pointers to transistor (semiconductor) curve tracer circuits/projects

Am 29.10.18 um 22:57 schrieb John Larkin:

He asked an on-topic question and got shitty, off-topic answers, all of them but maybe 2 or 3. Your's was none of the 3.

Gerhard

Reply to
Gerhard Hoffmann
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ps and cassette decks that have house numbered semiconductors, mainly trans istors as well as JDEC p/n that are NLA.

ortunately, they are in parts of the amp where the other channel has an ide ntical transistor.

o the original.

s the curves on a scope - cute but not precise enough for my intentions. I am more interested in a lab type instrument.

hed to it that have some A/D's on them that can record the data of interest (e.g. Ib (vb), Vce, etc.

of 5V max on the input for the A/Ds and don't want to scale it.

with a micro but they seem to be very scarce, in addition to having transis tors in them that are NLA.

ng where someone has 'plowed the ground' and at the very most, I'd have to augment it with a micro. Yea, I am a bit lazy - the intent was to fix the amp, not develop a curve tracer....

Right, schematics would help a lot. GH

Reply to
George Herold

=================================================

There was an article in QST magazine (April, 2015) "Mini-CT: A Curve Tracer for the Ham Shack" by Veikko Kanto N7VK describing a curve tracer using a C8051F121 microcontroller. The article is at

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however, the software seems lost to oblivion. I couldn't find it on the QST web site. A thread on EEVBlog gives his location
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You might be able to contact him for a copy of the software and any further development of the project. From a perusal of the article, it appears that he provided a data recording feature in the software. Perhaps, if you could contact the author, some further development could give you a good portrtion of what you're after in a curve tracer.

Good luck with the project. It would make a great follow-up article for QST or another magazine.

Cheers, Dave M

Reply to
Dave M

I answered first, and my response was civil and relevant. He didn't answer my question about schematics.

He apparently resents not getting free consulting, and resents discussion drift. It's an unmoderated public forum; get used to it.

--
John Larkin         Highland Technology, Inc 
picosecond timing   precision measurement  
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Reply to
John Larkin

This is not facebook and and nothing like as controlled, or as PC, thankfully...

Chris

Reply to
Chris

n.I have some high end audio gear from the 80s and I do some repair for fri ends/clients. I also do format conversions for myself and other ppl.

lated or begged the question about usefulness. I always thought that an IQ test should be given to ppl before they got an on-ramp to the net. Most w ould fail the test.

r perspective on audio or electronics, your political view, or what your fa ther did or did not do. Mine was a WWII vet - fighter pilot but has nothin g to do with the question I asked.

have a Nakamichi 1000ZXL. It appears his preamp died. I didn't challenge him as to why he *still* uses it...to each their own.

I did reply to your first post but I forgot and did it in my email and it d idn't get posted. To address your points:

1) I usually try to find schematics, sometimes not very successful. If I do have schematics, I try to model it to see how it performs (if it is someth ing I am not familiar with). I did answer the question of noise. 2) There are lots of reasons why curve tracers are no longer made by Tek, H P, etc. My speculation is that as a business decision, it is not profitabl e because ppl solve the design problem with different technology rather tha n with discrete transistors. That does not imply the use/application is us eless. 3) I know a curve tracer does not provide any insight as to noise character istic, and I know that noise is a concern - especially in old clunky electr omechanical beasts like cassette deck. If you look at some of the designs and implementations, some of the low noise solutions are quite elegant. 4) Discussion drift - that is true, I resent it. I ask a technical questio n on a technical group and expect the answers to be technical. As one read er pointed out, most of it was not. 5) free consulting - is appreciated, and thanked in kind. Just because an a pproach doesn't do something doesn't mean the approach is invalid for other things. Because curve tracers do not provide insight on noise characterist ics doesn't me they aren't useful for their intended purpose. I have a fai rly solid academic background in EE but admittedly rusty in certain areas. I took extra courses in semiconductor physics even though it was not my m ajor and that was many years ago. 6) unmoderated public forum. Right - anybody can say anything on any topic . My expectations for ppl to stay on topic was apparently incorrect. My e xpectation of professionals providing feed back in a professional manner wa s not met by a number of the responses, to which I am unpleasantly surprise d. I am used to a higher standard, even in unmoderated groups. My expecta tions have been 'recalibrated.' I appreciate the helpful feedback from you and other. Peace, J

n.I have some high end audio gear from the 80s and I do some repair for fri ends/clients. I also do format conversions for myself and other ppl.

lated or begged the question about usefulness. I always thought that an IQ test should be given to ppl before they got an on-ramp to the net. Most w ould fail the test.

r perspective on audio or electronics, your political view, or what your fa ther did or did not do. Mine was a WWII vet - fighter pilot but has nothin g to do with the question I asked.

have a Nakamichi 1000ZXL. It appears his preamp died. I didn't challenge him as to why he *still* uses it...to each their own.

Reply to
jjhudak4

Looks very interesting and applicable. I'll check it out. TYVM J

Reply to
jjhudak4

mps and cassette decks that have house numbered semiconductors, mainly tran sistors as well as JDEC p/n that are NLA.

