To share a comment string with you two gentlemen is something I could not pass up. Thank you both for making the most exceptionally educational videos on the Internet.
Now I know why i have seen zeners in series as a reference in older schematics they are trying to cancel the opposite temperature Coefficient for a more stable reference... love your vids Allan one of the best channels on yt.. your knowledge and aptitude for passing it on is really commendable.. you take the time to pass on with no real reward other than the knowledge you have helped others.. our society grows great thanks to folk of your calibre Thank you so much
This is the best tutorial on Zener Diodes I have ever seen. Was going to rate it 10 out of 10 then I saw you included the notes as a PDF. So now it is 11 out of 10. Thanks so much for the perfect demonstration.
WOW. I miss these back to basics video topics. I never knew there were zeners and avalanche (zener) diodes. You ALWAYS teach something that is not generally taught in regular electronics courses or general articles. I guess I need to buy some good components from Digikey and test this myself. The chinesium devices are OK but that avalanche knee is incredible and a very desirable effect. I had no idea. THANK YOU MAESTRO.
Outstanding vid and teaching. Zener diodes are often used in the design of Intrinsic Safety, where a circuit has to be used in a Hazardous location and the voltage MUST be controlled to never go beyond a certain amount.
I’ve been catching up on your nearly 300 videos. I must say what a tremendous pleasure it is to watch a consummate professional with superb teaching skills. I so appreciate your concise, organized, brilliantly presented lessons, focused on the topic without distraction or drama. When I go sit down with my antique Tek equipment to enact your examples, I feel like I’ve been working there. This was never my field, but I’ve learned more theory and fundamentals-with clear understanding-in two weeks than I did in 40 years of dabbling. From one Alan E to another, you have my gratitude. Many thanks.
Alan, When you published your step voltage generator video I knew a curve tracer was next. If i recall our email exchange correctly you mentioned you did not have a commercial curve tracer. So congratulations on the 576 acquisition, Once again, if i remember the conversation correctly. None-the-less, great video lesson. Having the right instructor with the right equipment to demonstrate the subject is priceless. 73, Paul, W1SEX
@@w2aew Yeditepe University in Turkey, Introduction to Electronics course. He put your "Op Amp Power Supply Considerations" video as a tutorial for the Virtual Ground concept in one of our lab papers and i decided to check out more videos :P
Thanks again AEW. For me, not being technically educated, your explanations are very clear and to the point. I keep all your info printed on my desk and work with it. Keeps me going in the hobby on my age.
Al, you are a really good teacher. Info is simple and easy to understand. All your videos and great but I especially like your back to basic and circuit fun videos. Thank you. 73, Christian, VE2MW
As you implied, the temperature stability depends on the break through voltage. The 5.2V Diodes are very stable as they tend to have a combined coefficient of zero.
I have an undergrad in EE and I often learn a little something from your back to basic videos. You always do such a good job with these type videos, if you are not careful people might start to think that you are a nice guy :o) Thanks for sharing and keep out the good work. 73
Great video....!! Having been an electrical engineer for the past 30 years, it is still so wonderful to find someone who can teach the basics in a way that interests all levels simultaneously. Just fantastic work indeed.! Having found my way here from Hack-A-Day(best website ever..!).....I am blessed to see this is tutorial #289.....meaning I have found a new source for lunchtime instruction.....Great Job....looking forward to video #500.
Aha! So the balancing of the positive and negative temperature coefficients is what's used to make the temperature-stable Zener that you use as a voltage reference in your 50 microamp current source, handy for calibrating Simpson 260's! Love it!
I just discovered your channel few days ago, looking how to re-calibrate an old Tek 465 I purchased from eBay. I had this scope on my bench at work, in Romania, from 1988 to 1995, a great scope. You're a very talented teacher. Thank you for everything you do. Myself been a HAM since 1985, 73s Catalin YO3FCU.
Alan, excellent presentation as usual! I had long forgotten about the term avalanche diode and the difference between true zener and avalanche diode. Thanks for knocking off some of the cobwebs in my old brain. I truly enjoy your videos.
