Show Us Your Curve Tracer

[Electro Fan]

I was reading about this guy's (named Paul) project:
http://www.paulvdiyblogs.net/2017/
And his latest version 3 of it:
http://www.paulvdiyblogs.net/2021/03/building-curve-tracer-version-3.html

Looks interesting to me, but I don't have a curve tracer yet. I'm quite interested in acquiring a curve tracer, but not in a big hurry, so maybe I'll wait until he's finished version 3. Anyone have any opinions on his approach?

Prior to this thread while looking at curve tracers from the high end to the entry level, and especially at the ELV and successor designs, I came across Paul's work which has evolved into the VBA curve tracer.  Fwiw, the work done by Paul and his colleagues was something that helped stimulate this thread.  It struck me at the time that Paul's project was a potentially very good or maybe excellent approach to designing a curve tracer that could address a lot of needs and interests, possibly at the professional/commercial level and definitely at the academic/teaching level and at the enthusiast level.  IMO, Paul (V) and his colleagues (B and A) have been on a very thoughtful, open, tenacious, and admirable path and I'd bet that they will continue until they are confident they are "there."  And my guess is they might keeping going with further enhancements and ideas beyond "there."  I'd love to see V, B, and A participate here and have the opportunity for forum members to become a sounding board, adopters, and potentially contributors to the advancement of the VBA curve tracer.

[Shock]

Get them to post about it in the projects forum, it's there to discuss projects.

I'll also add it's not so much a resurgence in curve tracers but electronics more accessible and collaborative, especially with video streaming. Dave himself mentioned about lurking in the electronics newsgroup back in the day, it was fairly primitive.

Online auction/classified sites also give us access to cheaper gear and at some point past the multimeter, scope, psu stage people may want to characterize components. So it's not like curve tracers are the next biggest thing, they have always been around, we just don't have wait months to discover a cheap design in a magazine anymore. Now it's go on youtube or ebay and a few bucks later you can get a basic IV curve. Or many curves if you throw more money at it.

[Dwaine]

Here is my setup....

[antenna]

I went as cheap as I could. An old DC adapter cut open to convert to AC (5.82vRMS), a 400ohm resistor, a BNC jumper cut in half and the probe from my LCR meter. Picoscope 3206D XY mode with custom probes programmed to get the scales correct.

[Messtechniker]

Poor man's curve tracer on the Hameg HMO 1022 scope:



Same green LED connected to DL4JAL curve tracer:

[david77]

Here's my copy of the ELV KS7000. It works quite well and has turned out to be a useful tool for the workshop when fixing stuff.

Hooking up devices with clip leads was not only very messy and annoying, it also resulted in nasty oscillations. So I decided to go the
Tektronix route and made up a testfixture. So far I've got this one that works for small & medium power transistors. I've got parts on order to make another one for TO3 packages. This works very well so far.

Certainly no Tek but ok for me.

[Neomys Sapiens]

I posted some of my initial experiences with the Peak Electronics DCA75
here:
https://www.eevblog.com/forum/testgear/test-equipment-anonymous-(tea)-group-therapy-thread/msg3530794/#msg3530794
,here:
https://www.eevblog.com/forum/testgear/test-equipment-anonymous-(tea)-group-therapy-thread/msg3671740/?topicseen#msg3671740
and here:
https://www.eevblog.com/forum/testgear/test-equipment-anonymous-(tea)-group-therapy-thread/msg3503112/?topicseen#msg3503112

Besides this, I have the model 3110 from Vu-Data corp., which seems to be a (licensed?) copy of an earlier Huntron model, maybe tre Tracker 1000.

[AaronLee]

Here's my copy of the ELV KS7000. It works quite well and has turned out to be a useful tool for the workshop when fixing stuff.

Hooking up devices with clip leads was not only very messy and annoying, it also resulted in nasty oscillations. So I decided to go the
Tektronix route and made up a testfixture. So far I've got this one that works for small & medium power transistors. I've got parts on order to make another one for TO3 packages. This works very well so far.

Certainly no Tek but ok for me.

Wow, impressive!

[Messtechniker]

Hooking up devices with clip leads was not only very messy and annoying, it also resulted in nasty oscillations.

Had the same problem with my DL4JAL curve tracer.
Fitting a small ferrite bead in the collector line fixed that.

[david77]

Had the same problem with my DL4JAL curve tracer.
Fitting a small ferrite bead in the collector line fixed that.

