Curve Tracer vs. Octopus


Rob <rgwood@...>
 

I have a fuzzy memory from back in my electronics days of a circuit called an octopus. More or less involved 6-18Vac transformer, having the scope in X-Y and then observing scope trace/lissajous patterns for various components. If I remember correctly there was even a boutique industry that utilized the same concept in that you could inject AC signal and then measure the pattern at various places in the ckt to troubleshoot the piece of equipment.  Kind of an active troubleshooting mode. The company would publish schematics/tables with the patterns and in this way greatly reduce troubleshooting time and/or fiddling with high voltages and currents….. In any event, not posting to have my memory corrected as it is certain that I am not doing justice and they are 20-30 year old memories….and the mom and pop shop I worked in never purchased same….

 

In any event, I am mostly curious because I have never had the opportunity (or resources) to have a curve tracer. Does or would an octopus serve as a poor man’s curve tracer? I assume (that darn word) that a curve tracer is more of a designers tool than a troubleshooting aid? Is my perception correct? I’m sure it isn’t as cut and dry as I indicate.

 

Biggest thing I am trying to ascertain is…due to cost curve tracer is low on my wish list…. However, given the market price they consistently fetch I am obviously missing something. Mostly looking for insight on what I am missing.. No doubt I could do research myself and likely answer most of my own questions. However, that path would not capture the “in my opinion” factor I have come to respect several associated with this forum for.

 

Thanks as always for the bandwidth

Rob  


Kenneth G. Gordon <kgordon2006@...>
 

On 23 Mar 2013 at 18:50, Rob wrote:

I have a fuzzy memory from back in my electronics days of a circuit called an
octopus.
Not so fuzzy: various versions of it are detailed on the web.

In any event, I am mostly curious because I have never had the opportunity (or
resources) to have a curve tracer. Does or would an octopus serve as a poor man´s
curve tracer?
By all means, yes! In fact, I had access to more than one curve tracer at the University where
I worked until my retirement, and I had built a pretty fancy version of The Octopus for my
shop. I was the Electronic Instrument Specialist, Sr. at the College of Science there.

I MUCH preferred The Octopus for troubleshooting over the curve tracers we had. Once you
got used to them and knew what to watch for, they were very, very much quicker and at least
as accurate.

I assume (that darn word) that a curve tracer is more of a designers
tool than a troubleshooting aid?
Well, I have always viewed them as such. To me, they are too complex to use simply for
trouble-shooting.

BTW, Heathkit sold a unit they named the "Model 2232 Component Tracer" which is nothing
more than a VERY fancy version of The Octopus complete with built-in 'scope.

I have one here which has a "Place of Honor" on my bench. It was given to me by a very,
very good fellow who was closing out a shop somewhere. I am very grateful to him.

Ken Gordon W7EKB


Bob Albert
 

I don't know what an octopus is, but a curve tracer can be simple or complex.  If you want to trace the V-I curve of a component, the unit can be amazingly simple.  But to measure transistors or tubes, you need more than that.

Years ago I built a transistor curve tracer that, when hooked to a 'scope, displayed the family of curves for a transistor.  It included a staircase generator, and various switches and controls but it worked great.  If all you want is a V-I curve of a 2-terminal device, you needn't be that elaborate.

Having said all that, for all the time I ran my retail repair shop (13 years) I never needed it.

Bob


--- On Sat, 3/23/13, Rob wrote:

From: Rob
Subject: [TekScopes] Curve Tracer vs. Octopus
To: TekScopes@...
Date: Saturday, March 23, 2013, 4:50 PM

 

I have a fuzzy memory from back in my electronics days of a circuit called an octopus. More or less involved 6-18Vac transformer, having the scope in X-Y and then observing scope trace/lissajous patterns for various components. If I remember correctly there was even a boutique industry that utilized the same concept in that you could inject AC signal and then measure the pattern at various places in the ckt to troubleshoot the piece of equipment.  Kind of an active troubleshooting mode. The company would publish schematics/tables with the patterns and in this way greatly reduce troubleshooting time and/or fiddling with high voltages and currents….. In any event, not posting to have my memory corrected as it is certain that I am not doing justice and they are 20-30 year old memories….and the mom and pop shop I worked in never purchased same….

