On Sat, 14 Feb 2015 11:49:36 +1000, Michael Black <et472@ncf.ca> wrote:> On Fri, 13 Feb 2015, M. Hamed wrote: > >> On Thursday, February 12, 2015 at 11:19:36 PM UTC-7, Phil Allison wrote: >>> >>> ** Well, they are cleary zener diodes - like the link says. >>> >> >> Have you ever seen low forward voltage zener diodes? That would be new >> to me. The forward drop on these are about .2V-.3V >> > A zener by definition is reverse biased.Not so, and by the way all diodes are zener diodes - we just don't normally run them in the breakdown region.
Chinese Germanium 1N34
Started by ●February 4, 2015
Reply by ●February 14, 20152015-02-14
Reply by ●February 14, 20152015-02-14
M. Hamed wrote: Phil Allison wrote:> > > > ** But the pic IS of some Philips zeners - it damn we says so. > > > > That's why I said "Looks like" not "exactly absolutely identical"** FFS - READ the rest of my post you snipped to pieces. You steaming fuckwit.
Reply by ●February 15, 20152015-02-15
On Sun, 15 Feb 2015, David Eather wrote:> On Sat, 14 Feb 2015 11:49:36 +1000, Michael Black <et472@ncf.ca> wrote: > >> On Fri, 13 Feb 2015, M. Hamed wrote: >> >>> On Thursday, February 12, 2015 at 11:19:36 PM UTC-7, Phil Allison wrote: >>>> >>>> ** Well, they are cleary zener diodes - like the link says. >>>> >>> >>> Have you ever seen low forward voltage zener diodes? That would be new to >>> me. The forward drop on these are about .2V-.3V >>> >> A zener by definition is reverse biased. > > Not so, and by the way all diodes are zener diodes - we just don't normally > run them in the breakdown region.Yes, all diodes can "zener" but they are reversed biased. One surplus store here used to sell "zeners", some specific voltage, and they were plastic encased transistors with a lead cut off. They must have gotten them that way. Michael
Reply by ●February 15, 20152015-02-15
On Sat, 14 Feb 2015, jurb6006@gmail.com wrote:>> "During WWII, we (US and Brits) were using silicon, germanium, and >> gallium arsenide point-contact diodes as mixers up to 30 GHz." > > Huh ? >Explain which part and you'll get some deeper answer. Michael
Reply by ●February 15, 20152015-02-15
On Mon, 9 Feb 2015 15:11:47 -0500, Michael Black <et472@ncf.ca> wrote:>On Mon, 9 Feb 2015, Baron wrote: > >> Phil Allison prodded the keyboard >> >>> Baron wrote: >>> >>>>>> >>>>>> ** Err - try visual inspection first: >>>>>> >>>>>> http://www.lessmiths.com/~kjsmith/crystal/s1N34A-3.jpg >>>>>> >>> >>>>> >>>>> They look nothing like that. But if 1N34 is a pretty generic >>>>> diode, there could be more than one manufacturer I assume. >>>>> >>>>> The drop is about .2-.3V but the first datasheet I looked up, >>>>> doesn't match the parameters I'm getting. >>>> >>>> No it doesn't look like any of my 1N34's either ! >>> >>> >>> ** Wot - not clear glass and no die on the end of a header or tiny >>> wire making a point contact? >>> >>> Sure your 1N34s are genuine ? >>> >>> >>> >>> >>> .... Phil >> >> Oops, Sorry Phil, Guys. A brain fart ! >> I've just looked at the ones I have, they are 1N23. Still in the lead >> foil packets. >> >SO they are microwave diodes. Apparently they don't want much current >through them, one was not supposed to use a VOM to check them (so I'm not >sure if a DMM is acceptable or not). > >That's the progression. In WWII, they worked on radar, improving it and >finding that they needed to move up in frequency in order to get good >enough definition. In doing so, they helped pave the way for more use of >those higher frequencies after the war. They were able to get tubes to >transmit up there (by making new types of tubes) but had problems with >tubes that operated up there. So they went to crystal diode mixers, and >went back to the "cat's whisker" of the early days, except making it more >stable, so you didn't have to fiddle to find where on the surface there >was good operation.The USians kept trying to use tubes as mixers, and they didn't work well at GHz. The Brits pushed point-contact diodes, which worked. The trick was then to keep the megawatt transmit magnetrons (another Brit contribution) from blowing out the delicate receive mixer diodes. By the end of the war, we were building radars that had ranges about 2:1 worse than the theoretical limits. https://dl.dropboxusercontent.com/u/53724080/Oldies/MoonBounce.JPG And that caused the 1N34 to come along after the war,>and it caused Bell to look at the transistor after the war. I forget the >title, but there is a book about this, something about the invention that >changed the war, which is interesting in telling the story of Radar >development during WWII, and its impact after the war.Good book: http://www.amazon.com/Invention-That-Changed-World-Technological/dp/0684810212/ref=sr_1_1?ie=UTF8&qid=1424027721&sr=8-1&keywords=buderi+invention The prime material is the MIT RadLab series, published just after the war, to document the technology. Volume 15 is "Crystal Rectifiers" http://www.mit.edu/~klund/books/radlab.html Good stuff, the birth of modern electronics.> >I noticed something interesting related to the 1N34 a few years ago. I >had downloaded a 1930s copy of The Radio Handbook and one of the people >thanked at the beginning was Rufus P. Turner.Interesting reference, Turner. I hadn't heard of him before.
