Curve tracer use in testing componenets

[Gaber Mohamed Boraey]

Hello everyone

I've read that it possible to use the curve tracer in testing components, I can understand how use it for testing doide, zener, resistor, capacitor, etc
But don't know how use for test power mosfet, igbt and transistor

For ex: if testing power mosfet and the mosfet have built in doide " Body Doide", the tracer give the doide shape, for me means that the tracer only see the doide,

I've read little and watched videos about tracer and how help in circuit fault locate and comparison between two boards, one good and one with fault for discovering the fault place and bad component

But I hope someone familiar with this device, help me understand how use in testing transistors so I can see graph and be sure that the part function good?

Thanks in advance.

 

[KlausST]

Hi,

I expect such a tester comes for a MANUFACTURER and an ARTICLE NAME.
It should come with a datasheet and an operating manual which describes the fucntion and how to use it.

Klaus

 

[betwixt]

If you have an oscilloscope you can very easily make your own curve tracer to experiment yourself. If you have a timebase (X) output, use it to provide the voltage and use the normal Y input(s) to monitor currents. It maybe as simple as one resistor and two probes needed for a simple check. Obviously, you need a little more circuitry to take accurate measurements but to prove a point it should suffice. Note that the body diode in a MOSFET is not conducting in normal forward operation, it would be a useless component if it did! The MOSFET curve would be shown in one polarity and the diode in the other.

Brian.

 

[danadakk]

Curve tracing/testing typically force current or V and make DC measurements. More advanced
also do AC work.

MOSFET testing :

https://www.vishay.com/docs/90715/an957.pdf

https://www.keysight.com/us/en/assets/7018-03081/application-notes/5990-8733.pdf

Simple but effective Transistor Curve Tracer circuit.

Transistor curve tracer simple circuit schematics DIY print layout NPN PNP Germanium diode curves

www.eddybergman.com

Regards, Dana.

 

[Gaber Mohamed Boraey]

Hi

If you have an oscilloscope you can very easily make your own curve tracer to experiment yourself. If you have a timebase (X) output, use it to provide the voltage and use the normal Y input(s) to monitor currents. It maybe as simple as one resistor and two probes needed for a simple check. Obviously, you need a little more circuitry to take accurate measurements but to prove a point it should suffice. Note that the body diode in a MOSFET is not conducting in normal forward operation, it would be a useless component if it did! The MOSFET curve would be shown in one polarity and the diode in the other.

Brian.

Hi brian
I do see on market devices used with oscillis cope for curve tracer work
I do have oscilloscope and maybe buy this device from market in the future
The main purpose for me would buy to use for testing electronic components and pcb repair
Doews it worth buying?, can it detect fake components for me?, such as fake mosfet or fake IGBT?

 

[andre_luis]

can it detect fake components for me?, such as fake mosfet or fake IGBT?

There are a lot of fakeness behaviours, so there is no binay yes/no way to do that. One way to achieve that could be by comparing the expected against actual curve patterns, you would need to have the ploted curve range over a transparency of one of the first curve and place in the scope screen....indeed not worthy to do. Another way to know if the part is fake would be sacrificing samples, by reaching the maximum rated values for a time to see the Joule effect taking place ( burning it ! ).

 

[Gaber Mohamed Boraey]

Curve tracing/testing typically force current or V and make DC measurements. More advanced
also do AC work.

MOSFET testing :

https://www.vishay.com/docs/90715/an957.pdf

https://www.keysight.com/us/en/assets/7018-03081/application-notes/5990-8733.pdf

Simple but effective Transistor Curve Tracer circuit.

Transistor curve tracer simple circuit schematics DIY print layout NPN PNP Germanium diode curves

www.eddybergman.com

Regards, Dana.

Using this device with oscilloscope capable of testing electronic components?

Just found this amazing item on AliExpress. Check it out!
EGP3,842.44 | TZT VI Curve Tester Two-Channel Input (With Plastic Shell Alternate Display) Shows Four Test Frequencies

https://a.aliexpress.com/_EHT8TLr

 

[dick_freebird]

Curve tracers are kind of "old school" and may lack documentation
about using with modern devices. But I have used old blue boat
anchor Tektronix curve tracers on MOSFETs (in my ICs) and no
real problems (aside from figuring out how not to blow up Try #N).