 

In any event, I am mostly curious because I have never had the opportunity (or resources) to have a curve tracer. Does or would an octopus serve as a poor man’s curve tracer? I assume (that darn word) that a curve tracer is more of a designers tool than a troubleshooting aid? Is my perception correct? I’m sure it isn’t as cut and dry as I indicate.

 

Biggest thing I am trying to ascertain is…due to cost curve tracer is low on my wish list…. However, given the market price they consistently fetch I am obviously missing something. Mostly looking for insight on what I am missing.. No doubt I could do research myself and likely answer most of my own questions. However, that path would not capture the “in my opinion” factor I have come to respect several associated with this forum for.

 

Thanks as always for the bandwidth

Rob  


Kenneth G. Gordon <kgordon2006@...>
 

On 23 Mar 2013 at 17:17, Bob Albert wrote:

I don't know what an octopus is, but a curve tracer can be simple or
complex.  If you want to trace the V-I curve of a component, the unit
can be amazingly simple.
Bob: The Octopus IS a V-I curve tracer.

  But to measure transistors or tubes, you
need more than that.
It will check bipolar transistors just fine. Tubes are a different matter.

Ken W7EKB


Bob Albert
 

Ken,

I have read, with interest, this discussion of the Octopus.  So I breadboarded one.  After fooling with it for a few minutes I decided not to build it.  I got the usual patterns for open, short, resistor, and diode.  But I doubt I would use it.

Bob


--- On Sat, 3/23/13, Kenneth G. Gordon <kgordon2006@...> wrote:

From: Kenneth G. Gordon
Subject: Re: [TekScopes] Curve Tracer vs. Octopus
To: TekScopes@...
Date: Saturday, March 23, 2013, 7:26 PM

 

On 23 Mar 2013 at 17:17, Bob Albert wrote:

> I don't know what an octopus is, but a curve tracer can be simple or
> complex.  If you want to trace the V-I curve of a component, the unit
> can be amazingly simple.

Bob: The Octopus IS a V-I curve tracer.

>  But to measure transistors or tubes, you
> need more than that.

It will check bipolar transistors just fine. Tubes are a different matter.

Ken W7EKB


Peter Gottlieb <hpnpilot@...>
 

Oh it's very simple. A small transformer and resistor and the scope in X-Y as you say. I used to use (if my memory serves) a little Western Electric 2012B wall wart transformer. Great for two terminal devices like diodes, MOVs and the junctions of bipolar transistors. Will show you the Zener knew nicely too. Won't do the curves for a transistor though, too crude for that, although you can rig stuff up, either static or resistive-divider.

Peter

On 3/23/2013 7:50 PM, Rob wrote:

I have a fuzzy memory from back in my electronics days of a circuit called an octopus. More or less involved 6-18Vac transformer, having the scope in X-Y and then observing scope trace/lissajous patterns for various components. If I remember correctly there was even a boutique industry that utilized the same concept in that you could inject AC signal and then measure the pattern at various places in the ckt to troubleshoot the piece of equipment. Kind of an active troubleshooting mode. The company would publish schematics/tables with the patterns and in this way greatly reduce troubleshooting time and/or fiddling with high voltages and currents�.. In any event, not posting to have my memory corrected as it is certain that I am not doing justice and they are 20-30 year old memories�.and the mom and pop shop I worked in never purchased same�.

In any event, I am mostly curious because I have never had the opportunity (or resources) to have a curve tracer. Does or would an octopus serve as a poor man�s curve tracer? I assume (that darn word) that a curve tracer is more of a designers tool than a troubleshooting aid? Is my perception correct? I�m sure it isn�t as cut and dry as I indicate.

Biggest thing I am trying to ascertain is�due to cost curve tracer is low on my wish list�. However, given the market price they consistently fetch I am obviously missing something. Mostly looking for insight on what I am missing.. No doubt I could do research myself and likely answer most of my own questions. However, that path would not capture the �in my opinion� factor I have come to respect several associated with this forum for.

Thanks as always for the bandwidth

Rob

--------------------------------------------------------------------------------

No virus found in this message.
Checked by AVG - www.avg.com <http://www.avg.com>
Version: 10.0.1430 / Virus Database: 2641/5698 - Release Date: 03/23/13


 

I just use the sine or triangle output of a function generator. Most
will supply at least +/- 10 volts at 100 milliamps.