Deeply appreciate you sharing your knowledge. You have a talent for explanation, also excellent hand drawings. Next time you think to yourself 'shall I make a video?' i want you to know how much this was appreciated. Well edited, too; no fat on the bone, but decently comprehensive
Zener sounds like Zehner in german. And Zehner contains Zehn = ten. So, our trainer always said: design Z-Diode bias resistors, that at least 10mA current runs through the diode ;)
Your videos are always excellent, well explained all around. Thanks a lot! Please keep on coming. These back to the basics are a great idea. I'll try not to miss any of them.
Thanks! I plan to do a lot more with the curve tracer. It's really surprising how different a switching diode looks from a schottky diode, from a Ge diode, etc. Plus, makes transistor matching a lot more comprehensive.
Really excellent video - your drawings made it so clear - I didn't realize there was a difference between the types of the generic name of 'zener diode'.
Excellent video sir! This is a very insightful video about the zener diode. With the illustrations on the curve tracer made it even more clear. Thank you very much for this lesson. I like your videos a lot, you are an excellent teacher.
Hello Allen. My condolences for your loss of your father. Great video again.I have learned from watching it (Avalach effect, heavy /light doping). A nice follow up to this video could be the "variable voltage Zener diode" ( Zener conected to non inv. input op-amp with neg. feedback of 2 voltage divider resistors connected to the inv. input ) which is met in countless circuits as the LM431.
I always wondered why would anyone use a voltage divider and a zener diode instead of just a zener diode for voltage reference. Now i know! Very good video, thanks!
thanks for the video. very well explained! no questions remain to be asked :) now please do a part 2 on how to use voltage reference circuits using cheap npn bjt/mosfet using zerner or other techniques. thank you very much!
the sharpness difference was striking, when you have an electric spark from a capacitor you get an extremely sharp turn on that can be easily compared to the avalanche effect imo. If you wanted to create a good electronic analogy to a spark gap, an avalanche diode combined with a power transistor should do the job well.
whoa... synchronicity I had just bought a couple of zeners a week ago or so but they didn't work as I expected so I put them away till better times now I know what my mistake was (too large series resistor)
Do a video lesson about precision voltage reference IC chips because they have a zener diode but also they use an IC op amp to compare the voltage. If you look at the datasheets of various precision voltage reference components because they can be used as a voltage regulator. I'm not sure what the capacitance loading has to be before the output pin starts to be unstable
Good video. I only missed the fact that zener diodes can be noisy. Especially above 5-6V. Makes you wonder if the construction of avalanche diodes is inherent to more noise?
The avalanche breakdown itself tends to be inherently noisy. That's annoying in some applications, but when you need a noise source (eg for a random number generator) it's very handy.
In my high voltage leakage tester project (the final, part 7 is scheduled to be published on Saturday morning), I was using 5.1 zeners as voltage clamps on the input of the Arduino’s analog inputs. These were protection I n case of a over voltage from the resistor dividers (it measures the supply and DUT voltages, over 400VDC), or over current through the current shunt causing the input voltage to go over 5v, but they were conducting too soon and were affecting the voltage readings as they then effectively became resistors within the resistor divider, preventing predictable divider ratios for accurate measurements, worked fine without them. Time to try some different ones.
I use zeners for very loose tolerance voltage regulation. I use a TL431 for precision poor mans programmable voltage standard. They are precise and cheap. I always skavange them from items I take apart for parts. I always use them for the reference voltage for a voltage comparator circuits when used on a varying power supply voltage. ie: battery chargers that use a voltage reference for completed charge level indication for auto shut off. Look up the data sheet and you will be impressed with its functionality and its various application circuits they use them with. Enjoy.
Cool! I can start watching them now. I didn’t want to watch some then forget the first ones before I got to the end! Someone else I find easy to understand and interesting too. Can’t wait to see the tester finished now! 🙂
Another great video! I wonder about the capacitance characteristics between the two types and also under various biasing situations. I know that you already did a varactor diode video.