Reply by ●February 15, 20152015-02-15
On Sun, 15 Feb 2015 13:36:51 -0500, Michael Black <et472@ncf.ca> wrote:>On Sun, 15 Feb 2015, David Eather wrote: > >> On Sat, 14 Feb 2015 11:49:36 +1000, Michael Black <et472@ncf.ca> wrote: >> >>> On Fri, 13 Feb 2015, M. Hamed wrote: >>> >>>> On Thursday, February 12, 2015 at 11:19:36 PM UTC-7, Phil Allison wrote: >>>>> >>>>> ** Well, they are cleary zener diodes - like the link says. >>>>> >>>> >>>> Have you ever seen low forward voltage zener diodes? That would be new to >>>> me. The forward drop on these are about .2V-.3V >>>> >>> A zener by definition is reverse biased. >> >> Not so, and by the way all diodes are zener diodes - we just don't normally >> run them in the breakdown region. > >Yes, all diodes can "zener" but they are reversed biased. > >One surplus store here used to sell "zeners", some specific voltage, and >they were plastic encased transistors with a lead cut off. They must have >gotten them that way. > > MichaelThe b-e junction of a transistor often makes a good zener, roughly 5 volts typically. There are some transistors that you can use emitter to collactor as a reference zener, which is a zener with a forward diode in series, with a net tempco near zero. That's a lot cheaper than buying a classic 2-chip reference zener. 6.2 volts seems to be the magic number. Of course, IC references are better now.
Reply by ●February 15, 20152015-02-15
On Mon, 16 Feb 2015 04:36:51 +1000, Michael Black <et472@ncf.ca> wrote:> On Sun, 15 Feb 2015, David Eather wrote: > >> On Sat, 14 Feb 2015 11:49:36 +1000, Michael Black <et472@ncf.ca> wrote: >> >>> On Fri, 13 Feb 2015, M. Hamed wrote: >>> >>>> On Thursday, February 12, 2015 at 11:19:36 PM UTC-7, Phil Allison >>>> wrote: >>>>> ** Well, they are cleary zener diodes - like the link says. >>>>> >>>> Have you ever seen low forward voltage zener diodes? That would be >>>> new to me. The forward drop on these are about .2V-.3V >>>> >>> A zener by definition is reverse biased. >> >> Not so, and by the way all diodes are zener diodes - we just don't >> normally run them in the breakdown region. > > Yes, all diodes can "zener" but they are reversed biased.So what? All standard zener diodes are used in reversed bias mode too. Go back to basics.
Reply by ●February 15, 20152015-02-15
On Sunday, February 15, 2015 at 1:10:21 PM UTC-7, David Eather wrote:> So what? All standard zener diodes are used in reversed bias mode too. Go > back to basics.I thought someone here or elsewhere mentioned that Zener effect is not necessarily the same as the avalanche effect in regular diodes.
Reply by ●February 15, 20152015-02-15
On Sunday, February 15, 2015 at 12:31:12 PM UTC-7, John Larkin wrote:> The b-e junction of a transistor often makes a good zener, roughly 5 > volts typically. > > There are some transistors that you can use emitter to collactor as a > reference zener, which is a zener with a forward diode in series, with > a net tempco near zero. That's a lot cheaper than buying a classic > 2-chip reference zener. 6.2 volts seems to be the magic number. >I'm gonna have to try that! just for kicks
Reply by ●February 15, 20152015-02-15
On Sun, 15 Feb 2015 12:39:52 -0800 (PST), "M. Hamed" <mhdpublic@gmail.com> wrote:>On Sunday, February 15, 2015 at 1:10:21 PM UTC-7, David Eather wrote: >> So what? All standard zener diodes are used in reversed bias mode too. Go >> back to basics. > >I thought someone here or elsewhere mentioned that Zener effect is not necessarily the same as the avalanche effect in regular diodes.The physics is different, zener (quantum tunnelling) at low voltages and avalanche at high voltages, midway being around 5 volts maybe. Most people and data sheets call all such diodes "zeners."