On Sat, 23 Mar 2013 23:18:11 -0400, Peter Gottlieb
<hpnpilot@verizon.net> wrote:

Oh it's very simple. A small transformer and resistor and the scope in X-Y as
you say. I used to use (if my memory serves) a little Western Electric 2012B
wall wart transformer. Great for two terminal devices like diodes, MOVs and the
junctions of bipolar transistors. Will show you the Zener knew nicely too. Won't
do the curves for a transistor though, too crude for that, although you can rig
stuff up, either static or resistive-divider.

Peter


Rob <rgwood@...>
 

Thank you all who have replied so far. The ckt at the following link aligns pretty well with my memory.

http://www.smcelectronics.com/CIRCUITS/OCTOPUS.PDF

I should have thought about that before I posted my initial question/s. As a 1000 words is worth a picture. Always better to talk from a picture.

 

Even with the picture I have some disconnect. It does seem like the one we had at the shop (way back then) had the capability of switching a few passive components in or out of Ckt. If I recall correctly we used it to look at oscillators and could switch capacitors in or out?? The whole apparatus was the brain child of one of the senior technicians so he more or less taught me how to utilize it…If I recall correctly it had great utility in trouble shooting consumer audio equipment. (70’s -80’s amplifiers--- push, pull)

 

. Anyway, again my inquiry isn’t so much to reconnect my grey matter or take a nostalgic trip. I am looking to see if it would be worth pursuing making something up as part of my bench “bag of tricks” and perhaps learn something along the way. The answers so far seem to indicate that it would indeed have utility. If nothing else it will make pretty scope pictures and I can tinker with some components, etc. and deepen my Oscilloscope skills and ckt/component knowledge.

 

If it would not take to much more bandwidth (or give someone a stomach ache).  In layman’s terms; why does the octopus have no utility for vacuum tubes? It is obvious to me that there is no allowance for filament voltage in the ckt above. However, if one supplied that via a different source/transformer could the octopus then be utilized? Even I realize this last questions is drifting the inquiry out of bounds for forum topic. So perhaps it is best I leave that last question as rhetorical and I will research myself. On the other hand a note off forum pointing me in the correct direction would be appreciated.

 

Thanks as always, I gain a lot form these thought experiments.  

Rob    

 

 

From: TekScopes@... [mailto:TekScopes@...] On Behalf Of Kenneth G. Gordon
Sent: Saturday, March 23, 2013 9:26 PM
To: TekScopes@...
Subject: Re: [TekScopes] Curve Tracer vs. Octopus

 

 

On 23 Mar 2013 at 17:17, Bob Albert wrote:

> I don't know what an octopus is, but a curve tracer can be simple or
> complex.  If you want to trace the V-I curve of a component, the unit
> can be amazingly simple.

Bob: The Octopus IS a V-I curve tracer.

>  But to measure transistors or tubes, you
> need more than that.

It will check bipolar transistors just fine. Tubes are a different matter.

Ken W7EKB


Peter Gottlieb <hpnpilot@...>
 

Well, yeah, voltage. Vacuum tubes need a lot more. I think I figured this trick out in about 1970 shortly after I built my first major kit, an Eico scope. As I mentioned I used a higher voltage. The schematic shown puts out a very low (and circuit safe) voltage but you're not going to see that Zener knee they show as one of the patterns as very few if any Zeners go that low in voltage. For tubes you'd want higher voltage and less current, and don't touch the probes! You'd also want a bias supply for the grid.

On 3/24/2013 12:07 AM, Rob wrote:

Thank you all who have replied so far. The ckt at the following link aligns pretty well with my memory.

http://www.smcelectronics.com/CIRCUITS/OCTOPUS.PDF

I should have thought about that before I posted my initial question/s. As a 1000 words is worth a picture. Always better to talk from a picture.

