Tim Williams wrote:> "Joerg" <invalid@invalid.invalid> wrote in message > news:b86fc3Fcvs7U1@mid.individual.net... >> Imagine, a diode in a large glass cylinder that is painted shiny black. >> Today's kids don't even recognize those as semiconductors. > > Today's kids don't know the word "semiconductor" :-( >That's why you have to bring it to them in a different way, like Cypress in this example :-) http://www.flickr.com/photos/prxinc/4194214608/ -- Regards, Joerg http://www.analogconsultants.com/
1N34A Germanium Diode finally found!!
Started by ●August 27, 2013
Reply by ●August 28, 20132013-08-28
Reply by ●August 28, 20132013-08-28
On 8/28/2013 11:13 AM, John Larkin wrote:> On Wed, 28 Aug 2013 07:21:40 -0700, Joerg <invalid@invalid.invalid> wrote: > >> Tim Williams wrote: >>> "John Larkin" <jjlarkin@highNOTlandTHIStechnologyPART.com> wrote in >>> message news:k2tq19hm62ir3fttudo16p2vu4meefdnk1@4ax.com... >>>> On Tue, 27 Aug 2013 19:27:37 -0700 (PDT), cgage.com@gmail.com wrote: >>>> >>>>> I finally found some 1n34a diodes and one of my new favorite sites! >>>>> >>>>> http://www.bgmicro.com/1n34a-germanium-diode.aspx >>>> What do you want it for? A low-barrier schottky is probably better for >>>> most >>>> uses. >>> >>> Hmm, Vf and leakage are about the same, aren't they... >> >> >> The same? Half a year ago I had a case where I needed to quickly decode >> a weak RF signal, having only an oscilloscope available. Several small >> signal Schottky diodes only produced fuzz. Luckily I had hoarded >> scavenged Ge-Diodes as a kid and mostly carry some to sites. An OA85 >> wasn't a ton better but still so much that I was able to decipher the >> signal. >> >> Imagine, a diode in a large glass cylinder that is painted shiny black. >> Today's kids don't even recognize those as semiconductors. > > Any idea why the ge diode worked better? > > The 1N34 data sheets are very sparse. None that I've seen have v-i curves, and > they spec current of a few mA at ONE VOLT forward. > > Being a point contact device, capacitance is low and series resistance is high. > > I like the Skyworks SMS7621. 0.25 pF, around 300 mV at 1 mA, and way less series > resistance than a 1N34. > >John, Ben Tongue of Blonder-Tongue fame has written about this... why this diode over that in crystal radios. Different signal levels require a different diode to be optimum. (level and impedance) Here's one article about diodes in crystal radios. http://www.bentongue.com/xtalset/4opd_xfr/4opd_xfr.html There are more articles. This comes from Ben's extensive research about crystal radios, here. http://www.bentongue.com/xtalset/xtalset.html Contains 30 articles on crystal radio design and optimization. And some of his early life experiences found here. http://www.bentongue.com/ You will probably find it interesting. Mikek
Reply by ●August 28, 20132013-08-28
John Larkin wrote:> On Wed, 28 Aug 2013 07:21:40 -0700, Joerg <invalid@invalid.invalid> wrote: > >> Tim Williams wrote: >>> "John Larkin" <jjlarkin@highNOTlandTHIStechnologyPART.com> wrote in >>> message news:k2tq19hm62ir3fttudo16p2vu4meefdnk1@4ax.com... >>>> On Tue, 27 Aug 2013 19:27:37 -0700 (PDT), cgage.com@gmail.com wrote: >>>> >>>>> I finally found some 1n34a diodes and one of my new favorite sites! >>>>> >>>>> http://www.bgmicro.com/1n34a-germanium-diode.aspx >>>> What do you want it for? A low-barrier schottky is probably better for >>>> most >>>> uses. >>> Hmm, Vf and leakage are about the same, aren't they... >> >> The same? Half a year ago I had a case where I needed to quickly decode >> a weak RF signal, having only an oscilloscope available. Several small >> signal Schottky diodes only produced fuzz. Luckily I had hoarded >> scavenged Ge-Diodes as a kid and mostly carry some to sites. An OA85 >> wasn't a ton better but still so much that I was able to decipher the >> signal. >> >> Imagine, a diode in a large glass cylinder that is painted shiny black. >> Today's kids don't even recognize those as semiconductors. > > Any idea why the ge diode worked better? >Probably because of the lower Vf. Also, it has a really low capacitance, usuall less than 1pF at -1V.> The 1N34 data sheets are very sparse. None that I've seen have v-i curves, and > they spec current of a few mA at ONE VOLT forward. >For the OA85 the curve starts going like a rocket at 200mV: http://www.datasheet4u.net/download.php?id=614685 A Schottky can't do that. Unfortunately they discontinued it already in the 60's when I was a kid. But I scavenged lots from discardrd TV sets. They used them everywhere, not just for demodulating. I also got some of the smaller ones that replaced it.> Being a point contact device, capacitance is low and series resistance is high. >And they really do not like heat. Any heat.> I like the Skyworks SMS7621. 0.25 pF, around 300 mV at 1 mA, and way less series > resistance than a 1N34. >That's a nice diode. But probably quite pricey. Can it do 200mV at 100uA like the OA85? -- Regards, Joerg http://www.analogconsultants.com/
