On 2/9/2015 8:31 PM, David Eather wrote:> On Mon, 09 Feb 2015 11:03:05 +1000, Phil Allison <pallison49@gmail.com> > wrote: > >> 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 >> >> >> > > Do these ones look OK? I can't tell, my eyes keep going watery. (Anyone > on heart meds should not open the link!) > > http://www.ebay.com/itm/X-1-pcs-1N34A-Germanium-Diode-1st-class-post-uk- guitar-effects-pedal-use-/261498065100?pt=UK_BOI_Electrical_Components_Supplies_ET&hash=item3ce27fd0cc >Ya better hurry, only two left and he (says) he sold 78. He goes on to say you can get a shipping quote if you want to buy massive quantities. Quantity 1 - $152.58 USD, That's greedy, he should offer free shipping. :-) Mikek --- This email has been checked for viruses by Avast antivirus software. http://www.avast.com
Chinese Germanium 1N34
Started by ●February 4, 2015
Reply by ●February 11, 20152015-02-11
Reply by ●February 11, 20152015-02-11
On 2/11/2015 10:47 AM, George Herold wrote:> On Saturday, February 7, 2015 at 7:44:05 PM UTC-5, John Larkin wrote: >> On Sat, 7 Feb 2015 12:46:07 -0800 (PST), "M. Hamed" >> <mhdpublic@gmail.com> wrote: >> >>> On Friday, February 6, 2015 at 7:10:08 PM UTC-7, Phil Allison wrote: >>>> M. Hamed wrote: >>>> >>>>> So I got a bunch of these from China for a couple dollars. How can I tell they are not fakes >>>> >>>> ** Err - try visual inspection first: >>>> >>>> http://www.lessmiths.com/~kjsmith/crystal/s1N34A-3.jpg >>>> >>>> >>>> >>>> ... Phil >>> >>> 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. >> >> 1N34s could be all over the place. Point contacts are sorta random. >> >> They have a high series resistance, so the low voltage drop of >> germanium only happens at very low currents. >> >> Germanium is silly, when silicon schottky diodes are available. >> >> >> -- >> >> John Larkin Highland Technology, Inc >> picosecond timing laser drivers and controllers >> >> jlarkin att highlandtechnology dott com >> http://www.highlandtechnology.com > > OK for fun I did the I-V of a 1N34. > > https://www.dropbox.com/s/gyolf6cj5cd8erw/1N34.BMP?dl=0 > > I thought Germanium were supposed to be "more ideal" than Si diodes. > But the point contact thing looks nothing like the ideal diode model. > (log/ linear plot) > > George H. >Looks like you have some gross amount of series resistance and parallel conductance. Not too surprising in a 1N34A! Cheers Phil -- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC Optics, Electro-optics, Photonics, Analog Electronics 160 North State Road #203 Briarcliff Manor NY 10510 hobbs at electrooptical dot net http://electrooptical.net
Reply by ●February 11, 20152015-02-11
On Wed, 11 Feb 2015, George Herold wrote:> On Saturday, February 7, 2015 at 7:44:05 PM UTC-5, John Larkin wrote: >> On Sat, 7 Feb 2015 12:46:07 -0800 (PST), "M. Hamed" >> <mhdpublic@gmail.com> wrote: >> >>> On Friday, February 6, 2015 at 7:10:08 PM UTC-7, Phil Allison wrote: >>>> M. Hamed wrote: >>>> >>>>> So I got a bunch of these from China for a couple dollars. How can I tell they are not fakes >>>> >>>> ** Err - try visual inspection first: >>>> >>>> http://www.lessmiths.com/~kjsmith/crystal/s1N34A-3.jpg >>>> >>>> >>>> >>>> ... Phil >>> >>> 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. >> >> 1N34s could be all over the place. Point contacts are sorta random. >> >> They have a high series resistance, so the low voltage drop of >> germanium only happens at very low currents. >> >> Germanium is silly, when silicon schottky diodes are available. >> >> >> -- >> >> John Larkin Highland Technology, Inc >> picosecond timing laser drivers and controllers >> >> jlarkin att highlandtechnology dott com >> http://www.highlandtechnology.com > > OK for fun I did the I-V of a 1N34. > > https://www.dropbox.com/s/gyolf6cj5cd8erw/1N34.BMP?dl=0 > > I thought Germanium were supposed to be "more ideal" than Si diodes. > But the point contact thing looks nothing like the ideal diode model. > (log/ linear plot) >Nobody said they were ideal. They are "the best" in some circumstances, which probably at this point means when low forward voltage drop is desired. Michael
Reply by ●February 11, 20152015-02-11
