Author Topic: Curve tracer , octopus ?  (Read 13416 times)

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Offline KD0CAC John

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Curve tracer , octopus ?
« on: September 20, 2012, 11:53:40 pm »
I picked this up at a ham fest , it would seem to be a curve tracer / octopus built for an old Echo 460 scope , it has bana plugs for scope connections .
I plugged into 120 AC , then measured both sides of the transformer , AC wall outlet goes through a coil wound resistor and steps down the voltage to 60v then goes into transformer , coming out measured 18v .
Its labeled as a transistor tester [ home-brewed ] .
Some of my questions are , as I have checked on internet lately , most seem to be for modern testing lower voltages , maybe down to 6v , assuming there is an issue with more modern components running lower voltages ?
Then the bana plugs , changing to shielded BNC ?
Also most of the info I gathered on internet showed that units like this would give pattern for testing caps also ?
Thanks
John
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Offline M0BSW

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Re: Curve tracer , octopus ?
« Reply #1 on: September 21, 2012, 12:32:16 am »
A brilliant device, go on you tube , W2AEW,Alan who is also on here, I built his version ,on my profile picture it's the second box from the top grey one, if you watch  Alans video you can see exactly what they do, we run 240 volts over here in the UK , so my transformer is 240/6.3v works just fine. Link below
Paul

« Last Edit: September 21, 2012, 12:49:05 am by M0BSW »
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Offline M0BSW

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Re: Curve tracer , octopus ?
« Reply #2 on: September 21, 2012, 12:39:02 am »
I'm a great fan of Alan, he does a lot of really good videos that explain things just perfectly,  here's another really good link to Alan's videos
http://www.youtube.com/user/w2aew?feature=results_main
« Last Edit: September 21, 2012, 12:47:03 am by M0BSW »
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Offline w2aew

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Re: Curve tracer , octopus ?
« Reply #3 on: September 21, 2012, 04:38:00 am »
I'm a great fan of Alan, he does a lot of really good videos that explain things just perfectly,  here's another really good link to Alan's videos
http://www.youtube.com/user/w2aew?feature=results_main

Thanks for the flowers, Paul!
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Offline M0BSW

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Re: Curve tracer , octopus ?
« Reply #4 on: September 21, 2012, 04:49:26 am »
No Problem Alan others should be made aware of these brilliant videos, they help me no end.
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Offline KD0CAC John

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Re: Curve tracer , octopus ?
« Reply #5 on: September 21, 2012, 06:47:18 am »
I forgot to post the pictures .
I will check out the video , thanks .
Still hope to see some answers to the questions ?
John
 

Offline JoannaK

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Re: Curve tracer , octopus ?
« Reply #6 on: September 21, 2012, 08:09:19 am »

Using shielded bnc:s is quite overkill (or going with lillies) for such low frequency device (60/120hz) , but if you like those connector better (IMHO BNC is a bit PITA) than silmple banana blugs it's for you to hack.

For the voltage.. I think It's related the maximum current(wattage) the octopus pushed trough component. I tend to thing that -+6V could be safer though..  I would not go bellow 3 volts, cause high voltage needs of white leds.. 
 

Offline KD0CAC John

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Re: Curve tracer , octopus ?
« Reply #7 on: September 22, 2012, 12:07:57 am »
My main reason for going to BNC is because of the connection to scope .
I do not get you voltage reply , " I would not go bellow 3 volts , cause high voltage needs of white leds.. "
Thanks



 

Offline M0BSW

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Re: Curve tracer , octopus ?
« Reply #8 on: September 22, 2012, 03:54:12 am »
This is my version, everything I build is boxed and finished,no revisits.
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Offline TriodeTiger

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Re: Curve tracer , octopus ?
« Reply #9 on: September 22, 2012, 06:36:35 am »
Can I just use a sine wave oscillator (referenced to earth?) (edit: the xformer wouldn't be, so nevermind) instead of a transformer for this? I've one roughly available, not completely comfortable with rigging a transformer yet, although I do have heatshrink and a suitable case available.

Alexander.
« Last Edit: September 22, 2012, 06:41:27 am by MmCoffee »
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Offline w2aew

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Re: Curve tracer , octopus ?
« Reply #10 on: September 22, 2012, 11:37:58 am »
Can I just use a sine wave oscillator (referenced to earth?) (edit: the xformer wouldn't be, so nevermind) instead of a transformer for this? I've one roughly available, not completely comfortable with rigging a transformer yet, although I do have heatshrink and a suitable case available.

Alexander.

Yes, you can. In fact, that's what I did in the video.  Function generator into a transformer, then built the octopus on the secondary side of the transformer. I believe I used an ld 12v transformer in the reverse direction (drove the 12v side with a few hundred mV).
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Offline vk6zgo

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Re: Curve tracer , octopus ?
« Reply #11 on: September 22, 2012, 03:35:16 pm »
Just spent about an hour,playing with one of these.
Used a 12V AC wall wart,a couple of probes,& away I went.
The 7613 doesn't have a  XY switch pos,but the 7B53A plug in has a divide by 10 input position on its X input so I can get it to not overscan horizontally.
Worked OK,but next time I will use one channel for Horiz with a jumper from the vert out to the EXT input on the 7B53A.
Not sure that I would use it much,but maybe I should build one into a spare box.
 

Offline mianchen

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Re: Curve tracer , octopus ?
« Reply #12 on: September 22, 2012, 05:29:40 pm »
I've built one following Allan's video, but then I realised that my newly acquired HM504 has a component tester function that does the exact same thing. However I found this one (http://www.changpuak.ch/electronics/Curve_Tracer_advanced.php) the other day and I think it's quite a nice design (what do I know?), may build one later.





