see, Oh I Know; it’s the strange Ohms/ Volt Spec.
Didn’t that die off after WWII ? We should not forget that some of our
members may have been in the Signal Corp in 1939 and that is their
experience base… How OLD is Richard anyway……? ( ha ha ) Maybe This is
what some of our members are referring to re/ varying input-R ! And
they’re correct, for the VOM design ! Anyway, I believe you can still
buy a Simpson ( with a 4” meter movement ) Why you would want to do
this against a modern design, I would enjoy learning. Interestingly,
Fluke brags about their digital display Emulating a bar graph with a
Meter Movement type response for doing Tuning Work !

So…….one of the things I enjoy about our group is that I can post a
message and get responses from around the World. For me this can
be……..you’re an idiot ( not uncommon ) to……I can explain that /
to…….here’s what happened to me / to…..my favorite, Don’t ever……ever
Do “This”…..

Jon Batters, Grants Pass, Or.


Richard R. Pope
 

Hello Dennis,
How are you doing? As I said I still use my Simpson on a regular
basis. Yes, I have a DMM that I use more than a VOM. I wouldn't mind
acquiring a VTVM. They are also highly respected and sought out. Yes you
can null or peak an amplifier with a DMM but it is easier and quicker
with a VOM. A DMM is more accurate measuring resistance especially very
high resistances. You are correct about the VOM still being a useful
tool. As always using the correct tool always makes things easier.
Thanks,
rich!

On 11/2/2017 2:27 AM, 'Dennis Tillman' dennis@ridesoft.com [TekScopes]
wrote:

Hi Jon,

Simpson 260 Meters are extremely well made and they last forever. They
are highly prized by collectors like cameras, fine watches, and even LPs.

There is nothing strange about ohms/volt if you understand the
context. Electro-mechanical meter movements (D'Arsonval/Weston meters
for instance) uses a coil suspended in a magnetic field. A
D'Arsonval/Weston meter movement can be calibrated as a DC voltmeter
if the resistance of the coil is known by calculating the voltage
required to generate a full scale current. To measure more voltage
with the meter movement you add resistance in series with it. When you
do this the basic sensitivity of the meter (measured in ohms/volt)
remains constant.

Analog meters still have their place in electronics since they can be
quicker and easier to read if values are fluctuating quickly. Try
connecting a DVM to a random noise source and you may see what I mean.

I used a VOM for many years in the 1960s and I learned about ohms per
volt at the time. For more than 100 years before I used them analog
meters were the only way to measure electrical quantities. Obviously
it isn't necessary to use VOMs today so there may be no reason to be
familiar with the concepts behind them. Analog meters did make a huge
contribution to getting us where we are today.

The first time I realized you can't do everything with a meter was
when I tried to troubleshoot a flip flop with my VTVM. When I
discovered that a beam of electrons could move a million times faster
than a meter needle I stopped using analog meters and developed a love
for oscilloscopes. I haven't looked back until now. Thanks for
reminding me how strange "ohms per volt" must sound to someone who has
never heard it before.

Dennis Tillman W7PF

On 11/1/2017 11:29 PM, Jon Batters jonbatters32@gmail.com [TekScopes]
wrote:

HI Michael,

Thank you,…..Thank you for your message on VOMs. I had forgotten what
I knew about them.

When Richard Pope wrote about his Simpsons’ and varying input-R, an
alarm bell went off. He didn’t give a model # but I know this is an
old, old company still in business and there’s something funky about
their meters ! Let’s see, Oh I Know; it’s the strange Ohms/ Volt Spec.
Didn’t that die off after WWII ? We should not forget that some of our
members may have been in the Signal Corp in 1939 and that is their
experience base… How OLD is Richard anyway……? ( ha ha ) Maybe This is
what some of our members are referring to re/ varying input-R ! And
they’re correct, for the VOM design ! Anyway, I believe you can still
buy a Simpson ( with a 4” meter movement ) Why you would want to do
this against a modern design, I would enjoy learning. Interestingly,
Fluke brags about their digital display Emulating a bar graph with a
Meter Movement type response for doing Tuning Work !