Reply by ●August 28, 20132013-08-28
On Wed, 28 Aug 2013 09:13:54 -0700, John Larkin wrote:> On Wed, 28 Aug 2013 07:21:40 -0700, Joerg <invalid@invalid.invalid> > wrote: > >>Tim Williams wrote: >>> "John Larkin" <jjlarkin@highNOTlandTHIStechnologyPART.com> wrote in >>> message news:k2tq19hm62ir3fttudo16p2vu4meefdnk1@4ax.com... >>>> On Tue, 27 Aug 2013 19:27:37 -0700 (PDT), cgage.com@gmail.com wrote: >>>> >>>>> I finally found some 1n34a diodes and one of my new favorite sites! >>>>> >>>>> http://www.bgmicro.com/1n34a-germanium-diode.aspx >>>> What do you want it for? A low-barrier schottky is probably better >>>> for most >>>> uses. >>> >>> Hmm, Vf and leakage are about the same, aren't they... >> >> >>The same? Half a year ago I had a case where I needed to quickly decode >>a weak RF signal, having only an oscilloscope available. Several small >>signal Schottky diodes only produced fuzz. Luckily I had hoarded >>scavenged Ge-Diodes as a kid and mostly carry some to sites. An OA85 >>wasn't a ton better but still so much that I was able to decipher the >>signal. >> >>Imagine, a diode in a large glass cylinder that is painted shiny black. >>Today's kids don't even recognize those as semiconductors. > > Any idea why the ge diode worked better? > > The 1N34 data sheets are very sparse. None that I've seen have v-i > curves, and they spec current of a few mA at ONE VOLT forward. > > Being a point contact device, capacitance is low and series resistance > is high. > > I like the Skyworks SMS7621. 0.25 pF, around 300 mV at 1 mA, and way > less series resistance than a 1N34.The (Ge) 1N270 has a bit lower forward voltage (~0.265V @1mA for at least a few samples I have laying around). Data sheet is similarly sparse. They seem to be still available, perhaps old stock.
Reply by ●August 28, 20132013-08-28
On Wed, 28 Aug 2013 17:23:30 +0000 (UTC), Frank Miles <fpm@u.washington.edu> wrote:>On Wed, 28 Aug 2013 09:13:54 -0700, John Larkin wrote: > >> On Wed, 28 Aug 2013 07:21:40 -0700, Joerg <invalid@invalid.invalid> >> wrote: >> >>>Tim Williams wrote: >>>> "John Larkin" <jjlarkin@highNOTlandTHIStechnologyPART.com> wrote in >>>> message news:k2tq19hm62ir3fttudo16p2vu4meefdnk1@4ax.com... >>>>> On Tue, 27 Aug 2013 19:27:37 -0700 (PDT), cgage.com@gmail.com wrote: >>>>> >>>>>> I finally found some 1n34a diodes and one of my new favorite sites! >>>>>> >>>>>> http://www.bgmicro.com/1n34a-germanium-diode.aspx >>>>> What do you want it for? A low-barrier schottky is probably better >>>>> for most >>>>> uses. >>>> >>>> Hmm, Vf and leakage are about the same, aren't they... >>> >>> >>>The same? Half a year ago I had a case where I needed to quickly decode >>>a weak RF signal, having only an oscilloscope available. Several small >>>signal Schottky diodes only produced fuzz. Luckily I had hoarded >>>scavenged Ge-Diodes as a kid and mostly carry some to sites. An OA85 >>>wasn't a ton better but still so much that I was able to decipher the >>>signal. >>> >>>Imagine, a diode in a large glass cylinder that is painted shiny black. >>>Today's kids don't even recognize those as semiconductors. >> >> Any idea why the ge diode worked better? >> >> The 1N34 data sheets are very sparse. None that I've seen have v-i >> curves, and they spec current of a few mA at ONE VOLT forward. >> >> Being a point contact device, capacitance is low and series resistance >> is high. >> >> I like the Skyworks SMS7621. 0.25 pF, around 300 mV at 1 mA, and way >> less series resistance than a 1N34. > >The (Ge) 1N270 has a bit lower forward voltage (~0.265V @1mA for at least a few samples >I have laying around). Data sheet is similarly sparse. They seem to be still >available, perhaps old stock.In the mid to late '80's I used 1N270's by the bucket load to clamp LM324 and LM329 inputs, to avoid substrate diode injection and phase inversion. ...Jim Thompson -- | James E.Thompson | mens | | Analog Innovations | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | San Tan Valley, AZ 85142 Skype: Contacts Only | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at http://www.analog-innovations.com | 1962 | I love to cook with wine. Sometimes I even put it in the food.