Incredible video. But does this mean that the schematic symbol of zener diodes below 5 or 6 V will be opposite to the usage of an avalanche one above that? (because in the video you still shows the P-N junction like a normal diode would be, for the avalanche style, with the difference being very lightly doped in comparison) Really interesting stuff!!!
If you have the time a tutorial of an output pin of a microcontroller would be great . They seem to have a Pmos and Nmos on the internal drive , BUT if you look at the I/V curves the calcs show a ~54 ohm Rds on of the Pmos and ~ 18 ohms of the Nmos. If you try and simulate with LTspice the mosfets have rds On in the order of < 2 ohms . The trouble I have is how the voltage drops on the output pin as the current increases . Allthough datasheets show up to 25mA source / sink per pin once you are > 6-8ma things go pear shape. Driving into a capacitive load seems to be a no no as a short pulse on the output into a cap of a few pF results in I=dv/dt so with a short pulse the I is way bigger than what can be delivered and the pulse " disappears" - Apologies I did not know where to put this request but hopefully you will get time to address this .
I can add this to my list of future topics. I will say now that it is quite likely that the models used in your LTSpice spice don't accurately model the characteristics of the PMOS and NMOS devices in your micro. The characteristics of the devices used in an integrated device will often differ greatly from the characteristics of discrete devices. So, unless you have access to model parameters that are specific to the process used in the manufacture of the micro, then the simulation results are likely going to show non-realistic results.
w2aew thanks . I did model on ltspice with 2 switches with some progress but my 61 year old cranium is loosing dielectric so not performing as expected . I can send ltspice model to an email address.
Thank you, maybe explore the AC response of the zener as well, another future video I'd love to see by you would be one on voltage references (resistor-zener / JFET-zener / TL431)
Why don't they break? Something to do with the length of the depletion region? It is amazing that they can take much power without changing or burning.
Large Zener voltage does not mean large power. Power is the product of voltage across the device multiplied by the current through it. It is important to limit the current (forward or reverse/zener) to keep the power dissipation within the rating for the device.
Reverse voltage of less than 5V isn't really sufficient for avalanche mode operation, so devices are designed with highly doped materials for Zener breakdown. At higher voltage, avalanche mode generally provides better/sharper breakdown characteristics.
Can you explain how your equipment works that traces the two curves at once? I’m confused on what I’m looking at. You’re tracing the positive voltage and negative voltage lines at the same time, I think I’m lost on what it means to be reversed biased
Thank you. Would you be open to do a kind of review? pros & cons? A little off topic but I'd be very happy to see how usability works out. Reviews on a***n aren't too frantic..
Quick review... Pros: lightweight, great battery life, seamless cloud storage, PC app to access files and export PDF or PNG, responsive, good paper & pencil feel, lots of pen/pencil/marker/brush selections, editing/moving works well. Cons: Very expensive, no case/folio included - so nothing to hold the special stylus, the folio they sell is very pricey (found a cheaper one on Ama*on), PDF files are large and take a long time to print.
Thank you. Your input is appreciated. Issues w/ system stability/reliability? Data loss when transfering? Delay when opening large PDFs? Reading comfort/tools?
I've had no problems with stability - never crashed or hung. Never lost data during transfer (it transfers to the cloud in the background). I haven't used it to open large PDFs and annotate them, so I really can't comment on that. I've only used it for creating my notes pages for a couple of videos so far. The display isn't "paper white", it is a little dim/gray, but looks great in good room light. With dim lighting, it is just OK.
Is the breakdown of a "normal" diode one of those two effects (avalanche most likely), just that it destroys the diode in the process, or is there a third mechanism for reverse conducting? Could you say that every silicon diode is an avalanche diode, but some can do it only once at a not well defined voltage? ;)
I believe that the breakdown of "normal" diodes is typically avalanche. There may be other breakdown mechanisms (arc'ing over, etc.). The reason why breakdown *can* be destructive is because often there isn't anything that limits the current.