On Wed, 11 Feb 2015 09:50:29 -0800 (PST), George Herold <gherold@teachspin.com> wrote:>On Wednesday, February 11, 2015 at 11:56:16 AM UTC-5, John Larkin wrote: >> On Wed, 11 Feb 2015 07:47:54 -0800 (PST), George Herold >> <gherold@teachspin.com> wrote: >> >> >On Saturday, February 7, 2015 at 7:44:05 PM UTC-5, John Larkin wrote: >> >> On Sat, 7 Feb 2015 12:46:07 -0800 (PST), "M. Hamed" >> >> <mhdpublic@gmail.com> wrote: >> >> >> >> >On Friday, February 6, 2015 at 7:10:08 PM UTC-7, Phil Allison wrote: >> >> >> M. Hamed wrote: >> >> >> >> >> >> > So I got a bunch of these from China for a couple dollars. How can I tell they are not fakes >> >> >> >> >> >> ** Err - try visual inspection first: >> >> >> >> >> >> http://www.lessmiths.com/~kjsmith/crystal/s1N34A-3.jpg >> >> >> >> >> >> >> >> >> >> >> >> ... Phil >> >> > >> >> >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. >> >> >> >> 1N34s could be all over the place. Point contacts are sorta random. >> >> >> >> They have a high series resistance, so the low voltage drop of >> >> germanium only happens at very low currents. >> >> >> >> Germanium is silly, when silicon schottky diodes are available. >> >> >> >> >> >> -- >> >> >> >> John Larkin Highland Technology, Inc >> >> picosecond timing laser drivers and controllers >> >> >> >> jlarkin att highlandtechnology dott com >> >> http://www.highlandtechnology.com >> > >> >OK for fun I did the I-V of a 1N34. >> > >> >https://www.dropbox.com/s/gyolf6cj5cd8erw/1N34.BMP?dl=0 >> > >> >I thought Germanium were supposed to be "more ideal" than Si diodes. >> >But the point contact thing looks nothing like the ideal diode model. >> >(log/ linear plot) >> > >> >George H. >> >> Yeah, the Ge is going ohmic past roughly 1 mA. But another 1N34 might >> be very different. >> >> Try a small-signal schottky, 1N5711 maybe. That's a high-barrier part. >> The low-barrier parts, rated a few volts reverse, are even better. > >OK 1N5711 added to plot... I think you can use the same dropbox link. >The best RF detector diodes are germanium back diodes, which are actually tunnel diodes with very low peak point currents. They are used "backwards" from the obvious polarity. -- John Larkin Highland Technology, Inc picosecond timing precision measurement jlarkin att highlandtechnology dott com http://www.highlandtechnology.com
Reply by ●February 11, 20152015-02-11
On Mon, 9 Feb 2015 17:28:43 -0800 (PST), Phil Allison <pallison49@gmail.com> wrote:> Baron wrote: > >>>> >> >> 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 look like little bullets: >> > >> > http://www.ciel-electronique.com/catalogue/Larges/JAN1N23WE.jpg >> > >> >> >> Yes those are the ones I've got. > > >** Dems are *silicon* point contact diodes. > >During WWII, we (US and Brits) were using silicon, germanium, and gallium arsenide point-contact diodes as mixers up to 30 GHz. One of the RadLab books notes that "a semiconductor triode should be possible." -- John Larkin Highland Technology, Inc picosecond timing precision measurement jlarkin att highlandtechnology dott com http://www.highlandtechnology.com
Reply by ●February 12, 20152015-02-12
On Wednesday, February 11, 2015 at 2:16:18 PM UTC-5, Phil Hobbs wrote:> On 2/11/2015 10:47 AM, George Herold wrote: > > On Saturday, February 7, 2015 at 7:44:05 PM UTC-5, John Larkin wrote: > >> On Sat, 7 Feb 2015 12:46:07 -0800 (PST), "M. Hamed" > >> <mhdpublic@gmail.com> wrote: > >> > >>> On Friday, February 6, 2015 at 7:10:08 PM UTC-7, Phil Allison wrote: > >>>> M. Hamed wrote: > >>>> > >>>>> So I got a bunch of these from China for a couple dollars. How can I tell they are not fakes > >>>> > >>>> ** Err - try visual inspection first: > >>>> > >>>> http://www.lessmiths.com/~kjsmith/crystal/s1N34A-3.jpg > >>>> > >>>> > >>>> > >>>> ... Phil > >>> > >>> 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. > >> > >> 1N34s could be all over the place. Point contacts are sorta random. > >> > >> They have a high series resistance, so the low voltage drop of > >> germanium only happens at very low currents. > >> > >> Germanium is silly, when silicon schottky diodes are available. > >> > >> > >> -- > >> > >> John Larkin Highland Technology, Inc > >> picosecond timing