Yes, I did the same inside my fixture. Killed all the nasties instantly.

[Electro Fan]

As discussed earlier in this thread, this project is showing a lot of excellent potential:

https://www.eevblog.com/forum/testgear/diy-curve-tracer-(analog)/

[KungFuJosh]

I had a terrible experience with a popular tube curve tracer. As a result of that experience, I designed better hardware, and hired somebody to create new firmware. The result is what I'm calling the FUtracer (for obvious reasons if you're familiar with the one that pissed me off).



It's setup to test (from left to right):
12AX7 etc...
EF800 etc...
EF86
EL84
EL34/6L6/6V6 etc...

It can be setup for whatever tube types/sockets you want, but those are the ones I cared about, so that's what's on the tube pcb part.

Here's the Windows GUI:


Here's my ridiculous / overkill test I did. 301 points from Va 2 to 400, with 31 sweeps of Vg from 0 to -30:

[Johnny10]

All the popular guitar amp tubes.
Cool! 

Can you switch between triodes?

[Cubdriver]

That thing looks sweet!!  Very nicely done!

-Pat

[KungFuJosh]

All the popular guitar amp tubes.
Cool! 

Can you switch between triodes?

There's no need to switch, it tests both triodes in dual triodes at the same time. Though technically you can switch between them on the plot tab in the GUI. You can show both Ia1 and Ia2, or show either. I'll take a new test and post it later, but this is what the plot screen looks like:

That thing looks sweet!!  Very nicely done!

-Pat

Thanks! I'm probably going to sell the PCBs along with the programmed PIC chip if anybody is interested. Though there are a few SMD items on there, so it's not a project for everybody. If there is enough interest, I might find an SMDA service that carries the parts I use, but I don't want to do it as a service myself. I do it well enough, but not well enough to charge for it. 🤣

Overall, it's not that expensive to build. The BOM on Mouser is about $180 or so with all premium parts, and I was thinking about selling the boards (main PCB, tube socket PCB, and a external PSU connection PCB) and programmed firmware chip for like $150 shipped in the US.

Thanks,
Josh

[Johnny10]

Is this full voltage or like uTracer short pulse. Is the Gm from database or calculated?

[KungFuJosh]

Is this full voltage or like uTracer short pulse. Is the Gm from database or calculated?

It's pulsed, most tube testers are pulsed (there are a couple that aren't that have their own limitations). Gm is calculated. The GUI is a special newer version of utMax (which is open source), and it has modeling (modeling currently needs to be fixed though) for better Gm readings based on operating point.

[Cubdriver]

I would definitely be interested in building one of them!

-Pat

[KungFuJosh]

I would definitely be interested in building one of them!

-Pat

Awesome, I'm glad to know there's more interest out there. My tube amp forum obviously has interest too. I'll need to buy more PIC chips before I can sell more than...2 lol. But also, unless you have a stockpile of convenient parts, a lot of the parts on the BOM are backordered until next year. Yay for covid supply chains. 🙄

I'll eventually build a website with build info and share the link here.

How are you with SMD stuff? There's a few tiny things on there. 😉

Thanks,
Josh

[Cubdriver]

Awesome, I'm glad to know there's more interest out there. My tube amp forum obviously has interest too. I'll need to buy more PIC chips before I can sell more than...2 lol. But also, unless you have a stockpile of convenient parts, a lot of the parts on the BOM are backordered until next year. Yay for covid supply chains. 🙄

I'll eventually build a website with build info and share the link here.

How are you with SMD stuff? There's a few tiny things on there. 😉

Thanks,
Josh

Haven't played too much with SMD stuff thus far, but do have a preheater, a hot air tool, and fine tips for my regular iron.  And yeah, the supply chain is a total clusterfuck.  Been dealing with it trying to get parts for work - it's crazy.  Stock expected six or more months down the road.  On things like Molex Connector housings.  WTF?   

-Pat

[KungFuJosh]

Haven't played too much with SMD stuff thus far, but do have a preheater, a hot air tool, and fine tips for my regular iron.  And yeah, the supply chain is a total clusterfuck.  Been dealing with it trying to get parts for work - it's crazy.  Stock expected six or more months down the road.  On things like Molex Connector housings.  WTF?   

-Pat

I recommend trying out some of the SMD practice kits on Amazon. I built a few before I attempted this build. I have a few more to build for practice/fun.