Even with the picture I have some disconnect. It does seem like the one we had at the shop (way back then) had the capability of switching a few passive components in or out of Ckt. If I recall correctly we used it to look at oscillators and could switch capacitors in or out?? The whole apparatus was the brain child of one of the senior technicians so he more or less taught me how to utilize it�If I recall correctly it had great utility in trouble shooting consumer audio equipment. (70�s -80�s amplifiers--- push, pull)

. Anyway, again my inquiry isn�t so much to reconnect my grey matter or take a nostalgic trip I am looking to see if it would be worth pursuing making something up as part of my bench �bag of tricks� and perhaps learn something along the way. The answers so far seem to indicate that it would indeed have utility. If nothing else it will make pretty scope pictures and I can tinker with some components, etc. and deepen my Oscilloscope skills and ckt/component knowledge.

If it would not take to much more bandwidth (or give someone a stomach ache). In layman�s terms; why does the octopus have no utility for vacuum tubes? It is obvious to me that there is no allowance for filament voltage in the ckt above. However, if one supplied that via a different source/transformer could the octopus then be utilized? Even I realize this last questions is drifting the inquiry out of bounds for forum topic. So perhaps it is best I leave that last question as rhetorical and I will research myself. On the other hand a note off forum pointing me in the correct direction would be appreciated.

Thanks as always, I gain a lot form these thought experiments.

Rob

*From:*TekScopes@yahoogroups.com [mailto:TekScopes@yahoogroups.com] *On Behalf Of *Kenneth G. Gordon
*Sent:* Saturday, March 23, 2013 9:26 PM
*To:* TekScopes@yahoogroups.com
*Subject:* Re: [TekScopes] Curve Tracer vs. Octopus

On 23 Mar 2013 at 17:17, Bob Albert wrote:

I don't know what an octopus is, but a curve tracer can be simple or
complex. If you want to trace the V-I curve of a component, the unit
can be amazingly simple.
Bob: The Octopus IS a V-I curve tracer.

But to measure transistors or tubes, you
need more than that.
It will check bipolar transistors just fine. Tubes are a different matter.

Ken W7EKB

--------------------------------------------------------------------------------

No virus found in this message.
Checked by AVG - www.avg.com <http://www.avg.com>
Version: 10.0.1430 / Virus Database: 2641/5698 - Release Date: 03/23/13


PA4TIM
 

A curvetracer is a Landrover ( sorry, i'm adicted to them, but for you in the US, a hummer)) a octopus is a wheelchair ;-) the curvetracer is versatile and can to everything, the octopus is a simple aid. Like a hummer you only need a curvetracer when you go beyond the normal stuff, a octopus is an aid to compensate the knowledge of decent use of a multimeter/scoope like the wheelchair is or those who can not walk ( do not take this to serious but it is about the difference, the octopus is a handy tool and i still use my VU-data hurton copy now and then when i can not power up the patient)

The CT has has so much more al only much more Voltage/ currenct capabitily that I do not know where to start. Tektronix has a nice book in the concept range about curvetracing. The octopus is more like a simplified version of the hurton tracker.

I builded an octopus, added a Vb posabillity to it. Then i bought the VU-data. Then i have builded a simple curvetracer that could make something like 6 traces. Later i replaced it with a 577 that after 2 years is replaced by 576

I have done the strangest things with it. Use it as an octopus, matched chopper neonlamps with it, measured ESR, capacitance, ( did not found out a way to measure DC leakage yet)  charged and zapped batteries, tested zeners, matched transistors, examined Vf versus current and also versus temp from diodes until they died. Measured Tempco of resistors. Tested voltage regulators.Found strange failures of tranistors that must be bad from scope and volt measurements but that looked good on a hurton and simple multimter diodetest. Even the peak componnt tester said they were OK, the 576 showed the true nature of failure. And then I probably forget a lot other fun stuff. I also made a tube adapter but still have not finnished that because i found a Weston Tubetester. And I am thinking about making a simple tester go/no for opams but probably a separeret tester would be more easy. 

Fred PA4TIM

Op 24 mrt. 2013 om 04:35 heeft David <davidwhess@...> het volgende geschreven:

 

I just use the sine or triangle output of a function generator. Most
will supply at least +/- 10 volts at 100 milliamps.