ALWAYS fantastic videos! By the way, can I use a Tektronix 1910 sig gen for repairing vintage radios, receivers, guitar amps? Can it be modified for that purpose? The 1910 is sex-on-a-stick! Any advice from anyone would be greatly appreciated. Thanks!
w2aew Yes, of course, you're right. I've been seeing working 1910s on eBay under $100 delivered. State of the art Tektronix... It would look great on my kitchen table! I guess I'll just have to stick with my PILCO 7070. If you have any suggestions regarding a 70's ~ 90's Tektronix Sig Gen that can be had for under $100? Let me know. Thanks so much for the reply back. It felt like I got a letter from Elvis.
Hi, i built a clipping circuit using opamp and 4.7v zener diode and i use a sinusoidal signal at the input (1khz). The top of the signal crest at the output is not flat but rounded. Is it caused by the fact that you tell in the video? Thank
I never knew that "zener" diodes above 5V were actually avalanche. So interesting. Thanks for the video!
Thanks Ben - I always feel honored when I can teach *you* something!
To share a comment string with you two gentlemen is something I could not pass up. Thank you both for making the most exceptionally educational videos on the Internet.
Thank you for being a loyal viewer!
Nice breakfast ✅ detailed zener explorations ✅ good start of the day!
Now I know why i have seen zeners in series as a reference in older schematics they are trying to cancel the opposite temperature Coefficient for a more stable reference... love your vids Allan one of the best channels on yt.. your knowledge and aptitude for passing it on is really commendable.. you take the time to pass on with no real reward other than the knowledge you have helped others.. our society grows great thanks to folk of your calibre Thank you so much
This is the best tutorial on Zener Diodes I have ever seen.
Was going to rate it 10 out of 10 then I saw you included the notes as a PDF.
So now it is 11 out of 10. Thanks so much for the perfect demonstration.
Who knew you could almost base an entire physics career on diode design, application and theory.
WOW. I miss these back to basics video topics. I never knew there were zeners and avalanche (zener) diodes. You ALWAYS teach something that is not generally taught in regular electronics courses or general articles. I guess I need to buy some good components from Digikey and test this myself. The chinesium devices are OK but that avalanche knee is incredible and a very desirable effect. I had no idea. THANK YOU MAESTRO.
Outstanding vid and teaching. Zener diodes are often used in the design of Intrinsic Safety, where a circuit has to be used in a Hazardous location and the voltage MUST be controlled to never go beyond a certain amount.
I’ve been catching up on your nearly 300 videos. I must say what a tremendous pleasure it is to watch a consummate professional with superb teaching skills. I so appreciate your concise, organized, brilliantly presented lessons, focused on the topic without distraction or drama. When I go sit down with my antique Tek equipment to enact your examples, I feel like I’ve been working there. This was never my field, but I’ve learned more theory and fundamentals-with clear understanding-in two weeks than I did in 40 years of dabbling. From one Alan E to another, you have my gratitude. Many thanks.
Could not have been explained any better. Excellent.
Alan, When you published your step voltage generator video I knew a curve tracer was next. If i recall our email exchange correctly you mentioned you did not have a commercial curve tracer. So congratulations on the 576 acquisition, Once again, if i remember the conversation correctly. None-the-less, great video lesson. Having the right instructor with the right equipment to demonstrate the subject is priceless. 73, Paul, W1SEX
Yes, I was lucky to get this one earlier this summer - only needed a few small repairs.
Big love to my teacher for showing me this channel, these videos are really helpful, thanks ^^
Very nice! I wonder where you're going to school (i.e. what teachers are sharing my channel?)
@@w2aew Yeditepe University in Turkey, Introduction to Electronics course. He put your "Op Amp Power Supply Considerations" video as a tutorial for the Virtual Ground concept in one of our lab papers and i decided to check out more videos :P
@@Lunamana That is great! So happy to hear that my videos are helping the next generation of engineers!
I’m in love with that Curve Tracer! That Vert/Div, Horiz/Div display 😍
Super interesting video! Thanks for this!