It's more about knowing what you want to impose and what you
want to see. The instrument is fairly general purpose (but if you
want a 4th terminal, old school may not be for you - try "medium-
old", like a HP414x / 415x semiconductor parameter analyzer
(presuming high voltage >40V / 80V not needed).

 

[Gaber Mohamed Boraey]

like a HP414x / 415x semiconductor parameter analyzer
(presuming high voltage >40V / 80V not needed).

So expensive for me, curve tracer with oscilloscope not do that job with some study from my side?

 

[crutschow]

For ex: if testing power mosfet and the mosfet have built in doide " Body Doide", the tracer give the doide shape, for me means that the tracer only see the doide,

That only occurs if you power the drain-source terminals with the wrong polarity, which then forward-biases the body diode.
Normal operation is plus-drain and minus-source of an N-MOSFET and vice-versa for a P-MOSFET.

Below is the LTspice sim of an N-MOSFET curve-tracer type characteristic-curve display:
You would reverse both source polarities for a P-MOSFET.

 

[BradtheRad]

So expensive for me, curve tracer with oscilloscope not do that job with some study from my side?

These days someone in the market for an inexpensive oscilloscope might find it in a few places. There's:

a) hook-up to a computer soundcard. Often this is via 1/8 inch mic input, sometimes USB. Program has easy time putting display on screen, particularly waveforms in audio range.

b) Standalone programmable device (Arduino, etc) with attached screen. Projects built from these are described in many places.

c) Home-brew led matrix oscilloscope. Many projects have 9x9 length & width. Timescale via 4017 IC. Voltage scale via 3914 IC. Improve the resolution (size) by adding more units to right and upward.

When building your own, expect half of the work to be calibrating switches and knobs.

 

[Gaber Mohamed Boraey]

When building your own, expect half of the work to be calibrating switches and knobs.

I am talking about curve tracer not oscilloscope, the oscilloscope I do have my own

--- Updated Yesterday at 1:22 AM ---

Below is the LTspice sim of an N-MOSFET curve-tracer type characteristic-curve display:
You would reverse both source polarities for a P-MOSFET.

This can be plot on curve tracer screen?, so I know that my mosfet is good?

 

[BradtheRad]

I am talking about curve tracer not oscilloscope, the oscilloscope I do have my own

I forgot we're focussing on curve tracers. For those, projects also turn up on the internet. Or for building simple circuits which apply various ranges of voltage to a component. Or various ranges of two different voltages to more than one terminal of a component.

Example, to change a voltage automatically in steps can be done by means of a shift register or counter.

And sometimes a sine wave generator at low frequency so your eyes can follow a curve. I assembled one of these to test numerous incandescent light bulbs. I had to generate several watts and a 10-second period. I don't have a curve tracer and I wonder if it could do the job if I did.

To insert various resistances in any circuit there are resistor substitution boxes. It can be homemade for cheap.

 

[dick_freebird]

There is of course the paleolithic method of voltage and current sources and meters and the manual writing down of values.

Curve tracers, parameter analyzers and even fancier model extraction racks all just automate to varying degree. Turn knob, poke keypad, run data crunch routine. Take your various results.

But you can get "good enough" for very few measurements' worth of effort using low tech gear. If you pick the right ones.

So what exactly is the need - to actually test devices ongoing? Or to demonstrate use of an instrument (of specific type or not)?

Two readings-sets and two DMMs and one dual power supply will get you VT by pocket calculator or trivial spreadsheet. Two more for k'. Resistor limit the supply and semi-safely get BVdss. There's old timey books on this stuff, like I have one published by Tektronix that goes deep on both tracers and devices. Test your search engine skills at archive.org

 

[Gaber Mohamed Boraey]

For use in testing components and circuit repair

So what exactly is the need - to actually test devices ongoing? Or to demonstrate use of an instrument (of specific type or not)?

 

[crutschow]

This can be plot on curve tracer screen?, so I know that my mosfet is good?

Yes, that would be similar to the screen plot on the curve tracer for a good MOSFET.