On Sat, 23 Mar 2013 23:18:11 -0400, Peter Gottlieb
<hpnpilot@...> wrote:

>Oh it's very simple. A small transformer and resistor and the scope in X-Y as
>you say. I used to use (if my memory serves) a little Western Electric 2012B
>wall wart transformer. Great for two terminal devices like diodes, MOVs and the
>junctions of bipolar transistors. Will show you the Zener knew nicely too. Won't
>do the curves for a transistor though, too crude for that, although you can rig
>stuff up, either static or resistive-divider.
>
>Peter


Bert Haskins
 

On 03/23/2013 11:35 PM, David wrote:
 

I just use the sine or triangle output of a function generator. Most
will supply at least +/- 10 volts at 100 milliamps.

Yep, then add a very simple step generator and you have
a pretty good low level curve tracer.


On Sat, 23 Mar 2013 23:18:11 -0400, Peter Gottlieb
<hpnpilot@...> wrote:

>Oh it's very simple. A small transformer and resistor and the scope in X-Y as
>you say. I used to use (if my memory serves) a little Western Electric 2012B
>wall wart transformer. Great for two terminal devices like diodes, MOVs and the
>junctions of bipolar transistors. Will show you the Zener knew nicely too. Won't
>do the curves for a transistor though, too crude for that, although you can rig
>stuff up, either static or resistive-divider.
>
>Peter



Bert Haskins
 

On 03/24/2013 12:07 AM, Rob wrote:
 

Thank you all who have replied so far. The ckt at the following link aligns pretty well with my memory.

http://www.smcelectronics.com/CIRCUITS/OCTOPUS.PDF

I should have thought about that before I posted my initial question/s. As a 1000 words is worth a picture. Always better to talk from a picture.

 

Even with the picture I have some disconnect. It does seem like the one we had at the shop (way back then) had the capability of switching a few passive components in or out of Ckt. If I recall correctly we used it to look at oscillators and could switch capacitors in or out?? The whole apparatus was the brain child of one of the senior technicians so he more or less taught me how to utilize it…If I recall correctly it had great utility in trouble shooting consumer audio equipment. (70’s -80’s amplifiers--- push, pull)

 

. Anyway, again my inquiry isn’t so much to reconnect my grey matter or take a nostalgic trip. I am looking to see if it would be worth pursuing making something up as part of my bench “bag of tricks” and perhaps learn something along the way. The answers so far seem to indicate that it would indeed have utility. If nothing else it will make pretty scope pictures and I can tinker with some components, etc. and deepen my Oscilloscope skills and ckt/component knowledge.

 

If it would not take to much more bandwidth (or give someone a stomach ache).  In layman’s terms; why does the octopus have no utility for vacuum tubes? It is obvious to me that there is no allowance for filament voltage in the ckt above. However, if one supplied that via a different source/transformer could the octopus then be utilized? Even I realize this last questions is drifting the inquiry out of bounds for forum topic. So perhaps it is best I leave that last question as rhetorical and I will research myself. On the other hand a note off forum pointing me in the correct direction would be appreciated.

 

Thanks as always, I gain a lot form these thought experiments.  

Rob    

 

 

From: TekScopes@... [mailto:TekScopes@...] On Behalf Of Kenneth G. Gordon
Sent: Saturday, March 23, 2013 9:26 PM
To: TekScopes@...
Subject: Re: [TekScopes] Curve Tracer vs. Octopus

 

 

On 23 Mar 2013 at 17:17, Bob Albert wrote:

> I don't know what an octopus is, but a curve tracer can be simple or
> complex.  If you want to trace the V-I curve of a component, the unit
> can be amazingly simple.

Bob: The Octopus IS a V-I curve tracer.

>  But to measure transistors or tubes, you
> need more than that.

It will check bipolar transistors just fine. Tubes are a different matter.

Ken W7EKB



w2aew
 

I did a video on the Octopus several months ago, and it has proven to be one my most-watched videos.
http://www.youtube.com/watch?v=Gwo3pEH7hUE

Alan

--- In TekScopes@yahoogroups.com, "Rob" <rgwood@...> wrote:

I have a fuzzy memory from back in my electronics days of a circuit called
an octopus. More or less involved 6-18Vac transformer, having the scope in
X-Y and then observing scope trace/lissajous patterns for various
components. If I remember correctly there was even a boutique industry that
utilized the same concept in that you could inject AC signal and then
measure the pattern at various places in the ckt to troubleshoot the piece
of equipment. Kind of an active troubleshooting mode. The company would
publish schematics/tables with the patterns and in this way greatly reduce
troubleshooting time and/or fiddling with high voltages and currents... In
any event, not posting to have my memory corrected as it is certain that I
am not doing justice and they are 20-30 year old memories..and the mom and
pop shop I worked in never purchased same..



