SUPERMAGOO

tube curve tracer doubt
« on: September 04, 2009, 08:32:02 AM »
hi.
I'm thinking of buying a curve tracer and found this link: http://www.haglabs.com/vacutrace.html
anyone know if it works well?
any recommendation will be welcome.

greetings.
cristian.
« Last Edit: September 05, 2009, 08:46:32 AM by SUPERMAGOO »


Sredna

Re: curve tracer doubt
« Reply #1 on: September 04, 2009, 09:54:42 AM »
Are you looking for a curve tracer in general or do you need a tube curve tracer?

For a normal curve tracer you can find a Huntron Tracker pretty cheap on eBay...

The Vacutrace seams very nich thou...
Hmm... in which direction do the electrons actually go?

analag

Re: curve tracer doubt
« Reply #2 on: September 04, 2009, 12:49:05 PM »
How about a 577?
Audio engineering suffers from misinformation, disinformation, and downright lying more than most fields of endeavour.

1954U1

Re: curve tracer doubt
« Reply #3 on: September 04, 2009, 12:52:39 PM »
Also search for Heathkit 1121 or 3121, they goes to 200V 200mA [1A at 40V] and have the voltage-FET feature [but only to -9V],
so you only need a supply for the heathers [and for the screens if you want to trace pentodes] and 2 amps if you want more power and volts.

Or, you can buy a superbulky Tek 577, which goes to 1600V
[0.6A at 100V, 0.15A at 400V, 0.04A at 1600V, double the Amperes if you use the pulsed current option], or a 575 with the option for hi voltage,
and add the heathers&screens supply [for the 575, you must also add a resistor to convert current in voltage, because it dont have the FET option like the 577].

You can find the Heathkit on ebay for around 90 USD, the Tek 577 [not calibrated and probably with some work required] for around 250-300 USD.
The 575 is less costly.
The 577 give you grid voltage only to -40V, but you can bias the starting voltage so you can have more.

I use both the 577 and the 1121.
The Heathkit is nice and small, the 577 is a huge heavy beast.

If you want, I have the complete building manual of the Heathkit, and the service&operator manuals of the Tek 577.
[the 575 is on bama web site].

A nice thing of the Vacutrace is that on the manual you have the complete schematic.


[edit]
Bear in mind that the 577 has sophisticated looping compensation circuitry, while the Heathkit and the Vacutrace not.
The Vacutrace has an interesting Z-axis double trace option though.
[/edit]
« Last Edit: September 04, 2009, 02:52:35 PM by 1954U1 »

SUPERMAGOO

Re: curve tracer doubt
« Reply #4 on: September 05, 2009, 08:45:31 AM »
Are you looking for a curve tracer in general or do you need a tube curve tracer?

For a normal curve tracer you can find a Huntron Tracker pretty cheap on eBay...

The Vacutrace seams very nich thou...

sorry! :-[ :-[ :-[ TUBE curve tracer

and this option? is interesting. would not have to use oscilloscope
 http://www.youtube.com/watch?v=LmoEAIUshAE&feature=related

http://cgi.ebay.it/TRACCIATORE-DI-CURVE-INNOVATIVO-TUBE-ANALYZER_W0QQitemZ190322786656QQcmdZViewItemQQptZRadio_d_epoca_Grammofoni_e_Strumenti_musicali?hash=item2c501f4160&_trksid=p4634.c0.m14
« Last Edit: September 05, 2009, 09:28:39 AM by SUPERMAGOO »

SUPERMAGOO

Re: tube curve tracer doubt
« Reply #5 on: December 08, 2009, 04:20:17 PM »
well ...
I got tired of trying to buy a curve tracer.
I'm trying to make one I show in the next video.
any input or help is welcome ...

http://www.youtube.com/watch?v=MbKl8I1JPEw

strangeandbouncy

Re: tube curve tracer doubt
« Reply #6 on: December 08, 2009, 07:01:05 PM »
Hi Supermagoo,


    That looks nuts! I honestly don't have a clue what I am looking at, but I love it! Good luck, Dude!


    Go SuperMagoo!


      ANdyP
. . . . RUH ROH . . . . .