I like to generate graphs like this :) they look pretty! Prettier if they're on an analogue scope :)


 

Offline M0BSW

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Re: Curve tracer , octopus ?
« Reply #13 on: September 22, 2012, 09:35:04 pm »
 Now see what youv'e done , I'm now going to have to build one :))))))))))))
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Offline SeanB

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Re: Curve tracer , octopus ?
« Reply #14 on: September 22, 2012, 11:34:00 pm »
On my list too, and i even have a scope frame to put it in. It was some medical instrument on auction, dead med side, but the Tektronix scope on the display side is perfect, though it only has XY and Z inputs at millivolt levels to use.
 

Offline T4P

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Re: Curve tracer , octopus ?
« Reply #15 on: September 23, 2012, 03:14:13 am »
Looks interesting  :) Gonna have to build one by the end of the year, thanks MC
 

Offline TriodeTiger

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Re: Curve tracer , octopus ?
« Reply #16 on: September 23, 2012, 11:18:59 am »
Had to improvise for sine reference. I used audacity to generate a 1kHz tone rather than 60Hz for my audio transformer, and got a 20Vp-p signal out of it...loaded it went to nothing.

So I rigged two 9Vs for split supply,  used 10kHz (amplitude dropped to ~<9Vp-p) and just used a spare UA741CN op amp as a voltage follower...and... Success!

Germanium and red LED in antiparallel:


1uF cap:

Bit hackier than Alan's...

Code: [Select]
         470
AC-----/\/\/\------+----o Scope X
                   |       
                   o
                   +
                  DUT
                   -
                   o
         10        |
0V-+---/\/\/\------+----o Scope Ground
   |
   +--------------------o Scope Y
(inspired by http://www.repairfaq.org/sam/semitest.htm#stqdc due to others looking confusing in my tired state :-)

Which works, but I need to figure what on earth the divisions are mA/cm and V/cm wise. My homework. I made this post because when I first saw an octopus circuit somewhere it excited me, now I have one :-)

Alexander. PS: I sure do edit posts a lot.
« Last Edit: September 23, 2012, 03:55:29 pm by MmCoffee »
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Offline JoannaK

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Re: Curve tracer , octopus ?
« Reply #17 on: September 23, 2012, 01:34:40 pm »
My main reason for going to BNC is because of the connection to scope .
I do not get you voltage reply , " I would not go bellow 3 volts , cause high voltage needs of white leds.. "
Thanks

Sorry: English not native..

What I was trying to say was;  Semiconductor diode has forward voltage (Vf) that depends on diode type/material. As long as the test voltage is bellow this threshold, there's no current flowing trough. Thus to see the typical diode curve (and to verify part) you'll need to test diodes with somewhat higher voltage.

For example .. see this basic diode type (1N4448) http://www.fairchildsemi.com/ds/1N/1N914.pdf
At page 2 you can look for Vf and it's around 700 milli Volts, vallue quite typical for silicon diodes.

While on white 5W Cree led http://www.cree.com/~/media/Files/Cree/LED%20Components%20and%20Modules/HB/Data%20Sheets/C503B%20WAN%20876.pdf  Vf is typically 3.2 Volts but may well be higher depending of the part.


 

Offline Sigmoid

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Re: Curve tracer , octopus ?
« Reply #18 on: August 15, 2013, 01:20:49 am »
Seems lovely, I want to build one... But then I noticed that they don't have a Gerber package posted, just a proprietary project format! And it's only for Windows! FAIL! :( I'm a Mac and Linux guy!

So if someone with the software installed could generate and post the industry standard manufacturing files online, I'd be eternally grateful... Or if others want to build this thing, we could just order one batch of PCBs, those can be sent via plain letter post for cheap. :)

I've built one following Allan's video, but then I realised that my newly acquired HM504 has a component tester function that does the exact same thing. However I found this one (http://www.changpuak.ch/electronics/Curve_Tracer_advanced.php) the other day and I think it's quite a nice design (what do I know?), may build one later.





I like to generate graphs like this :) they look pretty! Prettier if they're on an analogue scope :)



 

Online kripton2035

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Re: Curve tracer , octopus ?
« Reply #19 on: August 15, 2013, 01:31:50 am »
it's made with the target 3001 software

Offline M0BSW

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Re: Curve tracer , octopus ?
« Reply #20 on: August 15, 2013, 02:11:35 am »
it's made with the target 3001 software
Ahhh kripton I see on today's News your beautiful country is out of recession now, not sure about us in the uk or ist it Poland-uk now, anyway really pleased for you over there.
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Online kripton2035

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Re: Curve tracer , octopus ?
« Reply #21 on: August 15, 2013, 04:02:36 am »
3 months ago our dear government didnt knowwhy the crisis was still not finished
and today they didnt notice the recession is over...
well with 0.5% better I would not bet that we will not be still in recession next month !

Offline Sigmoid

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Re: Curve tracer , octopus ?
« Reply #22 on: August 15, 2013, 11:27:52 am »
Yea, Europe is officially f**ed. XD

But returning to the question, anyone want to build one of these giant octopuses on the East Coast? It would be highly beneficial to order the PCBs together. Maybe cases too.
 

Offline KD0CAC John

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Re: Curve tracer , octopus ?
« Reply #23 on: August 15, 2013, 10:09:58 pm »
I want to play :)
I would be up for buying in .
I have one from a older ham radio guy that used higher voltage , I would assume because most tube gear back then , about 16 volts .
I'm also a ham radio operator .
 


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