In any event, I am mostly curious because I have never had the opportunity
(or resources) to have a curve tracer. Does or would an octopus serve as a
poor man's curve tracer? I assume (that darn word) that a curve tracer is
more of a designers tool than a troubleshooting aid? Is my perception
correct? I'm sure it isn't as cut and dry as I indicate.



Biggest thing I am trying to ascertain is.due to cost curve tracer is low on
my wish list.. However, given the market price they consistently fetch I am
obviously missing something. Mostly looking for insight on what I am
missing.. No doubt I could do research myself and likely answer most of my
own questions. However, that path would not capture the "in my opinion"
factor I have come to respect several associated with this forum for.



Thanks as always for the bandwidth

Rob


Rob <rgwood@...>
 

The video is great. Thank you.

In fact, I have watched quite a few of your videos.

I never took the time to Thank you for those.

So… Thank you for those. (and the reply to this).

Rob

 

 

From: TekScopes@... [mailto:TekScopes@...] On Behalf Of w2aew
Sent: Sunday, March 24, 2013 7:52 AM
To: TekScopes@...
Subject: [TekScopes] Re: Curve Tracer vs. Octopus

 

 

I did a video on the Octopus several months ago, and it has proven to be one my most-watched videos.
http://www.youtube.com/watch?v=Gwo3pEH7hUE

Alan



Ed Breya
 

Sorry Fred, but I couldn't let the Landrover comment go unchecked. (OT) I had a brand-new 1999 Discovery II - the most unreliable vehicle I've ever owned, and that says a lot, considering some of my past cars. The dealer was very nice about the many repairs until the warranty expired. I traded it in (worth only one-quarter of its original price) toward a 2004 Caddy Escalade, which has become my favorite vehicle of all time - twice the power, bigger, with better gas mileage, nicer ride, and few problems, even after the warranty expired.

Back to topic: Yes, it's nice to have a "real" curve tracer (I consider them essential), but a simple X-Y CT box attached to a scope can take care of most common diagnostic issues and parts testing. I have three real CTs, but seldom test in three-terminal device modes - usually X-Y tells me enough. A real CT of course can do much more, and has a large dynamic range, but a simple home-made rig can go a long way, and can be modified and improved by the the user/builder as needs change. For anyone rolling their own, I'd recommend starting simple, with an oversized chassis, and then add on if needed.

Ed

--- In TekScopes@yahoogroups.com, Pa4tim <fredschneider@...> wrote:

A curvetracer is a Landrover ( sorry, i'm adicted to them, but for you in the US, a hummer)) a octopus is a wheelchair ;-) the curvetracer is versatile and can to everything, the octopus is a simple aid. Like a hummer you only need a curvetracer when you go beyond the normal stuff, a octopus is an aid to compensate the knowledge of decent use of a multimeter/scoope like the wheelchair is or those who can not walk ( do not take this to serious but it is about the difference, the octopus is a handy tool and i still use my VU-data hurton copy now and then when i can not power up the patient)

The CT has has so much more al only much more Voltage/ currenct capabitily that I do not know where to start. Tektronix has a nice book in the concept range about curvetracing. The octopus is more like a simplified version of the hurton tracker.

I builded an octopus, added a Vb posabillity to it. Then i bought the VU-data. Then i have builded a simple curvetracer that could make something like 6 traces. Later i replaced it with a 577 that after 2 years is replaced by 576

I have done the strangest things with it. Use it as an octopus, matched chopper neonlamps with it, measured ESR, capacitance, ( did not found out a way to measure DC leakage yet) charged and zapped batteries, tested zeners, matched transistors, examined Vf versus current and also versus temp from diodes until they died. Measured Tempco of resistors. Tested voltage regulators.Found strange failures of tranistors that must be bad from scope and volt measurements but that looked good on a hurton and simple multimter diodetest. Even the peak componnt tester said they were OK, the 576 showed the true nature of failure. And then I probably forget a lot other fun stuff. I also made a tube adapter but still have not finnished that because i found a Weston Tubetester. And I am thinking about making a simple tester go/no for opams but probably a separeret tester would be more easy.

