DIY Curve Tracer - Page 7 - diyAudio
Go Back   Home > Forums > Amplifiers > Tubes / Valves

Tubes / Valves All about our sweet vacuum tubes :) Threads about Musical Instrument Amps of all kinds should be in the Instruments & Amps forum

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 13th February 2012, 09:34 AM   #61
mogliaa is offline mogliaa  United Kingdom
diyAudio Member
 
mogliaa's Avatar
 
Join Date: Dec 2009
Location: London
Sync pot should help adjusting the triggering of the comparator, not sure if can help adjusting the phase?
__________________
"A mistake is always forgivable, rarely excusable and always unacceptable. " (Robert Fripp)
http://www.bartola.co.uk/valves/
  Reply With Quote
Old 13th February 2012, 01:44 PM   #62
diyAudio Member
 
Join Date: Jan 2008
Location: Southern California
Hi Ale,

Yes, i think you will need 200hz. The phase adjustment cleans up the traces, so each step is syncronized from 0v to you maximum anode drive voltage. Otherwise you will get a trace that is drawn from two partial and adjacent anode drive cycles.

Alfredo
  Reply With Quote
Old 13th February 2012, 03:35 PM   #63
mogliaa is offline mogliaa  United Kingdom
diyAudio Member
 
mogliaa's Avatar
 
Join Date: Dec 2009
Location: London
So does it mean that I need to hack the PCB to get the output O2 from the 4017 counter instead of O4?
How can I adjust phase in this circuit then?
Thanks
Ale
__________________
"A mistake is always forgivable, rarely excusable and always unacceptable. " (Robert Fripp)
http://www.bartola.co.uk/valves/
  Reply With Quote
Old 13th February 2012, 04:55 PM   #64
diyAudio Member
 
Join Date: Jan 2008
Location: Southern California
I do the same thing Tek does on the 570. A pot and a capacitor, it works well.


Click the image to open in full size.
  Reply With Quote
Old 13th February 2012, 05:04 PM   #65
mogliaa is offline mogliaa  United Kingdom
diyAudio Member
 
mogliaa's Avatar
 
Join Date: Dec 2009
Location: London
Hi Alfredo,
The resolution of that image is very low, so can't see. Where do you suggest placing the pot and capacitor? Is it before the rectifier bridge which provides the 100Hz signal? What are the values of the RC network?
Thanks for the help!!
__________________
"A mistake is always forgivable, rarely excusable and always unacceptable. " (Robert Fripp)
http://www.bartola.co.uk/valves/
  Reply With Quote
Old 14th February 2012, 05:15 PM   #66
diyAudio Member
 
Join Date: Jan 2008
Location: Southern California
I use two transformers, one for HV where i use a bridge rectifier to make the Plate drive signal. I also use a small 6.3 volt transformer that i use for the grid step generator, I pass the output thru the phase adjust and then to the schmitt trigger. I dont use a rectifier for the step generator. If you use your transformer just for the step generator then you can bypass the bridge rectifier and you should then get the 200hz without modifying the divider on the PLL.


Click the image to open in full size.
  Reply With Quote
Old 14th February 2012, 08:08 PM   #67
mogliaa is offline mogliaa  United Kingdom
diyAudio Member
 
mogliaa's Avatar
 
Join Date: Dec 2009
Location: London
Feeding the AC directly to the LM311 will require more hacking on the PCB than changing the PLL frequency division from 4 to 2 only one connection to change from O4 to O2 I guess.
Regarding the RC network will add it to play around with the phase adjusting.

Oh man, this is a project that is coming slowly and demanded a lot of effort so far :-)
Can't see the end of this....