Reply by ●August 28, 20132013-08-28
On Wed, 28 Aug 2013 10:17:08 -0700, Joerg <invalid@invalid.invalid> wrote:>John Larkin wrote: >> On Wed, 28 Aug 2013 07:21:40 -0700, Joerg <invalid@invalid.invalid> wrote: >> >>> Tim Williams wrote: >>>> "John Larkin" <jjlarkin@highNOTlandTHIStechnologyPART.com> wrote in >>>> message news:k2tq19hm62ir3fttudo16p2vu4meefdnk1@4ax.com... >>>>> On Tue, 27 Aug 2013 19:27:37 -0700 (PDT), cgage.com@gmail.com wrote: >>>>> >>>>>> I finally found some 1n34a diodes and one of my new favorite sites! >>>>>> >>>>>> http://www.bgmicro.com/1n34a-germanium-diode.aspx >>>>> What do you want it for? A low-barrier schottky is probably better for >>>>> most >>>>> uses. >>>> Hmm, Vf and leakage are about the same, aren't they... >>> >>> The same? Half a year ago I had a case where I needed to quickly decode >>> a weak RF signal, having only an oscilloscope available. Several small >>> signal Schottky diodes only produced fuzz. Luckily I had hoarded >>> scavenged Ge-Diodes as a kid and mostly carry some to sites. An OA85 >>> wasn't a ton better but still so much that I was able to decipher the >>> signal. >>> >>> Imagine, a diode in a large glass cylinder that is painted shiny black. >>> Today's kids don't even recognize those as semiconductors. >> >> Any idea why the ge diode worked better? >> > >Probably because of the lower Vf. Also, it has a really low capacitance, >usuall less than 1pF at -1V. > > >> The 1N34 data sheets are very sparse. None that I've seen have v-i curves, and >> they spec current of a few mA at ONE VOLT forward. >> > >For the OA85 the curve starts going like a rocket at 200mV: > >http://www.datasheet4u.net/download.php?id=614685 > >A Schottky can't do that. Unfortunately they discontinued it already in >the 60's when I was a kid. But I scavenged lots from discardrd TV sets. >They used them everywhere, not just for demodulating. I also got some of >the smaller ones that replaced it. > > >> Being a point contact device, capacitance is low and series resistance is high. >> > >And they really do not like heat. Any heat. > > >> I like the Skyworks SMS7621. 0.25 pF, around 300 mV at 1 mA, and way less series >> resistance than a 1N34. >> > >That's a nice diode. But probably quite pricey. Can it do 200mV at 100uA >like the OA85?It's about 195 mv at 100 ua. Series resistance is a lot less. 1N34 is a resistor above about 1 mA. Want some? We pay about 35 cents for the 7621. Skyworks has an even lower-barrier part, SMS1546, but it's half a pF. -- John Larkin Highland Technology, Inc jlarkin at highlandtechnology dot com http://www.highlandtechnology.com Precision electronic instrumentation Picosecond-resolution Digital Delay and Pulse generators Custom laser drivers and controllers Photonics and fiberoptic TTL data links VME thermocouple, LVDT, synchro acquisition and simulation
Reply by ●August 28, 20132013-08-28