The numbers are from an array of fiber optic cables running back to an array of incandescent bulbs!
I watch as many electronic chanels as I can but you Alan are the number ONE, Thanks so much👍👍👍
Very much appreciate you taking the time to show a demonstration rather than simulations and drawings.
Again, the best explanation I have ever had. Thank you
Thanks again AEW. For me, not being technically educated, your explanations are very clear and to the point. I keep all your info printed on my desk and work with it. Keeps me going in the hobby on my age.
Great to see a working 576 in action!
Al, you are a really good teacher. Info is simple and easy to understand. All your videos and great but I especially like your back to basic and circuit fun videos. Thank you.
73, Christian, VE2MW
As you implied, the temperature stability depends on the break through voltage.
The 5.2V Diodes are very stable as they tend to have a combined coefficient of zero.
I have an undergrad in EE and I often learn a little something from your back to basic videos. You always do such a good job with these type videos, if you are not careful people might start to think that you are a nice guy :o) Thanks for sharing and keep out the good work. 73
Excellent work Alan, thanks, simple, clear explanation with quality practical demo.... Perfect combination....
Excellent, again! Love the way you combine theory and practical demonstrations.
Great video....!! Having been an electrical engineer for the past 30 years, it is still so wonderful to find someone who can teach the basics in a way that interests all levels simultaneously. Just fantastic work indeed.! Having found my way here from Hack-A-Day(best website ever..!).....I am blessed to see this is tutorial #289.....meaning I have found a new source for lunchtime instruction.....Great Job....looking forward to video #500.
Thanks. I hope you enjoy the rest of my videos just as much.
Aha! So the balancing of the positive and negative temperature coefficients is what's used to make the temperature-stable Zener that you use as a voltage reference in your 50 microamp current source, handy for calibrating Simpson 260's! Love it!
I just discovered your channel few days ago, looking how to re-calibrate an old Tek 465 I purchased from eBay. I had this scope on my bench at work, in Romania, from 1988 to 1995, a great scope. You're a very talented teacher. Thank you for everything you do. Myself been a HAM since 1985, 73s Catalin YO3FCU.
this little difference is never shown on books i read, thanx!
U teach like a pro please keep up this work for our sake
Oh that probe compensation screwdriver is just golden :) Great video Alan! Thank you and keep it up!
Alan, excellent presentation as usual! I had long forgotten about the term avalanche diode and the difference between true zener and avalanche diode. Thanks for knocking off some of the cobwebs in my old brain. I truly enjoy your videos.
Holy breakdown Batman that was an absolutely fantastic video
Deeply appreciate you sharing your knowledge. You have a talent for explanation, also excellent hand drawings. Next time you think to yourself 'shall I make a video?' i want you to know how much this was appreciated. Well edited, too; no fat on the bone, but decently comprehensive
Zener sounds like Zehner in german. And Zehner contains Zehn = ten. So, our trainer always said: design Z-Diode bias resistors, that at least 10mA current runs through the diode ;)
Handy tip!
Kudos for the diplomatic pronunciation correction :D
I always learn something from your videos. Diodes were always a mystery to me but now....wow, eyes opened. Thank you Alan. 73 de N0BPS
thanks alan for back to basics. I love it
Now I know how they work :)
Be great to see a voltage regulator circuit with a Zener in it.
Your videos are always excellent, well explained all around.
Thanks a lot!
Please keep on coming. These back to the basics are a great idea. I'll try not to miss any of them.
Thanks for this nice video. TVS diodes are just a fancy name for an avalanche diode.
Excellent video. I learn something new with every of your videos.. Thank you.
Great review Alan...having the curve tracer for display really drives the point home. 73 - Dino KL0S
Thanks! I plan to do a lot more with the curve tracer. It's really surprising how different a switching diode looks from a schottky diode, from a Ge diode, etc. Plus, makes transistor matching a lot more comprehensive.
I always look forward to another edition of your Back To Basics lessons.
