1V zener diode doesn't even break down at 5V! - Page 1
Forum section: electronics / beginners

author: vortexnl
author_rank: Contributor
timestamp: January 09, 2013, 07:07:23 pm
content: I ordered a 1V zener diode from Conrad but it doesn't work for some reason. I'm powering my project using 5V but when I put the zener in backwards no current will flow even when I don't use any resistors at all! When I put it in forward bias it just drops 600-700mV...Datasheet:http://www.produktinfo.conrad.com/datenblaetter/175000-199999/180505-da-01-de-Zenerdiode_ZPY_1_V.pdfAm I doing something wrong here?Thanks in advance,Nick

author: Bored@Work
author_rank: Super Contributor
timestamp: January 09, 2013, 07:26:05 pm
content: You don't get zener diodes that low. What you have is a normal diode intended to operate in forward direction, sold as a "zener diode".

author: olsenn
author_rank: Frequent Contributor
timestamp: January 09, 2013, 07:28:38 pm
content: I'm guessing it's a 1 Watt rated zener diode and 1V is just a typo for 1W

author: vortexnl
author_rank: Contributor
timestamp: January 09, 2013, 07:36:36 pm
content: Well this is odd I tested all 5 of the 'zener' diodes I ordered, but one of them actually had a break down voltage of 900mV! This is kinda odd. If there are no zener diodes rated for 1V then conrad is just being naughty because they literally stated it had a 1V breakdown...

author: olsenn
author_rank: Frequent Contributor
timestamp: January 09, 2013, 07:39:21 pm
content: I'm assuming you're measuring the reverse (break-down) voltage and not the forward voltage drop? Just checking.

author: vortexnl
author_rank: Contributor
timestamp: January 09, 2013, 07:42:42 pm
content: Yes, I'm testing the reverse breakdown voltage. I guess this wasn't the best order I did on conrad. Do you guys know if it's a good idea to get a decent voltage reference by just forward biasing the diode?

author: vortexnl
author_rank: Contributor
timestamp: January 09, 2013, 07:46:02 pm
content: Just to clarify, this is literally what you see when you browse the zener diodes on conrad...

author: Bored@Work
author_rank: Super Contributor
timestamp: January 09, 2013, 07:47:50 pm
content: Quote from: vortexnl on January 09, 2013, 07:42:42 pmThey are meant to be operated in forward direction, and will typically exebit the behavior as specified in the data sheet. If that specified behavior matches your definition of "decent" the answer is yes.

author: SeanB
author_rank: Super Contributor
timestamp: January 09, 2013, 07:48:11 pm
content: The "1V" is a silicon diode run in forward conduction. Tip is the voltage drop is the same as a lightly doped diode. The one breaking at a low reverse voltage is probably a faulty one that has contaminants on the die causing this. Not found in test as they are not tested at any reverse voltage at all.

author: vortexnl
author_rank: Contributor
timestamp: January 09, 2013, 07:49:13 pm
content: Quote from: Bored@Work on January 09, 2013, 07:47:50 pmOh I'm sorry, what I meant to say was... Is it possible to use a regular diode as a voltage reference by just forward-biasing it...

author: jeroen74
author_rank: Frequent Contributor
timestamp: January 09, 2013, 07:57:26 pm
content: The German site of Conrad has a datasheet in German and that states the 1V version is just a plain diode.http://www.produktinfo.conrad.com/datenblaetter/175000-199999/180505-da-01-de-Zenerdiode_ZPY_1_V.pdf

author: vortexnl
author_rank: Contributor
timestamp: January 09, 2013, 08:02:07 pm
content: Quote from: jeroen74 on January 09, 2013, 07:57:26 pmToo bad my german isn't that great! I guess I'll have to read the datasheet more carefully next time instead of relying on conrad's data.Many thanks to everyone that responded, my next zener purchase won't be a fail

author: Bored@Work
author_rank: Super Contributor
timestamp: January 09, 2013, 08:03:42 pm
content: Quote from: vortexnl on January 09, 2013, 07:49:13 pmSure, done all the time and there is no magic behind it. Same thing with LEDs. If the resulting regulator is "decent" depends on the requirements for that regulator.

author: PA0PBZ
author_rank: Super Contributor
timestamp: January 09, 2013, 08:21:16 pm
content: Quote from: vortexnl on January 09, 2013, 08:02:07 pmIt is the same datasheet you linked to in your first post. On the first page there is a footnote (3) behind the ZPY 1. If you look at the footnote it says: "Die ZPY 1 ist eine in Durchlassrichtung betriebene Silizium-Diode". That should not be too difficult to understand for a Dutch speaking person"("De ZPY 1 is een in doorlaatrichting gebruikte Silicium Diode")

author: jeroen74
author_rank: Frequent Contributor
timestamp: January 09, 2013, 08:29:04 pm
content: QuoteYou think? I find German quite difficult to understand while both languages probably sound very similar to people not speaking either one of them.This particular sentence wasn't too difficult though

author: vortexnl
author_rank: Contributor
timestamp: January 09, 2013, 11:19:05 pm
content: Unfortunately german isn't really my thing, I only like to learn the naughty words

author: SeanB
author_rank: Super Contributor
timestamp: January 10, 2013, 05:35:02 am
content: We probably have left the US and UK, along with the Australian readers wondering what we were discussing........

