Zener Diode Identification and Uses.
A zener diode is a silicon diode that is optimized to work in what
is known as the breakdown region.
This means that hey are able to when they are reverse-biased.
This is unlike normal which will self-destruct.
A zener diode’s breakdown voltages can range from 2 to 200 volts, making it
useful in a variety of applications.
One popular usage is of a voltage regulator.
This is due to the zener’s ability to maintain constant output voltages when
there are current changes in the circuit.
This makes zeners ideal as inputs to other or as voltage references for op-amps.
Testing.
Zeners are tested the same you would a regular diode.
To recall, diodes behave like a switch that is open in one
direction but closed in the other.
Before testing, make sure that the is placed on the diode setting.
Measure the forward-biased voltage of the diode by placing the positive or red lead
of the multimeter on the diode’s anode part.
This is the side of zener that is unmarked.
The negative or black lead of the multimeter should be on the cathode
or marked side of the diode.
A forward-biased silicon diode should read 0.5 to 0.7 volts, so this is the
reading you should see for the zener.
To test the reverse-biased switch the multimeter leads.
The multimeter should indicate an overload or no voltage drop, indicating
no current flow or infinite resistance.
Identification.
Zeners may be indistinguishable regular diodes.
Zener diodes may have a dark plastic casing with a dark stripe, which is the
same coloring as that of other diodes.
Many other zener diodes are copper colored, and are enclosed in a glass casing
with a white or black or blue stripe.
Still others may have metal casings.
If the diode is loose and you don’t have the package, find the
number that is on the casing.
For example, it may be 1N4734A or 1N751.
This is enough information for you to do search using your favorite search engine.
Another method is go directly to a manufacturer’s or distributor’s website
such as Fairchild Semiconductor or Newark, and look for the component there.
Sometimes the diode is not loose, is soldered to a circuit board.
It may be soldered in such a way you are unable to see the number.
In cases like this, look to see if the diode symbol is displayed on the board.
The symbol is the same as that of a regular diode, save that the
bar representing the cathode has extra lines that point up and down.