Re: zener diode

Allan Adler wrote:

I have what I believe is a zener diode. One end is red and the other end
is blue. What kind of zener diode is this and which end is which?
--
Ignorantly,
Allan Adler <ara@xxxxxxxxxxxxxxxxxxxx>
* Disclaimer: I am a guest and *not* a member of the MIT CSAIL. My actions and
* comments do not reflect in any way on MIT. Also, I am nowhere near Boston.


I don't recognize the color markings you describe but I've been inactive for
*a*long* time ... and at no time did I know everything. ;-)

Use a resistance meter to measure "front/back" resistance ratio. This tells you
which end is anode, which is cathode. Be sure you know the actual polarity (is
red positive? negative?) of your particular meter. My venerable old Simpson
269 puts positive on the red lead but I have seen meters that put positive on
the black lead. Also, take care not to use a resistance scale that could allow
a damaging amount of current to go to the diode.

Once you know which end of the diode is cathode, hook it up to a variable DC
source, forward biased, and through a series resistor (to limit the current).
Put a voltage meter across the diode and, starting at zero (0) volts, slowly
increase the voltage on your DC source while watching the voltmeter. When/if
you perceive a "knee", that is, the voltage increase across the diode is sharply
non-linear with respect to the increase in current through it, then you have
exceeded the breakdown, or "zener", voltage. Of course, if your zener happens
to be, e.g. an 80v one and your DC power source maxes out at less than 80v then
the diode won't "break down" and you won't see a knee; you'll have to use higher
voltage.
.

Relevant Pages

  • Re: Dumb "current transformer" questions
    ... I will use it for my phase converter. ... I have a DC current meter on the welder's panel. ... >>> Since the voltage reading is screwed up by the voltage drop of the ... >>> diode, I would need to find a diode with low voltage drop. ...
    (rec.crafts.metalworking)
  • Re: meter with continuity test and diode test on same setting
    ... the added meter changes the current supplied ... reading on the diode testing meter. ... I was not trying to check the accuracy so much as determine whether these two meters were displaying voltage or resistance. ... I think the voltage check proves that they are not displaying voltage, and the combination of voltage and current measurement confirms, pretty closely that these meters are displaying something close to resistance. ...
    (sci.electronics.basics)
  • Re: meter with continuity test and diode test on same setting
    ... the added meter changes the current supplied ... reading on the diode testing meter. ... I was not trying to check the accuracy so much as determine whether these two meters were displaying voltage or resistance. ... I think the voltage check proves that they are not displaying voltage, and the combination of voltage and current measurement confirms, pretty closely that these meters are displaying something close to resistance. ...
    (sci.electronics.basics)
  • Re: microwave high voltage ?s
    ... You cannot test the HV diode with your meter. ... enough break-over voltage to get the junction to properly conduct. ... It is best to use a proper HV diode tester to check this type of diode. ...
    (sci.electronics.repair)
  • Re: microwave high voltage ?s
    ... You cannot test the HV diode with your meter. ... enough break-over voltage to get the junction to properly conduct. ... It is best to use a proper HV diode tester to check this type of diode. ...
    (sci.electronics)