Fortunately, they are in parts of the amp where the other channel has an id entical transistor.

to the original.

ws the curves on a scope - cute but not precise enough for my intentions. I am more interested in a lab type instrument.

ched to it that have some A/D's on them that can record the data of interes t (e.g. Ib (vb), Vce, etc.

of 5V max on the input for the A/Ds and don't want to scale it.

with a micro but they seem to be very scarce, in addition to having transi stors in them that are NLA.

ing where someone has 'plowed the ground' and at the very most, I'd have to augment it with a micro. Yea, I am a bit lazy - the intent was to fix the amp, not develop a curve tracer....

535945536/lightbox/

Looks useful but deciphering its documentation might be an equation with to o many unknowns...I'll contact him for more details, or you if agreeable to it. Thanks J

Reply to
jjhudak4

I have some high end audio gear from the 80s and I do some repair for frien ds/clients. I also do format conversions for myself and other ppl.

ted or begged the question about usefulness. I always thought that an IQ t est should be given to ppl before they got an on-ramp to the net. Most wou ld fail the test.

perspective on audio or electronics, your political view, or what your fath er did or did not do. Mine was a WWII vet - fighter pilot but has nothing to do with the question I asked.

ve a Nakamichi 1000ZXL. It appears his preamp died. I didn't challenge hi m as to why he *still* uses it...to each their own.

Thank you. A bit pricey for my needs but if they come down to

Reply to
jjhudak4

Reply to
tabbypurr

h
t
Reply to
jjhudak4

e

hows

.
,
** Assuming that using a curve tracer is the answer to your prayers is wors e than rusty.
** Better post them right here.

However, without actual units to do tests on and/or clear schematics, the t ask can become near impossible. I can point out what clues to look for but you have to find and make good use of them.

Experience with actual repairs soon revealed to me that manufacturers mostl y chose particular semis ( BJTs, JFETs etc) because they were cheap and rea dily available - or at least were to them at the time. Not because their e lectrical characteristics were so special nothing else would do as well or better.

Having said that, one does need to get the basics right - ie substitutes sh ould be in the same package, have sufficient breakdown voltage, power handl ing, Hfe, correct polarity etc. If devices need matching ( ie input diff pa irs or output BJTs in parallel ) - then knowing how to do that job reliably is important too.

.... Phil

Reply to
Phil Allison

nd

oth

n't

ght learn something useful that I didn't know, since this isn't my daily e ngineering work.

You could always add little glitches on the display every 10 units or so. But as Phil more or less said, modern commercial circuits are designed to n ot care about a fair spread of transistor values.

NT

Reply to
tabbypurr

Small-signal bipolar transistors just aren't very interesting; all the curves look about the same. Beta is all over the place anyhow. For audio, just get a decent part with good beta and enough Vcbx or something. A curve tracer won't tell you Ft or capacitances or noise.

A curve traces is more useful for fets, especially RF parts where the data sheet often has no DC data.

It wouldn't be very interesting if everyone stayed on topic. This is a discussion group. This is sci.electronics.DESIGN. Design implies a lot of meandering.

--
John Larkin         Highland Technology, Inc 

lunatic fringe electronics
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Reply to
John Larkin

learn how Usenet works, this isn't your Facebook wall, or Twitter (what's this "@" stuff?) I responded once to your original post the other replies were to other people.

Reply to
bitrex

He doesn't even understand how Usenet works but has "expectations"

Reply to
bitrex

You "resent" it? You "expect" answers to be what now? You show up like a noob from Google Groups five minutes ago with a bunch of demands dropping your credentials like anyone care. Who is even you?

OMG get a load of this guy. Get over yourself, sweetheart. You don't "own" a thread you start and nobody was even talking to you when it went off-topic.

Reply to
bitrex

** Would that include amplifiers made by Phase Linear, SAE, Crown, BGW, Yamaha etc ?

Worked on quite a few of them and can say what many of the house or "secret" part numbers are.

.... Phil

.... Phil

Reply to
Phil Allison

Though the function of many devices is, as you say, excellent, yet a few hours with a curve tracer is an important piece of experience to have. Watch a semiconductor overheat, make smoke, and then... see how it died (or how it recovers and continues to function when cooled).

When a transistor fails, it often passes the two-diodes testing, but a curve trace that shows it to have 6V breakdown instead of 80V, is giving you priceless information.

Yes, a curve tracer is an exploratory tool, and gives good service at the borders of the known. That may be RF, or it may be Zener noise, or it may be Early effect, or any of the characteristics that a design (or repair) will hinge on. Specification sheets just do NOT cover everything, it takes some exploration too.

Don't leave the well-blazed trail without your axe, compass, and curve tracer.

Reply to
whit3rd

So clearly you haven't bothered to read /any/ other threads in this group!

When wandering into a room/forum/group/etc it is considered wise to listen/read for a bit so that your contributions can "fit in" with other people's contributions.

If you can't stand the heat (and can't even remember to hit the "send" button"!), stay out of the kitchen.

Reply to
Tom Gardner

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