So…….one of the things I enjoy about our group is that I can post a
message and get responses from around the World. For me this can
be……..you’re an idiot ( not uncommon ) to……I can explain that /
to…….here’s what happened to me / to…..my favorite, Don’t ever……ever
Do “This”…..

Jon Batters, Grants Pass, Or.


Joe
 

I keep a VOM in my vehicle. Don't need to worry about the meter batteries
going dead when trying to measure car battery voltage when away from home
and it won't start. The analog movement will nicely indicate a weak battery
if the voltage sinks when attempting to start, or is simply too low. DMMs
with a dead battery are useless, DAMHIKT.

Joe

On Thu, Nov 2, 2017 at 2:43 AM, Richard Pope mechanic_2@charter.net
[TekScopes] <TekScopes@yahoogroups.com> wrote:



Hello Dennis,
How are you doing? As I said I still use my Simpson on a regular
basis. Yes, I have a DMM that I use more than a VOM. I wouldn't mind
acquiring a VTVM. They are also highly respected and sought out. Yes you
can null or peak an amplifier with a DMM but it is easier and quicker
with a VOM. A DMM is more accurate measuring resistance especially very
high resistances. You are correct about the VOM still being a useful
tool. As always using the correct tool always makes things easier.
Thanks,
rich!

On 11/2/2017 2:27 AM, 'Dennis Tillman' dennis@ridesoft.com [TekScopes]
wrote:


Hi Jon,

Simpson 260 Meters are extremely well made and they last forever. They
are highly prized by collectors like cameras, fine watches, and even LPs.

There is nothing strange about ohms/volt if you understand the
context. Electro-mechanical meter movements (D'Arsonval/Weston meters
for instance) uses a coil suspended in a magnetic field. A
D'Arsonval/Weston meter movement can be calibrated as a DC voltmeter
if the resistance of the coil is known by calculating the voltage
required to generate a full scale current. To measure more voltage
with the meter movement you add resistance in series with it. When you
do this the basic sensitivity of the meter (measured in ohms/volt)
remains constant.

Analog meters still have their place in electronics since they can be
quicker and easier to read if values are fluctuating quickly. Try
connecting a DVM to a random noise source and you may see what I mean.

I used a VOM for many years in the 1960s and I learned about ohms per
volt at the time. For more than 100 years before I used them analog
meters were the only way to measure electrical quantities. Obviously
it isn't necessary to use VOMs today so there may be no reason to be
familiar with the concepts behind them. Analog meters did make a huge
contribution to getting us where we are today.

The first time I realized you can't do everything with a meter was
when I tried to troubleshoot a flip flop with my VTVM. When I
discovered that a beam of electrons could move a million times faster
than a meter needle I stopped using analog meters and developed a love
for oscilloscopes. I haven't looked back until now. Thanks for
reminding me how strange "ohms per volt" must sound to someone who has
never heard it before.

Dennis Tillman W7PF

On 11/1/2017 11:29 PM, Jon Batters jonbatters32@gmail.com [TekScopes]
wrote:

HI Michael,

Thank you,…..Thank you for your message on VOMs. I had forgotten what
I knew about them.

When Richard Pope wrote about his Simpsons’ and varying input-R, an
alarm bell went off. He didn’t give a model # but I know this is an
old, old company still in business and there’s something funky about
their meters ! Let’s see, Oh I Know; it’s the strange Ohms/ Volt Spec.
Didn’t that die off after WWII ? We should not forget that some of our
members may have been in the Signal Corp in 1939 and that is their
experience base… How OLD is Richard anyway……? ( ha ha ) Maybe This is
what some of our members are referring to re/ varying input-R ! And
they’re correct, for the VOM design ! Anyway, I believe you can still
buy a Simpson ( with a 4” meter movement ) Why you would want to do
this against a modern design, I would enjoy learning. Interestingly,
Fluke brags about their digital display Emulating a bar graph with a
Meter Movement type response for doing Tuning Work !

So…….one of the things I enjoy about our group is that I can post a
message and get responses from around the World. For me this can
be……..you’re an idiot ( not uncommon ) to……I can explain that /
to…….here’s what happened to me / to…..my favorite, Don’t ever……ever
Do “This”…..

Jon Batters, Grants Pass, Or.
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