Cheers,
Ale
__________________
"A mistake is always forgivable, rarely excusable and always unacceptable. " (Robert Fripp)
http://www.bartola.co.uk/valves/
  Reply With Quote
Old 14th February 2012, 10:37 PM   #68
ChrisA is offline ChrisA  United States
diyAudio Member
 
Join Date: Jan 2008
Quote:
Originally Posted by mogliaa View Post
...
Oh man, this is a project that is coming slowly and demanded a lot of effort so far :-)
Can't see the end of this....
You are doing it the hard way. My curve tracer is using (or will use) software to drive a set of DACs to make the wave forms. The I use ADC to measure. The best part is that today's $5 microprocessors have several ADC and DACs built-in. They typically have only 10-bit resolution but that is more than enough. With the uP the parts count is way down. So with a uP the wave forms are nearly trivial to produce, I still need high voltage supplies and that is where the work goes.

But the down side is that I will not get to see the result on my scope, it will get pushed unto a computer and plotted there.

But there is room for innovation now. How best to display the curves on a computer screen. One now can use 3d color graphics and even animation whereas the old tube data books only had black ink. I'm sure this is where most of the work will need to go.
  Reply With Quote
Old 15th February 2012, 12:26 AM   #69
diyAudio Member
 
SpreadSpectrum's Avatar
 
Join Date: Nov 2007
Chris,

Which microprocessor do you plan on using? I wanted to take a similar approach but need to find a processor that can do a bunch of measurements synchronously(or asynchronously really fast). Otherwise there will be an ADC board with a CPLD or something to make measurements synchronous. I wanted to measure currents from all electrodes and produce some really nice curve data and just plot in Excel.
  Reply With Quote
Old 15th February 2012, 12:52 AM   #70
ChrisA is offline ChrisA  United States
diyAudio Member
 
Join Date: Jan 2008
Quote:
Originally Posted by SpreadSpectrum View Post
Chris,

Which microprocessor do you plan on using? I wanted to take a similar approach but need to find a processor that can do a bunch of measurements synchronously(or asynchronously really fast). Otherwise there will be an ADC board with a CPLD or something to make measurements synchronous. I wanted to measure currents from all electrodes and produce some really nice curve data and just plot in Excel.
The key is that because you are NOT driving a real time display like the analog scope, you can go as slow as you like. With the uP you do not need to retrace a curve at 60Hz, 1Hz is fine. You don't need the "really fast" part. Put yes you do need "synchronous". technically there is no reason you can't set a voltage on say the grid, then wait 10 minutes to measure the current, as long as the voltage you set does not change. I will not wait 10 minutes but I do consider all the voltages to be "DC"

You can set the voltages, wait for them to "settle" and measure each current one at a time, store to a file, then step to the next voltage. If the whole process takes 10 seconds no big deal.. I can see doing 6,000 data points per tube and doing about 100 per second, could take one minute. I don't know the real rates yet.

A scope needs to be re-freshed before the phosphor fades but computer memory does not need the re-fresh.

There are cheaper uPs but I like the Arduino. Mostly because it is easy and because it will be easy for others to also use and program it. If it is easy then maybe people will do it. Main criteria is if people new to uP can use it. Arduino sees to be dead-easy. Even if it does add $30 to the project.

Current state is just the very beginning with breadboard experiments to prove some techniques. one for example is how to pass analog data through an opto-coupler and how linear is the result. First try failed. Next try showed it could be done. Next will use paorts I have on order. Lots of things like this to check out..

Last edited by ChrisA; 15th February 2012 at 01:00 AM.
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
DIY Curve Tracer for PC locky_z Solid State 455 2nd August 2014 07:13 AM
B-H Curve Tracer gpapag Equipment & Tools 9 16th January 2011 08:22 PM
curve tracer barclaycon Equipment & Tools 6 11th February 2010 08:10 PM
Wanted Diy curve tracer! amc32 Car Audio 1 19th October 2009 05:52 AM
DIY tube testing Curve Tracer whitelabrat Tubes / Valves 5 24th October 2007 09:11 PM


New To Site? Need Help?

All times are GMT. The time now is 09:43 AM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2