John Larkin wrote:> On Wed, 28 Aug 2013 10:17:08 -0700, Joerg <invalid@invalid.invalid> > wrote: > >> John Larkin wrote: >>> On Wed, 28 Aug 2013 07:21:40 -0700, Joerg <invalid@invalid.invalid> wrote: >>> >>>> Tim Williams wrote: >>>>> "John Larkin" <jjlarkin@highNOTlandTHIStechnologyPART.com> wrote in >>>>> message news:k2tq19hm62ir3fttudo16p2vu4meefdnk1@4ax.com... >>>>>> On Tue, 27 Aug 2013 19:27:37 -0700 (PDT), cgage.com@gmail.com wrote: >>>>>> >>>>>>> I finally found some 1n34a diodes and one of my new favorite sites! >>>>>>> >>>>>>> http://www.bgmicro.com/1n34a-germanium-diode.aspx >>>>>> What do you want it for? A low-barrier schottky is probably better for >>>>>> most >>>>>> uses. >>>>> Hmm, Vf and leakage are about the same, aren't they... >>>> The same? Half a year ago I had a case where I needed to quickly decode >>>> a weak RF signal, having only an oscilloscope available. Several small >>>> signal Schottky diodes only produced fuzz. Luckily I had hoarded >>>> scavenged Ge-Diodes as a kid and mostly carry some to sites. An OA85 >>>> wasn't a ton better but still so much that I was able to decipher the >>>> signal. >>>> >>>> Imagine, a diode in a large glass cylinder that is painted shiny black. >>>> Today's kids don't even recognize those as semiconductors. >>> Any idea why the ge diode worked better? >>> >> Probably because of the lower Vf. Also, it has a really low capacitance, >> usuall less than 1pF at -1V. >> >> >>> The 1N34 data sheets are very sparse. None that I've seen have v-i curves, and >>> they spec current of a few mA at ONE VOLT forward. >>> >> For the OA85 the curve starts going like a rocket at 200mV: >> >> http://www.datasheet4u.net/download.php?id=614685 >> >> A Schottky can't do that. Unfortunately they discontinued it already in >> the 60's when I was a kid. But I scavenged lots from discardrd TV sets. >> They used them everywhere, not just for demodulating. I also got some of >> the smaller ones that replaced it. >> >> >>> Being a point contact device, capacitance is low and series resistance is high. >>> >> And they really do not like heat. Any heat. >> >> >>> I like the Skyworks SMS7621. 0.25 pF, around 300 mV at 1 mA, and way less series >>> resistance than a 1N34. >>> >> That's a nice diode. But probably quite pricey. Can it do 200mV at 100uA >> like the OA85? > > It's about 195 mv at 100 ua. Series resistance is a lot less. 1N34 is > a resistor above about 1 mA. Want some? >Nah, thanks. I've got a lot of Ge-Diodes here to last me for the rest of my life, and then some. The series resistance doesn't matter much in RF detectors, usually.> We pay about 35 cents for the 7621. Skyworks has an even lower-barrier > part, SMS1546, but it's half a pF. >35c is very tolerable, that's less than 10% of an Anchor Steam OBA. -- Regards, Joerg http://www.analogconsultants.com/
Reply by ●August 28, 20132013-08-28
Greegor Inscribed thus:> 1N34A is a classic for crystal radio sets.So is OA79/80/81 -- Best Regards: Baron.
Reply by ●August 28, 20132013-08-28
On Wed, 28 Aug 2013 21:54:09 +0100, Baron wrote:> Greegor Inscribed thus: > >> 1N34A is a classic for crystal radio sets. > > So is OA79/80/81Point contact diodes are cheating;-) A *real* crystal radio uses a piece of carborundum and a razor blade... -- "Design is the reverse of analysis" (R.D. Middlebrook)
Reply by ●August 28, 20132013-08-28
Fred Abse Inscribed thus:> On Wed, 28 Aug 2013 21:54:09 +0100, Baron wrote: > >> Greegor Inscribed thus: >> >>> 1N34A is a classic for crystal radio sets. >> >> So is OA79/80/81 > > Point contact diodes are cheating;-) > > A *real* crystal radio uses a piece of carborundum and a razor > blade... >I recall using a piece of coal and a small spring with the end turn snapped off ! -- Best Regards: Baron.
