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Curve tracers

The basic 576 *incorporates* pulsed measurements, as well as swept.

300 microseconds and 80 microseconds. Bottom row of buttons on the right hand side. It does that at a single operating point at a time, if you want a plot, you have to draw it by hand.

Methinks you are not that familiar with the 576. I use one or other of the two in my lab on an almost daily basis.

The 176 is an addon unit that fits in place of the standard test fixture, that goes to 200 amps. It is pulsed mode only, using delay line charge storage, to avoid enormous, heavy power supplies, unlike the 175, that needed two people or a fork truck to carry it.

--
"For a successful technology, reality must take precedence  
over public relations, for nature cannot be fooled." 
                                       (Richard Feynman)
Reply to
Fred Abse
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Agilent has a USB curve tracer offering, but needless to say it costs a lot more than the Anatek gizmo, and does not offer pA resolution. Search on U2722A.

James

Reply to
arlo613

beta,

you

idea

specified

without

voltage,

  1. A

because

Sure, I'm in. Do you think it might actually sell?

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs 
Principal Consultant 
ElectroOptical Innovations LLC 
Optics, Electro-optics, Photonics, Analog Electronics 

160 North State Road #203 
Briarcliff Manor NY 10510 USA 
+1 845 480 2058 

hobbs at electrooptical dot net 
http://electrooptical.net
Reply to
Phil Hobbs

generate

beta,

tracer

analyzer

mind

day.

you

of

rough idea

specified

without

voltage,

  1. A

because

Well, some for sure. Ten a year? 200?

Time to start scribbling.

--

John Larkin         Highland Technology, Inc 

jlarkin at highlandtechnology dot com 
http://www.highlandtechnology.com 

Precision electronic instrumentation 
Picosecond-resolution Digital Delay and Pulse generators 
Custom laser drivers and controllers 
Photonics and fiberoptic TTL data links 
VME thermocouple, LVDT, synchro   acquisition and simulation
Reply to
John Larkin

I'd be happy to volunteer embedded software work. Pretty much what I do is measurement instrumentation software and associated Windows software, where needed.

For EM1 level: BF, BR, IS Measure ambient temperature near the BJT [and hold Vbc near 0 to avoid power dissipation as is assumed in EM1] and also require doing this at several ambient temperatures to get Eg and perhaps the power of T [nominally 3 in the IS(T) equation, but if allowed to change freely then becomes part of the curve fitting algorithm, which I can also write.] By the way, the Tek 577 achieves base currents of 5nA with the

177 porch. Not sure how low you'd like to achieve.

For EM2 level: Ohmic re', rc', and rb'; Cjeo, Cjco, C-substrate; forward and reverse transit times; gradients for the EB and CB capacitances and their barrier potentials. Things aren't always straightword. If you attempt to measure re', for example, by driving known base currents and observing Vce (with open collector), there is a flyback effect caused by a decrease of BR at low currents which should be taken into account. The re' value is best gained as

1/slope near that flyback point than somewhere else on the curve. But not confused by the actual flyback itself.

Jon

Reply to
Jon Kirwan

You insist on talking about how a 576 works. I'm talking about the measurement you're making. If what you're measuring is what you want, you're good to go.

If you want to DESIGN a curve tracer, you might want to be concerned with the relationship between what you measure and the picture on the display. For a qualitative display, it doesn't matter a lot.

If you're reading out three digits of precision, you need to think about dynamic temperature effects.

You can do it either way...just understand the difference.

You have me beat. I have only one. I bow to your quantitative superiority. All I can tell you is that, back in the day, I tried to build a curve tracer that graphed static measurements. I didn't like the result and aborted the project. It was not as trivial as I thought.

Reply to
mike

Hi Phil,

Do you have the manual for the 72BD?

regards

Reply to
tm

The Boonton also outputs BCD on the rear connector.

Reply to
tm

I have a softcopy of the user's manual, but no service manual or schematics.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs 
Principal Consultant 
ElectroOptical Innovations LLC 
Optics, Electro-optics, Photonics, Analog Electronics 

160 North State Road #203 
Briarcliff Manor NY 10510 

hobbs at electrooptical dot net 
http://electrooptical.net
Reply to
Phil Hobbs

If I find an electronic copy I'll let you know.

tm

Reply to
tm

If you're reading three digits of precision, I would recommend reading the sheaf of application notes put out by Keithley on the subject of semiconductor characterization. It's decidedly nontrivial.

--
"For a successful technology, reality must take precedence  
over public relations, for nature cannot be fooled." 
                                       (Richard Feynman)
Reply to
Fred Abse

Thanks!