Thanks Alan,
Dave
You do this so well and are a pleasure to listen to.
Really excellent video - your drawings made it so clear - I didn't realize there was a difference between the types of the generic name of 'zener diode'.
I like your headings on the notebook with a kind of meteor underline--I've never noticed that before... anyway a great video as always!!
That was a new little bit of flair... ;-)
Thank you for doing these videos you are an excellent teacher! Explained in a clear and concise manner.
Thanks again for another really great video, Alan. I always learn a lot from your videos. Greetings again from Melbourne, Australia.
Excellent video sir! This is a very insightful video about the zener diode. With the illustrations on the curve tracer made it even more clear. Thank you very much for this lesson. I like your videos a lot, you are an excellent teacher.
Hello Allen. My condolences for your loss of your father. Great video again.I have learned from watching it (Avalach effect, heavy /light doping). A nice follow up to this video could be the "variable voltage Zener diode" ( Zener conected to non inv. input op-amp with neg. feedback of 2 voltage divider resistors connected to the inv. input ) which is met in countless circuits as the LM431.
Nice video! You have a very easy to follow/understand teaching style.
Thanks for sharing some of your knowledge with us. 👍🏼
Thanks Alan. Love your videos. You are a great teacher!
Excellent explanation of the zener diode thank you very much
Great video Alan. Good use for your new curve tracer too.
Excellent lesson, well explained. I cans also see you have mastered the tablet!! Thanks Alan
fantastic video
Very helpful. ANd a wonderfully clear explanation.
I love your videos, you do such a great job at presenting the information.
Peace and blessings 🙌
Thanks. Your videos helped in experimental understanding.
Nice 576 and good video. Thanks Alan.
Thanks for share.
73 PU2SRZ - Sao Paulo - Brasil
I always wondered why would anyone use a voltage divider and a zener diode instead of just a zener diode for voltage reference. Now i know! Very good video, thanks!
That's some great educational material.
Nice lesson Alan, thanks!
Useful video
Thanks for the tutorial 😀
Cool video...now I wanna buy a curve tracer and just play with my diodes i have lying around. 😁😁
bkrgls If you have a 2-channel scope with XY mode you can build a basic curve tracer. Look up IV curve tracer or octopus curve tracer circuits
epakai
Hey thanks for that piece of information. I'll look it up. 👍
In fact Alan covered this very topic!
th-cam.com/video/WWY-pakm_OM/w-d-xo.html
Thanks Alan, as usual!
More back to basics please.
thanks for the video. very well explained! no questions remain to be asked :) now please do a part 2 on how to use voltage reference circuits using cheap npn bjt/mosfet using zerner or other techniques. thank you very much!
the sharpness difference was striking, when you have an electric spark from a capacitor you get an extremely sharp turn on that can be easily compared to the avalanche effect imo.
If you wanted to create a good electronic analogy to a spark gap, an avalanche diode combined with a power transistor should do the job well.
still learning! :)
whoa... synchronicity
I had just bought a couple of zeners a week ago or so but they didn't work as I expected so I put them away till better times
now I know what my mistake was (too large series resistor)
Nice demonstration.
Hi Alan, you could have shown the temperature co-efficient impact on the IV curve by heating up and cooling down the diodes.
Thank you so much!
Very well done. Thank you.
Do a video lesson about precision voltage reference IC chips because they have a zener diode but also they use an IC op amp to compare the voltage. If you look at the datasheets of various precision voltage reference components because they can be used as a voltage regulator. I'm not sure what the capacitance loading has to be before the output pin starts to be unstable
Thank you Sir. Terrific keep it up.
Love your work!
amazing as usual
keep forward please
Well I learned quite a bit... 😀
Excellent!
Good video.
I only missed the fact that zener diodes can be noisy. Especially above 5-6V. Makes you wonder if the construction of avalanche diodes is inherent to more noise?
The avalanche breakdown itself tends to be inherently noisy. That's annoying in some applications, but when you need a noise source (eg for a random number generator) it's very handy.