author: PA4TIM
author_rank: Super Contributor
timestamp: January 11, 2013, 06:02:15 pm
content: If you want a 1V reference you can use something like a TL431 this is a 2,5V Vref and you can use a voltage divider to get 1V. They can not deliver power. In that case you need some more electronics behind it ( like an opamp and power transistor)Also do some reading about the difference between diodes and zeners. It is in every basic electronics book.

author: UPI
author_rank: Regular Contributor
timestamp: January 11, 2013, 06:32:44 pm
content: Quote from: PA4TIM on January 11, 2013, 06:02:15 pmTL431 Calculator:http://xtronic.org/download/regulator-designer-voltage-current-shunt-adjustable/Maybe something like the attached image. You would use a divider to get it down to 1V as PA4TIM suggested.

author: Bored@Work
author_rank: Super Contributor
timestamp: January 11, 2013, 07:14:32 pm
content: The TL431 can't be easily configured for anything below it's internal 2.5 V reference.

author: PA4TIM
author_rank: Super Contributor
timestamp: January 11, 2013, 07:51:49 pm
content: Hmm, maybe if you are at one time bored at work you can read the application notes, datasheet and a book bout opamps( just kidding)I made several at 1V. But it depends wat you find easy

author: Bored@Work
author_rank: Super Contributor
timestamp: January 11, 2013, 08:30:03 pm
content: Pah. Your four references are all configured for 2.5 V and then you throw how many, 20, 30 more parts at it? All that for what started as a simple diode, and while thishttp://www.digikey.com/product-detail/en/ADR510ARTZ-REEL7/ADR510ARTZ-REEL7CT-ND/820440can be had starting at $1.75.

author: PA4TIM
author_rank: Super Contributor
timestamp: January 11, 2013, 08:50:49 pm
content: Yeah, indeed, very complex, two opamps and for a dollar worth of resistors. You are right, very heavy analog voodoo stuff. Is the modern EE afraid of everything more then one part ( most times named atmel or pic) ? They make the most simple things with an overload of digital stuff but two opamps and some resistors is heavy. I'm afraid f the future of anlog design. It takes me more time to type this than to build it.But i'm just ranting ;-)All depends on what the topic starter wants to do. If he just wants 1V and not much accuracy he can use two resistors. If he wants to make a moderate accurate Vref he can use one TL and one sinple opamp and less then 10 resistors. If he wants to make 1.000,000V he just has to forget t for nowAnd there are many more options

author: vortexnl
author_rank: Contributor
timestamp: January 12, 2013, 11:02:11 am
content: Unfortunately I live in the Netherlands and I don't have that many resources when it comes to IC's and stuff. (except ebay and stuff like that)That is why I usually like to build everything from analog parts because I don't feel like waiting 2 weeks for an IC to arrive.

author: PA4TIM
author_rank: Super Contributor
timestamp: January 12, 2013, 11:33:22 am
content: Strange, i do not have that problem and I live in the same country.Besides Conrad there are dozens of webshobs like Kent electronics,Or look here :http://www.circuitsonline.net/shops/1/name/0?type=&name=&city=&region=&country=nlBut we still do not know what you want to use a zener diode for. Where you need 1V for and how accurate should this be. Maybe there is an other way to solve this.

author: Bored@Work
author_rank: Super Contributor
timestamp: January 12, 2013, 04:00:11 pm
content: Quote from: PA4TIM on January 11, 2013, 08:50:49 pmNo, the modern EE is cost, energy, effort and space conscious and doesn't throw 30 parts on a board if a single 1.000V, three pin SOT-23-3 reference is easily available.Quote from: vortexnl on January 12, 2013, 11:02:11 amIn this threadhttp://mightyohm.com/blog/2010/11/where-do-you-shop-for-electronics/someone mentioned RS, Farnell (aka Element14) and dickbestfor the Netherlands. And someone points to a list of 120 mail-oeder shops in your neighbor country Germanyhttp://www.mikrocontroller.net/articles/Elektronikversender

author: PA4TIM
author_rank: Super Contributor
timestamp: January 12, 2013, 04:50:10 pm
content: Again, we first have to know what the TS needs.Maybe 1.0V is good enough ( because of his limmited knowlegde I do not think he want up to 1 uV precsion ;-) so probably your suggestion will be a usefull one)The ADR510 is 1.000V plus/min 3.5 mV and if he is a beginner the sot23-3 can be a problem.

author: PA4TIM
author_rank: Super Contributor
timestamp: January 17, 2013, 11:18:20 am
content: I never tried but I just read a IR led is a good 1.1V zener.

author: ConKbot
author_rank: Super Contributor
timestamp: January 17, 2013, 12:20:11 pm
content: Quote from: PA4TIM on January 12, 2013, 04:50:10 pmOh cmon nowyou can put SOT-23-3 on a 0.1" pad-per-hole perfboard. Its not the prettiest thing, but at least you dont need to buy an adaptor.

author: PA4TIM
author_rank: Super Contributor
timestamp: January 17, 2013, 12:31:47 pm
content: Hey, i solder 0603 by hand, but i have good eyes and a good solderstation. There are biginners with cheap bad solder, using S-39 and a 50W plumbers iron