## #4 Zener Diode [Post Homework Here]

Talk about the third PyroEDU course here.
ThePyroElectro
Posts: 1181
Joined: Mon Nov 12, 2007 9:24 pm
Location: Earth
Contact:

### #4 Zener Diode [Post Homework Here]

A new lesson was posted today:
http://www.pyroelectro.com/edu/analog/zener_diode/

wr9h
Newbie Pyro
Posts: 12
Joined: Sat Nov 09, 2013 7:49 pm

### Re: #4 Zener Diode [Post Homework Here]

Lesson 4: Zener Diodes

Q1) What is unique attribute of every zener diode?
The zener "knee" voltage. A zener diode will allow current to flow (in both directions) through itself but only at a certain voltage and that is the knee voltage. The zener diode will maintain its knee voltage at a fixed level regardless of current flow or load current demands (within the diodes specifications). Another way of saying this is thus: the zener diode acts as a constant stable voltage source.

Q2) How is a zener diode different from a normal diode?
A zener diode allows current to flow pass through it in both directions! It also has a specific operating voltage (zener or knee voltage) that determines its operating point (located on the reverse bias portion of its IV curve).In addition when an AC signal is applied to a zener diode it will function as a normal diode (passing one peak of the AC signal while blocking the other...1/2 wave rectification) but with one more caveat: it will "clip" the passed signal peak at its (zener diode) operating (knee) voltage thereby providing a limited voltage output.

Q3) How could a zener diode be used to protect an input from a larger than expected voltage?
By placing zener diodes, in the proper configuration (usually in parallel with voltage source), at the voltage input of interest. The voltage will be limited to the zener voltage (the diodes operating point).
The major functions of a zener diode besides voltage protection is as low current voltage regulators and as sources of stable reference voltages.

Q4) Draw the circuit diagram of a battery, resistor, zener diode that provides an output at the zener's "knee" voltage.
I did this experiment as per the video and got 5.02 volts using a 100 ohm resistor. A resistor is placed in series with the battery and zener diode. Haven't figured out how to draw on here yet!!! Is there a way???

Great lesson and thanks for the course. Now it's onto filters. Goodie!!!

Herb

ThePyroElectro
Posts: 1181
Joined: Mon Nov 12, 2007 9:24 pm
Location: Earth
Contact:

### Re: #4 Zener Diode [Post Homework Here]

wr9h wrote:Lesson 4: Zener Diodes

Q1) What is unique attribute of every zener diode?
The zener "knee" voltage. A zener diode will allow current to flow (in both directions) through itself but only at a certain voltage and that is the knee voltage. The zener diode will maintain its knee voltage at a fixed level regardless of current flow or load current demands (within the diodes specifications). Another way of saying this is thus: the zener diode acts as a constant stable voltage source.

Q2) How is a zener diode different from a normal diode?
A zener diode allows current to flow pass through it in both directions! It also has a specific operating voltage (zener or knee voltage) that determines its operating point (located on the reverse bias portion of its IV curve).In addition when an AC signal is applied to a zener diode it will function as a normal diode (passing one peak of the AC signal while blocking the other...1/2 wave rectification) but with one more caveat: it will "clip" the passed signal peak at its (zener diode) operating (knee) voltage thereby providing a limited voltage output.

Q3) How could a zener diode be used to protect an input from a larger than expected voltage?
By placing zener diodes, in the proper configuration (usually in parallel with voltage source), at the voltage input of interest. The voltage will be limited to the zener voltage (the diodes operating point).
The major functions of a zener diode besides voltage protection is as low current voltage regulators and as sources of stable reference voltages.

Q4) Draw the circuit diagram of a battery, resistor, zener diode that provides an output at the zener's "knee" voltage.
I did this experiment as per the video and got 5.02 volts using a 100 ohm resistor. A resistor is placed in series with the battery and zener diode. Haven't figured out how to draw on here yet!!! Is there a way???

Great lesson and thanks for the course. Now it's onto filters. Goodie!!!

Herb

Hello,

All correct answers! Filters is where the fun begins (in my opinion). I find diodes a little more on the boring side .

Some people draw it out by hand, scan it and then upload it to the forums in a post. You could give that a shot.