On 08/28/13 17:53, Jim Thompson wrote:> > 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 ThompsonAnyone remember the GE "back" diodes ?. Same can as their tunnel diodes, but, iirc, very low forward voltage... Chris
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 Wed, 28 Aug 2013 22:55:24 +0000, chris <meru@devnull.com> wrote:>On 08/28/13 17:53, Jim Thompson wrote: > >> >> 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 > >Anyone remember the GE "back" diodes ?. Same can as their tunnel diodes, >but, iirc, very low forward voltage... > >ChrisPeople still make Ge back diodes, as rf detectors. They are, I think, the only planar "ic" type fabrication done in germanium, except photodiodes maybe. http://www.aeroflex.com/AMS/Metelics/pdfiles/MBD_Series_Planar_Back_Tunnel_Diodes.pdf They conduct better in the reverse direction than forward, hence the name. -- 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
On 8/27/2013 7:27 PM, 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.aspxI would have suggested Polypaks.
Reply by ●August 28, 20132013-08-28
On 8/28/2013 8:18 PM, sms wrote:> On 8/27/2013 7:27 PM, 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 > > I would have suggested Polypaks. >Now _there's_ a blast from the past. I remember when Digikey was Poly Paks' main competitor, and Jameco was the gold standard. ;) Cheers Phil Hobbs -- 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 USA +1 845 480 2058 hobbs at electrooptical dot net http://electrooptical.net
Reply by ●August 28, 20132013-08-28
On 8/28/2013 7:37 PM, John Larkin wrote:> On Wed, 28 Aug 2013 22:55:24 +0000, chris <meru@devnull.com> wrote: > >> On 08/28/13 17:53, Jim Thompson wrote: >> >>> >>> 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 >> >> Anyone remember the GE "back" diodes ?. Same can as their tunnel diodes, >> but, iirc, very low forward voltage... >> >> Chris > > People still make Ge back diodes, as rf detectors. They are, I think, > the only planar "ic" type fabrication done in germanium, except > photodiodes maybe. > > http://www.aeroflex.com/AMS/Metelics/pdfiles/MBD_Series_Planar_Back_Tunnel_Diodes.pdf > > They conduct better in the reverse direction than forward, hence the > name.Making an AM detector that has both good linearity and a reasonable dynamic range is one of those deceptively hard problems. I tend to do one of two things: one or more DLVAs (e.g. SA614s) with some auxiliary calibrator, such as a crystal ringing down, or a PLL with fairly careful offset nulling. Ring-down calibration is convenient, because your average 80 MHz crystal rings down at something like 1 dB/ms or a bit less. You can anchor the high-amplitude end with linear measurements, and rely on the exponential falloff for the lower-amplitude range. Cheers Phil Hobbs -- 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 USA +1 845 480 2058 hobbs at electrooptical dot net http://electrooptical.net
Reply by ●August 28, 20132013-08-28
On Wed, 28 Aug 2013 20:36:20 -0400, Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:>On 8/28/2013 7:37 PM, John Larkin wrote: >> On Wed, 28 Aug 2013 22:55:24 +0000, chris <meru@devnull.com> wrote: >> >>> On 08/28/13 17:53, Jim Thompson wrote: >>> >>>> >>>> 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 >>> >>> Anyone remember the GE "back" diodes ?. Same can as their tunnel diodes, >>> but, iirc, very low forward voltage... >>> >>> Chris >> >> People still make Ge back diodes, as rf detectors. They are, I think, >> the only planar "ic" type fabrication done in germanium, except >> photodiodes maybe. >> >> http://www.aeroflex.com/AMS/Metelics/pdfiles/MBD_Series_Planar_Back_Tunnel_Diodes.pdf >> >> They conduct better in the reverse direction than forward, hence the >> name. > >Making an AM detector that has both good linearity and a reasonable >dynamic range is one of those deceptively hard problems. > >I tend to do one of two things: one or more DLVAs (e.g. SA614s) with >some auxiliary calibrator, such as a crystal ringing down, or a PLL with >fairly careful offset nulling. > >Ring-down calibration is convenient, because your average 80 MHz crystal >rings down at something like 1 dB/ms or a bit less. You can anchor the >high-amplitude end with linear measurements, and rely on the exponential >falloff for the lower-amplitude range. > >Cheers > >Phil HobbsDoes anyone actually use just a diode for AM detection anymore? ...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 29, 20132013-08-29
On 8/28/2013 5:23 PM, Phil Hobbs wrote:> On 8/28/2013 8:18 PM, sms wrote: >> On 8/27/2013 7:27 PM, 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 >> >> I would have suggested Polypaks. >> > > Now _there's_ a blast from the past. I remember when Digikey was Poly > Paks' main competitor, and Jameco was the gold standard. ;)I recall Jameco, well "James Electronics" as Digikey's competitor. Been using both of them for at least 35 years. My first job out of college was right across the street from James Electronics in San Carlos. Now I do will call if I need something fast. There were some other surplus companies that were Polypak's competition. A company in Florida called Knapp Electronics that printed their catalog on newsprint.