You're right, I didn't cover the noise characteristics of them.
Another option is using normal diodes or LEDs in series
In my high voltage leakage tester project (the final, part 7 is scheduled to be published on Saturday morning), I was using 5.1 zeners as voltage clamps on the input of the Arduino’s analog inputs. These were protection I n case of a over voltage from the resistor dividers (it measures the supply and DUT voltages, over 400VDC), or over current through the current shunt causing the input voltage to go over 5v, but they were conducting too soon and were affecting the voltage readings as they then effectively became resistors within the resistor divider, preventing predictable divider ratios for accurate measurements, worked fine without them. Time to try some different ones.
I use zeners for very loose tolerance voltage regulation. I use a TL431 for precision poor mans programmable voltage standard. They are precise and cheap. I always skavange them from items I take apart for parts. I always use them for the reference voltage for a voltage comparator circuits when used on a varying power supply voltage. ie: battery chargers that use a voltage reference for completed charge level indication for auto shut off. Look up the data sheet and you will be impressed with its functionality and its various application circuits they use them with. Enjoy.
Cool! I can start watching them now.
I didn’t want to watch some then forget the first ones before I got to the end!
Someone else I find easy to understand and interesting too.
Can’t wait to see the tester finished now! 🙂
Try using a series regulator (add an emitter follower to the shunt regulator). That can vastly improve performance.
Another great video! I wonder about the capacitance characteristics between the two types and also under various biasing situations. I know that you already did a varactor diode video.
Incredible video. But does this mean that the schematic symbol of zener diodes below 5 or 6 V will be opposite to the usage of an avalanche one above that? (because in the video you still shows the P-N junction like a normal diode would be, for the avalanche style, with the difference being very lightly doped in comparison)
Really interesting stuff!!!
If you have the time a tutorial of an output pin of a microcontroller would be great . They seem to have a Pmos and Nmos on the internal drive , BUT if you look at the I/V curves the calcs show a ~54 ohm Rds on of the Pmos and ~ 18 ohms of the Nmos. If you try and simulate with LTspice the mosfets have rds On in the order of < 2 ohms . The trouble I have is how the voltage drops on the output pin as the current increases . Allthough datasheets show up to 25mA source / sink per pin once you are > 6-8ma things go pear shape. Driving into a capacitive load seems to be a no no as a short pulse on the output into a cap of a few pF results in I=dv/dt so with a short pulse the I is way bigger than what can be delivered and the pulse " disappears" - Apologies I did not know where to put this request but hopefully you will get time to address this .
I can add this to my list of future topics. I will say now that it is quite likely that the models used in your LTSpice spice don't accurately model the characteristics of the PMOS and NMOS devices in your micro. The characteristics of the devices used in an integrated device will often differ greatly from the characteristics of discrete devices. So, unless you have access to model parameters that are specific to the process used in the manufacture of the micro, then the simulation results are likely going to show non-realistic results.
w2aew thanks . I did model on ltspice with 2 switches with some progress but my 61 year old cranium is loosing dielectric so not performing as expected . I can send ltspice model to an email address.
Awesome...cheers.
nice review
Great video, I was waiting for more bench tests on the temperature coefficient but thanks anyways.
also the link to the notes seems to have a problem.
Thanks - I"ll have to explore the tempco characteristics in a future video. The notes link should work ok now.
Thank you, maybe explore the AC response of the zener as well, another future video I'd love to see by you would be one on voltage references (resistor-zener / JFET-zener / TL431)
Was that a 6X4W on your bench? Never knew about the avalanche diodes. Thanks for sharing. 73's
I think that's what's in that box...
Great, great...
Why don't they break? Something to do with the length of the depletion region?
It is amazing that they can take much power without changing or burning.
Large Zener voltage does not mean large power. Power is the product of voltage across the device multiplied by the current through it. It is important to limit the current (forward or reverse/zener) to keep the power dissipation within the rating for the device.
@@w2aew There are Z-D with 1.5kW impulse rating. I have seen TVS Diodes that still worked after desoldering themselves.