Fred PA4TIM

Op 24 mrt. 2013 om 04:35 heeft David <davidwhess@...> het volgende geschreven:

I just use the sine or triangle output of a function generator. Most
will supply at least +/- 10 volts at 100 milliamps.

On Sat, 23 Mar 2013 23:18:11 -0400, Peter Gottlieb
<hpnpilot@...> wrote:

Oh it's very simple. A small transformer and resistor and the scope in X-Y as
you say. I used to use (if my memory serves) a little Western Electric 2012B
wall wart transformer. Great for two terminal devices like diodes, MOVs and the
junctions of bipolar transistors. Will show you the Zener knew nicely too. Won't
do the curves for a transistor though, too crude for that, although you can rig
stuff up, either static or resistive-divider.

Peter


J. D. Leach
 

On Sunday 24 March 2013 08:51 am, w2aew wrote:
I did a video on the Octopus several months ago, and it has proven to be
one my most-watched videos. http://www.youtube.com/watch?v=Gwo3pEH7hUE

Alan
I rarely post here, but had to on this subject.

Alan, that was a very good video. Well explained, and informative. I am sure
you were a hit with your "Scopes for Dopes" classes.

I built an octopus some years back, but had less than sterling results due to
the primitive scope I was using, a 1942 Clough-Brengle Graphoscope. In the
past two years, I have accumulated a pile of Tek gear, and a 564B Mod 121N.
Have wanted to play with the octopus using the 564, but could not as I did
not have the plug-ins necessary for X-Y display (a 3A1 amp and a 3B3 time
base). This past month, I snagged a pair of 3A72 amps that surprisingly, had
all their tubes and worked (after a fashion) from that large online auction
site. Spent a couple hours cleaning and lubricating all the switches and
controls last week, and will calibrate them tonight.

The first thing I will do with the '72s, is drag my octopus from the shelf and
see what it will really do.

--
J. D.


Robert Simpson
 

This diode tracer is what I used to help find a bad diode in my 485 (photo folder 485 no trace).
Bob

--- In TekScopes@yahoogroups.com, Peter Gottlieb <hpnpilot@...> wrote:

Oh it's very simple. A small transformer and resistor and the scope in X-Y as
you say. I used to use (if my memory serves) a little Western Electric 2012B
wall wart transformer. Great for two terminal devices like diodes, MOVs and the
junctions of bipolar transistors. Will show you the Zener knew nicely too. Won't
do the curves for a transistor though, too crude for that, although you can rig
stuff up, either static or resistive-divider.

Peter


On 3/23/2013 7:50 PM, Rob wrote:

I have a fuzzy memory from back in my electronics days of a circuit called an
octopus. More or less involved 6-18Vac transformer, having the scope in X-Y
and then observing scope trace/lissajous patterns for various components. If I
remember correctly there was even a boutique industry that utilized the same
concept in that you could inject AC signal and then measure the pattern at
various places in the ckt to troubleshoot the piece of equipment. Kind of an
active troubleshooting mode. The company would publish schematics/tables with
the patterns and in this way greatly reduce troubleshooting time and/or
fiddling with high voltages and currents….. In any event, not posting to have
my memory corrected as it is certain that I am not doing justice and they are
20-30 year old memories….and the mom and pop shop I worked in never purchased
same….

In any event, I am mostly curious because I have never had the opportunity (or
resources) to have a curve tracer. Does or would an octopus serve as a poor
man's curve tracer? I assume (that darn word) that a curve tracer is more of a
designers tool than a troubleshooting aid? Is my perception correct? I'm sure
it isn't as cut and dry as I indicate.

Biggest thing I am trying to ascertain is…due to cost curve tracer is low on
my wish list…. However, given the market price they consistently fetch I am
obviously missing something. Mostly looking for insight on what I am missing..
No doubt I could do research myself and likely answer most of my own
questions. However, that path would not capture the "in my opinion" factor I
have come to respect several associated with this forum for.

Thanks as always for the bandwidth

Rob


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magnustoelle
 

Good Day, Rob,

I totally agree here - such a component tester is a simple, yet very effective little helper. I have built one myself last summer and would not want to miss it.
Side note: This was the first DIY-project where the housing came first (a left-over) and I wanted to do sth. useful with it.

