Curve Tracers

Curve tracers provide the experimental observations that let people write the spice models which we use in out simulation programs.

They put changing currents or voltages into a device, and record the currents or voltages that come out.

For slow stuff, D/A converters can provide the input and A/D converters can now record the outputs. That won't need boat anchors.

The main challenge would be working out what devices you'd want to look at. Once you'd done that you'd just have to read the literature - and in your case, learn to understand it.

Your expedition into climate science fell down on that point.

I've considered it. It would be much more valuable if it traced capacitances too.

The display should be on a computer and the data archived.

I often just set up a breadboard and test parts. Last week I blew out some power mosfet gates. Some have internal zeners; this one doesn't.

Most mosfets drain avalanche, but the voltage is never specified, in fact deliberately hidden. I have to measure that. A good curve tracer should measure that too.

Currents should go down to picoamps.

The fact that there aren't many curve tracers for sale suggests a small market.

A bit more modern way to do this is get one of those HP data acquisition units like a 34970A with a multiplexer card, and a multi-output PSU that can both be controlled over GP-IB

Meanwhile, in China:

Someone seems to still banging out 1970s-style CTs

Barbaric.

Last chance buy before tariffs kick in and HP re-instates its whole 1987 catalog to meet the demand for domestically-produced test gear.

You buy one. Give us a review.

I think that the function is now done by a Fluke Data Bucket (or equivalent) in an ATE (Automatic Test Equipment) that controls collection of data, which is later plotted in a computer.

Joe Gwinn

A VNA is best for that. I've been using my big HP one this afternoon to label some random bunches of caps and inductors whose values I couldn't read. Trouble is, there doesn't seem to be much agreement on what frequency to test these devices at. I've heard 100khz, 1Mhz, 10Mhz and

For people such as yourself, certainly. For me as a hobbyist, a CRT is fine.

I can kill a MOSFET at 50' just by looking at it (certainly in winter). In fact I shock myself from all the static I build up and it ain't funny. Having dry skin is great for when I touch HV by accident (happens quite a lot) but the flip side is I accumulate and hold static charge like no one else I know.

But a market, though small perhaps, there must be.

Yes, Trump may well be throwing them a lifeline. HP products might once again be craned and fork-lifted into RF developers' labs across the nation!

I can't see any price listed for the Chinese CT for some reason. Any idea how much it is?

I must admit I hadn't really thought about anything display-wise beyond hijacking a scope's CRT for the purpose. But I can see where you're coming from here. It would be *way* too much for *my* needs, but I can see the merit of it for pro designers.

Perhaps you should consider developing one for production purposes?

Nah, real men use an HP 4145B. Exceptionally Good Medicine.

Cheers

Phil Hobbs

God only knows what will actually be affected. Seems unlikely they'll hammer consumer goods like iPhones etc. too hard or the hoi polloi will scream murder. More likely intermediate and semi-finished goods..

$3500 for the basic version with a CRT and $4800 for the one with an LCD display and looks to have some more more advanced features.

And whatever it costs for the Mandarin lessons to read the manual/front panel.

Heh. Boat anchor for sure. But it had real knobs, and no Windows.

And isn't it a bit limited - only tests old semiconductors ...

Joe

Production semiconductor test is a big business. Automated, not benchtop instruments with CRT analog displays.

A curve tracer could be a small USB box.

I now that there are some cool "pin driver" ICs that are used in semi testers and are not available to us civilians.

Something like $3500.

Carly didn't like electronics so dumped the test equipment and made HP a computer company. That was sure dumb.

Agilent acquired the HP stuff and spun out Avago and Keysight.

What I want is C-V curves. I guess a VNA can do that with a some bias tees and various power supplies.

You have to read the analog screen and write down numbers. Or take a picture.

Some fets have protective gate zeners. They typically clamp at +-40 volts.

Here in San Francisco, we never get static zapped. High humidity.

Sure. It would be a fun project.

GPIB ain't modern! It's 50 years old.

Ever read the actual spec? The state diagrams will give you nightmares for weeks.