Reply by ●August 29, 20132013-08-29
> I remember when Digikey was Poly Paks' > main competitor, and Jameco was =the > gold standard. ;)=20 =20 Electronics surplus was a blast back then. There was a Cortland Electronics= that advertized in the ad section at the back of many electronic hobby mag= azines and had a short catalog of oddball stuff? I remember they got surplu= s stock of big old Burroughs Nixie tubes and circuit cards full of huge nak= ed reed switches (originally intended for telephone switching?) Each reed w= as like 2 1/2 inches long and the sound they made when closed or opened was= almost like a musical tuning fork. =20 My Dad taught me how to do high quality soldering when I was 9 or so. I rem= ember mounting an old tube TV power transformer in a box to power an elemen= tary school science fair project where I recreated Edison's light bulb expe= riments by winding various types of iron wire around a large sewing needle = to make tiny coils and knowing that vacuum and gas apparatus were out of re= ach for me at the time. The large amperage 6.3V tube filament power would m= ake the filaments glow and then flare and burn open quite nicely. The highe= r voltage taps were stubbed and insulated for safety. It was a nice science= fair project actually, kids liked seeing the filaments glow briefly and th= en burn open. Good for elementary school. =20 At 12 I was building simple audio oscillators that used two multivibrator c= ircuits so they warbled. My favorite used 2 PNP and 2 NPN and by changing t= he various timing values the noise could be varied wildly. My Dad wanted a = loud noisemaker for the business garage so I hung a power transistor and a = big scavanged speaker at the end and the warble would cut through a lot of = engine noise. I think I built that when I was like 13 and that loud thing k= ept running for a decade at least. After a few years it surprised somebody = a bit too much so he put a pot or resistor in series with the speaker to dr= op the volume and it kept running for many years. =20 By the time I was 18 I was building projects and buying parts from James El= ectronics (later Jameco) and Mouser. When I got into TTL I actually missed = drawing traces and pads by hand using Sharpie markers as etch resist and et= ching with a bottle of Radio Shack Ferric Chloride. I could do a one off pr= etty fast. I'd go over the traces a second time with sharpie intil the shar= pie ink was fairly dark to guarantee good resist. When I was in college, a = few times I would wake up in the middle of the night with a TTL circuit ide= a I just had to commit to paper right away. At least two of them were TTL a= nd did get built. =20 The local electronics surplus retailers in Minneapolis had quite a heyday i= n the late 1970's as well. Some hobbyist printed up and handed out a map to= the best dozen or so at one point. There was lots of really good mil grade= stuff surplused off cheap. =20 A few years later a quantity of Teddy Ruxpin motorized eyeballs ended up in= the Minneapolis surplus market. They seemed oddly out of place to me, more= like the kind of surplus you'd expect in the Santa Clara Valley in Califor= nia. Shifty wiggling eyeballs appeared in a few bizarre places for awhile a= fter that. They hinted at robotics back then but if you look at the old Ted= dy Ruxpin ads on Youtube compare them with Furby of today, Teddy Ruxpin loo= ks really sad with a cassette tape shoved in his backside.=20 =20 http://www.youtube.com/watch?v=3D8EshrR-xk2E =20 =20 Obscene but thorough explanation of Teddy Ruxpin =20 http://www.youtube.com/watch?v=3DzK1a_WKY7Po
Reply by ●August 29, 20132013-08-29
On 28.8.13 11:58 , Fred Abse wrote:> 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... >The classical one was a piece of galenite (lead sulfide PbS) and a catwhisker, to create the first Schottky diode. -- -Tauno Voipio
Reply by ●August 29, 20132013-08-29
On 08/28/2013 09:11 PM, Jim Thompson wrote:> On Wed, 28 Aug 2013 20:36:20 -0400, Phil Hobbs > <pcdhSpamMeSenseless@electrooptical.net> wrote: > >> On 8/28/2013 7:37 PM, John Larkin wrote: >>> On Wed, 28 Aug 2013 22:55:24 +0000, chris <meru@devnull.com> wrote: >>> >>>> On 08/28/13 17:53, Jim Thompson wrote: >>>> >>>>> >>>>> 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 >>>> >>>> Anyone remember the GE "back" diodes ?. Same can as their tunnel diodes, >>>> but, iirc, very low forward voltage... >>>> >>>> Chris >>> >>> People still make Ge back diodes, as rf detectors. They are, I think, >>> the only planar "ic" type fabrication done in germanium, except >>> photodiodes maybe. >>> >>> http://www.aeroflex.com/AMS/Metelics/pdfiles/MBD_Series_Planar_Back_Tunnel_Diodes.pdf >>> >>> They conduct better in the reverse direction than forward, hence the >>> name. >> >> Making an AM detector that has both good linearity and a reasonable >> dynamic range is one of those deceptively hard problems. >> >> I tend to do one of two things: one or more DLVAs (e.g. SA614s) with >> some auxiliary calibrator, such as a crystal ringing down, or a PLL with >> fairly careful offset nulling. >> >> Ring-down calibration is convenient, because your average 80 MHz crystal >> rings down at something like 1 dB/ms or a bit less. You can anchor the >> high-amplitude end with linear measurements, and rely on the exponential >> falloff for the lower-amplitude range. >> >> Cheers >> >> Phil Hobbs > > Does anyone actually use just a diode for AM detection anymore? > > ...Jim Thompson >Diodes aren't so bad if you have reasonably quick AGC, and they avoid some of the misbehaviour you can get with things like active peak detectors, e.g. subharmonics and limit cycles. Plus they go a lot faster than most ICs, e.g. 18 GHz back diode detectors. (I made some at 200 THz a few years back, but their nonlinearity was only a few percent. Diodes like that can produce >200 GHz at their output terminals. I'm hoping to have a chance to revisit that later this year, but we'll see in a week or two--it's hard to get signatures during the summer.) Cheers Phil Hobbs -- 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
