Re: Curve Tracer vs. Octopus

Robert Simpson

This diode tracer is what I used to help find a bad diode in my 485 (photo folder 485 no trace).

--- In, Peter Gottlieb <hpnpilot@...> wrote:

Oh it's very simple. A small transformer and resistor and the scope in X-Y as
you say. I used to use (if my memory serves) a little Western Electric 2012B
wall wart transformer. Great for two terminal devices like diodes, MOVs and the
junctions of bipolar transistors. Will show you the Zener knew nicely too. Won't
do the curves for a transistor though, too crude for that, although you can rig
stuff up, either static or resistive-divider.


On 3/23/2013 7:50 PM, Rob wrote:

I have a fuzzy memory from back in my electronics days of a circuit called an
octopus. More or less involved 6-18Vac transformer, having the scope in X-Y
and then observing scope trace/lissajous patterns for various components. If I
remember correctly there was even a boutique industry that utilized the same
concept in that you could inject AC signal and then measure the pattern at
various places in the ckt to troubleshoot the piece of equipment. Kind of an
active troubleshooting mode. The company would publish schematics/tables with
the patterns and in this way greatly reduce troubleshooting time and/or
fiddling with high voltages and currents….. In any event, not posting to have
my memory corrected as it is certain that I am not doing justice and they are
20-30 year old memories….and the mom and pop shop I worked in never purchased

In any event, I am mostly curious because I have never had the opportunity (or
resources) to have a curve tracer. Does or would an octopus serve as a poor
man's curve tracer? I assume (that darn word) that a curve tracer is more of a
designers tool than a troubleshooting aid? Is my perception correct? I'm sure
it isn't as cut and dry as I indicate.

Biggest thing I am trying to ascertain is…due to cost curve tracer is low on
my wish list…. However, given the market price they consistently fetch I am
obviously missing something. Mostly looking for insight on what I am missing..
No doubt I could do research myself and likely answer most of my own
questions. However, that path would not capture the "in my opinion" factor I
have come to respect several associated with this forum for.

Thanks as always for the bandwidth



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