EMRFD Message Archive 14334
Message Date From Subject 14334 2017-09-19 08:12:15 ab7vf Curve Tracer So
I'm considering building a curve tracer .. What in (anyone's) opinion is a "good" range for the base step
current/ gate step voltages ..Small signal npn/pnp ..njfet mosfets
14335 2017-09-19 09:52:58 chuck adams Re: Curve Tracer I use
You can set the steps and ranges and you can save the
data in ASCII to your computer for plotting and analysis.
I use gnuplot to generate curves. I can come up with some
demos, if you like....
14336 2017-09-19 14:22:44 Mike Re: Curve Tracer Jim:
One of the on-line homebrew designs that I think might (at least
partially) meet your needs is the design provided in "Electronics World"
magazine for August 1971. This is available on-line (a google search on
"Electronics World Magazine Archive" should provide a link). This
design provides for base/gate drive steps of 2 uA to 1 mA/step for
bipolars and 0.2 V to 1.0 V/step for JFET's. Although I don't think it
directly addresses testing of MOSFET's. And this design uses 2n1671
unijunction transistors; I think the unijunction transistors could be
replaced with dual bipolar arrangements per Solid State Design for the
Radio Amateur pages 173-174.
I can provide a list of other on-line resources for homebrew curve
tracer designs if desired.
Mike Dinolfo N4MWP
14337 2017-09-19 17:56:23 jim Re: Curve Tracer
Thanks Chuck and Mike for the repliesI've got an op-amp based design (my first semi-original opamp effort) that I've glopped together as a first try .. It works, just trying to decidehow many ranges and values.I'm mostly hardware hacking and staying away from software solutions"americanradiohistory.com" has almost all the magazines for perusal and download.I've found that the ujt based ones are too tweaky for my tasteMore to come as the rainy season hitsThanks again, Jim
14338 2017-09-20 00:21:53 chuck adams Re: Curve Tracer Jim,
Good luck on the project. I got the Peak critter and I really love it.
I realize it isn't for every one.
14395 2017-10-20 16:14:29 neiperalta Re: Curve Tracer Is there any missing connection in the Electronics Now schematic?Where does the emioter current flow to the collector power supply?73 - LU5DNM 14396 2017-10-20 20:56:28 jim Re: Curve Tracer
14397 2017-10-21 09:11:05 Norberto Modanesi Re: Curve Tracer
Schematic you have mentioned in Electronics World. August 1971
14398 2017-10-21 21:45:15 jim Re: Curve Tracer
14399 2017-10-22 10:22:48 Norberto Modanesi Re: Curve Tracer
Yes. That is.
14400 2017-10-22 16:27:54 Jim Strohm Re: Curve Tracer Any chance that somebody can post that article to this group's file section along with a corrected schematic?Jim N6OTQ
14401 2017-10-22 18:13:53 K5ESS Re: Curve Tracer
Find it here;
14402 2017-10-22 23:02:08 jim Re: Curve Tracer
14407 2017-10-23 10:00:58 Norberto Modanesi Re: Curve Tracer
I think there is another mistake in the schematic. How the Ib polarity is changed when changing NPN/PNP?
Find it here;
14409 2017-10-23 22:01:21 jim Re: Curve Tracer
14411 2017-10-24 21:56:18 Jim Strohm Re: Curve Tracer Looks to me like the two unobtainium unijunction transistors serving as relaxation oscillators could be replaced by NE555 or equivalent without too much difficulty.And ... what were the corrections again? I haven't really been following this thread carefully.73Jim N6OTQ 14414 2017-10-26 00:54:40 gi0gdp Re: Curve Tracer As a side to this i have a very similar but simpler curve tracer from 1970 something that i built.It never really had a job until about 1985 when alot of surplus RF devices appeared here and whilstthey often where quoted as "25 watt FM" devices nobody had a clue as to what sort of Vce they had.Well the tracer sure shows it when at the end of the trace it goes vertical. Best of all calibration was deadeasy you just got say a MRF247 and looked to see the point at the end of the constant current line at which itwent vertical. Because it was all 50 Hz stuff there was no permanent damage.cheersGeoffGI0GDPBasically you could easily distinguish 28v devices from 13.8v ones 14418 2017-10-27 10:49:36 ab7vf Re: Curve Tracer Hello all
For your amusement/consideration, I posted a circuit diagram for collector ramp/base step generation in folder "curve tracer" based on op-amps
No unobtainum ujt's or that cruft ..I used lm158's cause thats what I had ..lm1458 did not work in the step-generator portion