Some more suggestions for overly simple modifications:

- If you add a rotary switch and a few selected resistors to allow various output current levels, you can make the device even more useful.
- A switchable diode allows to test with (rectified or pulsed) DC.
- A BNC jack and yet another switch allows the use of an external generator instead of AC line signal through a transformer.
You would need to float the external generator, though; as to avoid ground issues. Or you may use a nice small audio transformer and a double-pole switch to isolate the external generator.

The schematics are so simple, that I better save everybody's time by not posting them...

I have added a few pictures to the Photos Section, folder name is "DIY component tester":http://groups.yahoo.com/group/TekScopes/photos/album/1220275392/pic/list

Just build one as to enjoy it.

Alan, that is a nice video you have created - thank you.

Cheers,

Magnus


stefan_trethan
 

I am very afraid to build such a tester, if you look in the dictionary
under "feature creep" there is a photo of one with connectors and
knobs sticking out every which way.
It would never be finished.

ST

On Tue, Mar 26, 2013 at 1:17 PM, magnustoelle <magnustoelle@yahoo.com> wrote:


Good Day, Rob,

I totally agree here - such a component tester is a simple, yet very effective little helper. I have built one myself last summer and would not want to miss it.
Side note: This was the first DIY-project where the housing came first (a left-over) and I wanted to do sth. useful with it.

Some more suggestions for overly simple modifications:

- If you add a rotary switch and a few selected resistors to allow various output current levels, you can make the device even more useful.
- A switchable diode allows to test with (rectified or pulsed) DC.
- A BNC jack and yet another switch allows the use of an external generator instead of AC line signal through a transformer.
You would need to float the external generator, though; as to avoid ground issues. Or you may use a nice small audio transformer and a double-pole switch to isolate the external generator.

The schematics are so simple, that I better save everybody's time by not posting them...

I have added a few pictures to the Photos Section, folder name is "DIY component tester":http://groups.yahoo.com/group/TekScopes/photos/album/1220275392/pic/list

Just build one as to enjoy it.

Alan, that is a nice video you have created - thank you.

Cheers,

Magnus


Rob <rgwood@...>
 

Thank you Magnus. If it wouldn’t be asking too much please do send me schematics or any other hard copy you may have made (E-mail or a link or I can send you a public address to my Drop box account)).

 

I get the jest of what your saying and have decided I am going to make something. I am tinkering with the idea of enclosing it in a TM-500 or 7000 series Scope box maybe feed it off of one of Johns extender cards or something.….not sure  what at this juncture….just brain candy…(hence the public reply kind of soliciting ideas.).

 

Anyway, I’d like your ideas as reference and I may modify somewhat, etc. It would save me the math and I am no designer…. just having the thought of tying the two ideas together is at the edge of my skill set… little alone actually… well you get the idea…

 

If I do ultimately make something; there will be a lot of interaction via this forum it is certain

 

Thanks as always for the bandwidth.

Rob

 

From: TekScopes@... [mailto:TekScopes@...] On Behalf Of magnustoelle
Sent: Tuesday, March 26, 2013 7:17 AM
To: TekScopes@...
Subject: [TekScopes] Re: Curve Tracer vs. Octopus

 

 



Good Day, Rob,

I totally agree here - such a component tester is a simple, yet very effective little helper. I have built one myself last summer and would not want to miss it.
Side note: This was the first DIY-project where the housing came first (a left-over) and I wanted to do sth. useful with it.

Some more suggestions for overly simple modifications:

- If you add a rotary switch and a few selected resistors to allow various output current levels, you can make the device even more useful.
- A switchable diode allows to test with (rectified or pulsed) DC.
- A BNC jack and yet another switch allows the use of an external generator instead of AC line signal through a transformer.
You would need to float the external generator, though; as to avoid ground issues. Or you may use a nice small audio transformer and a double-pole switch to isolate the external generator.

The schematics are so simple, that I better save everybody's time by not posting them...

I have added a few pictures to the Photos Section, folder name is "DIY component tester":http://groups.yahoo.com/group/TekScopes/photos/album/1220275392/pic/list

Just build one as to enjoy it.

Alan, that is a nice video you have created - thank you.

Cheers,

Magnus