On my tracer PCB:
Here's one difficult one (only one of them obviously): https://www.mouser.com/ProductDetail/895-FT232RL
And there's two of these: https://www.mouser.com/ProductDetail/595-PGA113AIDGST

I use solder paste for both of those, but for some reason the PGA113s are trickier than the FT232RL for me. The pin pitch seems almost the same. Maybe it's cause there's two. lol There's a few other easier items, only basic SMD skill is really needed for.

I've had some luck going back and forth between Mouser, Arrow, and Digikey or Newark for supply stuff. But it's obviously gotten much worse.

Thanks,
Josh

[Johnny10]

At least your not trying to remove SMD.
I find it very trying. Its a different world now. Parts that can fly!
I keep looking at the JCB NANO kit but big $$$$$$

[KungFuJosh]

At least your not trying to remove SMD.
I find it very trying. Its a different world now. Parts that can fly!
I keep looking at the JCB NANO kit but big $$$$$$

Removing SMD is much easier. I have one of those "fast chip" magic goo kits. SRA sent me this free with some other stuff once upon a time: https://www.amazon.com/Fast-Chip-Removal-Temperature-Alloy/dp/B015RV4NBS

It takes seconds to remove annoying SMD stuff with that. I really think Magic Goo would be a better product name. I suppose it would be harder if the pins aren't visible though.

[rsjsouza]

Haven't played too much with SMD stuff thus far, but do have a preheater, a hot air tool, and fine tips for my regular iron.  And yeah, the supply chain is a total clusterfuck.  Been dealing with it trying to get parts for work - it's crazy.  Stock expected six or more months down the road.  On things like Molex Connector housings.  WTF?   

-Pat

I recommend trying out some of the SMD practice kits on Amazon. I built a few before I attempted this build. I have a few more to build for practice/fun.

On my tracer PCB:
Here's one difficult one (only one of them obviously): https://www.mouser.com/ProductDetail/895-FT232RL
And there's two of these: https://www.mouser.com/ProductDetail/595-PGA113AIDGST

I use solder paste for both of those, but for some reason the PGA113s are trickier than the FT232RL for me. The pin pitch seems almost the same. Maybe it's cause there's two. lol There's a few other easier items, only basic SMD skill is really needed for.

I've had some luck going back and forth between Mouser, Arrow, and Digikey or Newark for supply stuff. But it's obviously gotten much worse.

Thanks,
Josh

Josh, if you are talking about supply troubles, the FT232RL can be sourced in many USB-to-serial converters (you may even use a serial connection and plug an external adapter). The PGA113AIDGST seems to be in stock in TI's page. 

If you are talking about soldering alone, then yeah, it is worth practicing on some older boards or kits. Also, you need to see things - get a powerful loupe with good lighting, a stable soldering iron with a thin and clean tip and good solder paste and solder.

BTW, your curve tracer looks quite interesting; congratulations on making it.

I might not have enough capex to commit at this moment, but I will keep this in mind.

[KungFuJosh]

Josh, if you are talking about supply troubles, the FT232RL can be sourced in many USB-to-serial converters (you may even use a serial connection and plug an external adapter). The PGA113AIDGST seems to be in stock in TI's page. 

If you are talking about soldering alone, then yeah, it is worth practicing on some older boards or kits. Also, you need to see things - get a powerful loupe with good lighting, a stable soldering iron with a thin and clean tip and good solder paste and solder.

BTW, your curve tracer looks quite interesting; congratulations on making it.

I might not have enough capex to commit at this moment, but I will keep this in mind.

Thank you! It was quite the journey getting it to where it is.

I have stock of everything. 😉 But I'm not selling the parts; when I do, it will just be the boards and the programmed chip. SPA07N60C3, LM7805CT/NOPB, DR127-331-R are all hard or impossible to get right now, and there's a bunch of other stuff out of the ~92 items on the BOM for the main PCB that have supply issues.

For SMD work, I use my Andonstar AD208 digital microscope. It does a pretty darn good job. No lag issues if you don't max the resolution.

My soldering station is an Aoyue 2703A+ (I've been abusing this one for over 4 years- the last 3 stations I had from other brands didn't last that long). The hot air works great for the SMD stuff. I use Kester EP256 solder paste- it works well but sometimes is a pain in the ass to stick at first.

Thanks,
Josh