SUPERMAGOO

Re: tube curve tracer doubt
« Reply #7 on: December 20, 2009, 01:10:09 AM »

mad.ax

Re: tube curve tracer doubt
« Reply #8 on: December 20, 2009, 05:10:22 AM »
Hi Supermagoo,

the curve tracer described in your "instructables" link is designed to be used with an oscilloscope...
And the one you show in your video seems to use a PIC and plot the curves on a computer...

I'm wondering about the computerized one... Is it  based on Jack Walton's MCUTracer?
http://www.tech-diy.com/MCTracer_no_pix_files/MCTracer_opto_ver_feb6_04.htm

If not, would mind sharing more details?

Another very simple but PC based (with a nice JAVA GUI) tube curve tracer that looks very promising:
http://www.dmitrynizh.com/plate-curve-tracer-acpc.htm

Axel

SUPERMAGOO

Re: tube curve tracer doubt
« Reply #9 on: December 21, 2009, 03:26:07 PM »
hi.
excuse the messy links.
is that each link to see what I add to the thread.

in the video is the tracer I am doing.
is a voltage ramp with relays (256 steps), controlled by USB interface.
the bias is assigned manually, but sensed by usb.
and consumption THROUGH milliamp is sensing the cathode.
this last if it is not entirely correct.
use a resistive bridge and go to an operational, then is sensed by the usb.

any suggestion is welcome.


mad.ax

Re: tube curve tracer doubt
« Reply #10 on: December 22, 2009, 05:16:23 AM »
Wow! That means 8 relays if I'm right... Something like 0>512 Volts in 2V steps?
Don't you get any spikes when the relays switch on and off?

Also, I am curious about what software you are using? You wrote the code yourself?

Axel

SUPERMAGOO

Re: tube curve tracer doubt
« Reply #11 on: December 22, 2009, 07:42:31 AM »
note that is a first test.
true. the relays generate spikes but the PIC is programmed to move the step, wait, sensing. move 2 volt, wait, sensing. and so the entire ramp.

they seem right?
this well that you do milliamperes sensing cathode THROUGH?

mad.ax

Re: tube curve tracer doubt
« Reply #12 on: December 22, 2009, 09:06:44 AM »
The spikes seems to show up on the curves that I see in your video, that's why I asked...

Not sure I understand your question well, but most of the PC based curve tracers I know of (MCUTracer, Klausmobile, AC/PC) all sense the current trough a cathode resistor.
The main reason being that the low voltage on the cathode is compatible with the 0>5V input range of the converters.
As long as you test triodes this is not a problem because Ik = Ia + Ig and grid current is negligible.
Could become a problem if you plan to add screen current in the equation...

Axel

SUPERMAGOO

Re: tube curve tracer doubt
« Reply #13 on: December 22, 2009, 09:36:37 AM »
excuse my terrible English. :-[
your answer is correct.
at the cathode have the consumption of the plate + screen.
Therefore I think that the measurement is not correct for cathode tetrodes.
that's why I added that other link where OpAmps placed on high voltage.
the question a bit better ... for tetrodes "continuous development of the tracer measured by cathode? or modify it to direct sensing in the plate?

or might sensing the current screen and subtract the result of the measurement of cathode?
« Last Edit: December 22, 2009, 12:17:03 PM by SUPERMAGOO »

mad.ax

Re: tube curve tracer doubt
« Reply #14 on: December 22, 2009, 12:06:48 PM »
cathode measurement shows all the current flowing trough the tube from B+ to ground, VIA the tube.
So unless your tetrode or pentode is triode straped, cathode will read the anode current + the screen (s) current.

I cannot read the schematic in your other link (because instructables.com is not a free site, they just give you previews)
but the text description looks OK. Need a good precision divider though...

In order to sense the screen current, you would have the same high voltage problem than with the anode current.

SUPERMAGOO

Re: tube curve tracer doubt
« Reply #15 on: December 22, 2009, 12:16:43 PM »
thinking better ... what you say is correct. :)
I think it is best to reconfigure everything as miliamp over high voltage sensing. ::)
I have to break my head thinking how! ??? ??? ???
« Last Edit: December 22, 2009, 12:18:49 PM by SUPERMAGOO »


 

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