Well explained but why aren't all zener diodes avalanche type or true zener type?
Reverse voltage of less than 5V isn't really sufficient for avalanche mode operation, so devices are designed with highly doped materials for Zener breakdown. At higher voltage, avalanche mode generally provides better/sharper breakdown characteristics.
Can you explain how your equipment works that traces the two curves at once? I’m confused on what I’m looking at. You’re tracing the positive voltage and negative voltage lines at the same time, I think I’m lost on what it means to be reversed biased
The Curve Tracer that I am using applied a sinusoidal voltage to the zener diode. This voltage swings positive then negative and repeats.
Alan, thanks for this back to basics. I love the series.
What reader or tablet are you using for your notes in the videos?
It is from remarkable.com
Thank you. Would you be open to do a kind of review? pros & cons? A little off topic but I'd be very happy to see how usability works out. Reviews on a***n aren't too frantic..
Quick review... Pros: lightweight, great battery life, seamless cloud storage, PC app to access files and export PDF or PNG, responsive, good paper & pencil feel, lots of pen/pencil/marker/brush selections, editing/moving works well. Cons: Very expensive, no case/folio included - so nothing to hold the special stylus, the folio they sell is very pricey (found a cheaper one on Ama*on), PDF files are large and take a long time to print.
Thank you. Your input is appreciated.
Issues w/ system stability/reliability? Data loss when transfering? Delay when opening large PDFs? Reading comfort/tools?
I've had no problems with stability - never crashed or hung. Never lost data during transfer (it transfers to the cloud in the background). I haven't used it to open large PDFs and annotate them, so I really can't comment on that. I've only used it for creating my notes pages for a couple of videos so far. The display isn't "paper white", it is a little dim/gray, but looks great in good room light. With dim lighting, it is just OK.
Is the breakdown of a "normal" diode one of those two effects (avalanche most likely), just that it destroys the diode in the process, or is there a third mechanism for reverse conducting? Could you say that every silicon diode is an avalanche diode, but some can do it only once at a not well defined voltage? ;)
I believe that the breakdown of "normal" diodes is typically avalanche. There may be other breakdown mechanisms (arc'ing over, etc.). The reason why breakdown *can* be destructive is because often there isn't anything that limits the current.
can you do a video on time gating??
Can you be more specific? Time gating can mean a lot of different things.
Zeners in the DC world make sense. If we apply AC, is there a frequency dependence in their performance?
They can work as clamps, but are not lightning fast (few hundred ns switching speed)
Since avalanche diodes have sharper turning point, is there any benefit of using regular zener diodes? Besides balance out the temperature coefficient
Often you don't have a choice, depending on the voltage you need.
w2aew Got it. Thank you! I learned so much from you.
ALWAYS fantastic videos! By the way, can I use a Tektronix 1910 sig gen for repairing vintage radios, receivers, guitar amps? Can it be modified for that purpose? The 1910 is sex-on-a-stick! Any advice from anyone would be greatly appreciated. Thanks!
I believe that the 1910 is an NTSC composite video signal generator - not suitable for radio, receiver or guitar amp repair.
w2aew Yes, of course, you're right. I've been seeing working 1910s on eBay under $100 delivered. State of the art Tektronix... It would look great on my kitchen table! I guess I'll just have to stick with my PILCO 7070. If you have any suggestions regarding a 70's ~ 90's Tektronix Sig Gen that can be had for under $100? Let me know. Thanks so much for the reply back. It felt like I got a letter from Elvis.
the thing that you are showing the drawings on ... what is that, some sort of epaper drawing pad? great video btw
Yes, it is an epaper tablet from www.remarkable.com
Hi, i built a clipping circuit using opamp and 4.7v zener diode and i use a sinusoidal signal at the input (1khz). The top of the signal crest at the output is not flat but rounded. Is it caused by the fact that you tell in the video? Thank
Without seeing your circuit, it is impossible for me to say.
Here it's not possible to load a video or photo. I'm trying to understand how to.