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs 
Principal Consultant 
ElectroOptical Innovations LLC 
Optics, Electro-optics, Photonics, Analog Electronics 

160 North State Road #203 
Briarcliff Manor NY 10510 

hobbs at electrooptical dot net 
http://electrooptical.net
Reply to
Phil Hobbs

he

TransAm

it,

M3

he

for

start

to

the

If he really goes into software he will eventually take an os course. If he does this now he will be miles ahead by then. I know, this was part of my first os course. He could also delve into searching and sorting, b-trees, and timer queues. All relevant at the os level. Serching, sorting and b-trees (and the variants) are all generally applicable.

?-)

Reply to
josephkk

generate

V_BE, and

computation of beta,

parameters like

with a

curve tracer

analyzer

wouldn't mind

of rack

the day.

measurement

the

constant.

parasitics, unless you

femtofarads.

device.

serious

simple as it

Most of

with lousy

expensive.

tracer.

you a rough idea

The specified

assume, without

supply voltage,

avalanche at 25. A

at all, because

100

simple

USB

a

Maybe

that way.

We might make two or more models. Some dependency on price, features, and performance for sales outside this ng. Within the ng we could probably make and deploy one to two dozen. Then with real world experience i think we could do a better job of selling it outside.

?-)

Reply to
josephkk

Ebbers-Moll is ok for bipolar but i would like to get Gummel-Poon models. MOS models are a different subject that i didn't get to study.

?-)

Reply to
josephkk

your

would

points

particular

not

right

want

BTDT. I have some grasp and this project looks like a ton of fun but likely beyond the best i can do alone, even if i had the time. To avoid the half ton power supplies we use pulsed mode measurements. With so much of everything now being focused on low power for battery use, USB powered could do much of what we want, and add a brick for moderate power pulsed measurements. Good clean ramps and steps (in both voltage and current are not simple) and adding pulse measurements to that gets seriously hard core. Some here could do it all by themselves, but i suspect no one would volunteer to do it all without a contract.

fixture,

Reply to
josephkk

about

the

Thanks for the heads-up. I am not sure we are going to do anything that need these, but it will be nice to have them.

?-)

Reply to
josephkk

I agree. I was just pointing out that it starts out interesting at the DC level and gets even more interesting later. This is an area I really enjoy.

Take VA. The easiest way is to extrapolate Ic vs Vce in the CE configuration. But the error can be very high. Another way is to measure the slope very near Vbc=0. Another way, though, is using ln(Ic) vs Vbe at two different Vbc values, computing it as a ratio. And it's better done that way. But that assumes basewidth modulation is negligible. So additional tests using different Vbe to see how well the assumption holds may be useful.

I'll be picking up a few BJT testers; 575, 577, and fairchild

6200, in a couple of months.

I'm in a similar boat. I've only basic knowledge here. They don't seem as intriguing, though.

Jon

Reply to
Jon Kirwan

generate

and

beta,

like

tracer

analyzer

mind

rack

day.

measurement

unless you

serious

it

of

lousy

expensive.

rough idea

specified

without

voltage,

  1. A

all, because

How practical do you think it would it be to add temperature characterization? I'd be interested in that.

Best regards, Spehro Pefhany

--
"it's the network..."                          "The Journey is the reward" 
speff@interlog.com             Info for manufacturers: http://www.trexon.com 
Embedded software/hardware/analog  Info for designers:  http://www.speff.com
Reply to
Spehro Pefhany

generate

and

beta,

like

a

tracer

analyzer

mind

rack

day.

measurement

unless you

serious

it

Most of

lousy

expensive.

tracer.

rough idea

specified

without

voltage,

at 25. A

all, because

simple

way.

Just a SMOP. Measure Delta V_BE at three known currents, dancing back and forth as needed to take out the effects of drift and R_E. Should be able to get Theta_JA and maybe the thermal mass of the die + paddle.

I'd like to be able to measure noise as well.

It will be interesting to figure out how to make a test fixture that prevents all transistors from oscillating under all conditions. Maybe the thing to do is to sell the tracer cheap and make money off the disposable test boards. (Shades of early IBM.)

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs 
Principal Consultant 
ElectroOptical Innovations LLC 
Optics, Electro-optics, Photonics, Analog Electronics 

160 North State Road #203 
Briarcliff Manor NY 10510 USA 
+1 845 480 2058 

hobbs at electrooptical dot net 
http://electrooptical.net
Reply to
Phil Hobbs

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