laser drivers and controllers > >> > >> jlarkin att highlandtechnology dott com > >> http://www.highlandtechnology.com > > > > OK for fun I did the I-V of a 1N34. > > > > https://www.dropbox.com/s/gyolf6cj5cd8erw/1N34.BMP?dl=0 > > > > I thought Germanium were supposed to be "more ideal" than Si diodes. > > But the point contact thing looks nothing like the ideal diode model. > > (log/ linear plot) > > > > George H. > > > Looks like you have some gross amount of series resistance and parallel > conductance. Not too surprising in a 1N34A!The point contact is just weird. Here's a plot of the same data but log-log. https://www.dropbox.com/s/5irzzrpshuqgqfk/1N34-B.BMP?dl=0 My eye wanted to put put two lines through the data, so lines were added by eye. Two power laws? George H.> > Cheers > > Phil > > -- > Dr Philip C D Hobbs > Principal Consultant > ElectroOptical Innovations LLC > Optics, Electro-optics, Photonics, Analog Electronics > > 160 North State Road #203 > Briarcliff Manor NY 10510 > > hobbs at electrooptical dot net > http://electrooptical.net
Reply by ●February 13, 20152015-02-13
So first, here is what mine look like: http://cfnewsads.thomasnet.com/images/cmsimage/image/automation-electronics/zener-diode-sample.JPG except that they don't seem to have any visible marking
Reply by ●February 13, 20152015-02-13
Second, I wanted to create a diode curve tracer to test these new diodes using scope X-Y mode. Problem of course that my ramp generator is grounded so I can't probe at two different point pairs. It's funny how I had all these complicated ideas to solve this problem including using a difference amplifier to convert the voltage difference across the diode to a voltage referenced to ground. Then I decided to google search, and after 5 mins, it's funny how the solution was way simpler. Plug the function generator into a 3-2 prong adapter. DUH!
Reply by ●February 13, 20152015-02-13
On Thursday, February 12, 2015 at 12:11:21 PM UTC-8, George Herold wrote:> > > OK for fun I did the I-V of a 1N34. >> > > > > > https://www.dropbox.com/s/gyolf6cj5cd8erw/1N34.BMP?dl=0 > > > > > > I thought Germanium were supposed to be "more ideal" than Si diodes. > > > But the point contact thing looks nothing like the ideal diode model. > > > (log/ linear plot)> The point contact is just weird. Here's a plot of the same data > but log-log. > > https://www.dropbox.com/s/5irzzrpshuqgqfk/1N34-B.BMP?dl=0That's normal. The so-called 'ideal diode equation' is Shockley's model for a planar diode (i.e. the depletion region is constant area, variable thickness), but a point=contact diode has a depletion region which is a hemisphere around the point of contact (area proportional to R squared). The Ge point contact diodes worked well, because the low bandgap made impurities relatively benign (and that contact point has to be at the semiconductor surface, which is always dirty). Capacitance was low, and gigahertz operation was easy. Silicon point contact isn't as reliable because there's more dirt sensitivity, and the higher forward voltage means a surface electric field (attracts more dirt). Shottky diodes for RF are not point-contact types. Are ANY point-contact diodes still in production?
Reply by ●February 13, 20152015-02-13
Finally, with my scope diode curve tracer, I got some data.=20 1- A schottky diode (1N5189) -> turns on around .2V and then current goes u= p really fast 2- A Germanium diode with clear glass and a green stripe -> turns on around= .2V but current rises REALLY slowly with voltage. I knew this already. Ger= manium diodes have less steep curve and that's why they have some applicati= on in audio. 3- My presumed 1N34 -> turns on around .2V but current rise slower than (1)= and faster than (2). So at this point I wasn't sure, so I dug around for more "clear glass" germ= aniums I had. I found one that looks almost identical to diode #2 but with = a black stripe rather than a green one. I put it in my test circuit, and th= e result is almost identical to #3. So I can't tell if my diode is 1N34 or not, but I'm positive it could be a = Germanium diode since it acts like another Germanium diode. Time to give the seller positive feedback!
