Unusual functions of cheap parts
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From: Rich Grise on 30 Nov 2005 22:28 On Wed, 30 Nov 2005 17:11:17 -0500, Spehro Pefhany wrote: > On Wed, 30 Nov 2005 21:57:50 GMT, the renowned Rich Grise > <rich(a)example.net> wrote: > >>On Wed, 30 Nov 2005 15:09:49 -0500, Spehro Pefhany wrote: >> >>> On Wed, 30 Nov 2005 18:23:05 GMT, the renowned Rich Grise >>> <rich(a)example.net> wrote: >>> >>>>On Tue, 29 Nov 2005 18:00:50 +0100, Henning Paul wrote: >>>> >>>>> Spehro Pefhany schrieb: >>>>> >>>>>> I think I remember something like that, maybe with ground beef. >>>>> >>>>> You mean Labskaus? >>>>> http://en.wikipedia.org/wiki/Labskaus >>>>> >>>>> Here in Bremen/Germany we usually leave away the fish and use just Corned >>>>> Beef (the brazilian Corned Beef is just fine). And sometimes, you find >>>>> diced pickles in it. Tastes even better, then. >>>> >>>>Looks a lot like ordinary corned beef hash to me, if a little less >>>>coarsely chopped. >>>> >>>>But I wonder why they serve it with one of these? >>>> >>>>http://www2.catalognavigator.com/libertyindustries/viewitems/tacky-mats/hand-held-tacky-roll-mop?plpver=1001 >>>> >>>>;-) >>>>Rich >>> >>> You could also serve with one of these: >>> >>> http://upload.wikimedia.org/wikipedia/commons/5/50/BismarckArbeitszimmer1886.jpg >>> >>> >>From a cursory search, it looks like it'd be kinda hard to find one >>these days. ;-) >> >>Cheers! >>Rich > > He looks like this these days: > > http://www.gdh-imports.com/acatalog/04GE01.jpg > I was thinking of the "bismark roll", which I had thought was some kind of jelly donut, or "bismark donut", which would be like a jelly roll. But I can't find a single reference to the thing except at the wikipedia disambiguator page, and all it has is the blurb, something like what I said. Oh, well. :-) Thanks! Rich
From: Henry Kiefer on 1 Dec 2005 04:07 Thank you Jim for your longly explanations. I already knew the charge storage process, but the phasing aspect was new and interesting. My question about phase delay was in another direction. To be concrete: How to delay (=phase shift) a 145MegHz signal (mostly sinus waveform) with a snap diode? After reading your explanation I cannot see how to achieve a non-snapping action here. Maybe that would work with the diode if you modulate it with dc current getting delay in the ps timescale. Another question would be if it possible with the snap diode to make a power amp in some form of ringing oscillator. Of course, it should be modulable at least with FM. - Henry "RST Engineering" <jim(a)rstengineering.com> schrieb im Newsbeitrag news:11ornbrrr5mv976(a)corp.supernews.com... > A step-recovery ("snap") diode works on the principle of stored charge in > the diode. During the forward biased half of the AC waveform, the diode is > a very low impedance and it stores excess charge; during the reverse biased > half of the waveform, the diode remains a low impedance until the stored > charge is depleted, at which time the diode "snaps" into high impedance. > This snap acts much like a spark-gap transmitter, in that a tremendous > number of higher order harmonics are generated. In general (and there are > ways to enhance this), the power available from any harmonic is around 1/n * > Pin, where n is the order of the harmonic and Pin is the RF power input to > the diode. > > Biasing the diode simply varies the point on the reverse cycle of the AC > waveform where the diode snaps. For maximum power, you try to get the diode > to snap at the peak of the waveform. However, by varying the diode bias, > you can get it to snap before or after the peak of the waveform. Generally > you can get it to snap plus or minus about 30 degrees about the peak before > the snap action degrades. > > 60 degrees of phase shift is nothing to talk about unless you are working > with the 10th harmonic, which means a phase shift of 600 degrees. Now > you've got something to work with. > > Jim > >
From: Jim Thompson on 1 Dec 2005 10:05 On 30 Nov 2005 18:46:34 -0800, Winfield Hill <Winfield_member(a)newsguy.com> wrote: >Winfried Salomon wrote... >> Jorgen Lund-Nielsen wrote: >>> Winfried Salomon wrote: >>> >>>> btw, do you know a standard complementary pnp-transistor for the >>>> 2N2369, such like 2N3905 but with higher ft and less feedback >>>> capacitance? It seems that the manufactorers have almost no data >>>> on their internet pages. >>> >>> Maybe 2N4261? Have not looked into the datasheet, but as i remember, >>> i have seen them sometimes in complementary with the 2N2369 > > That was a high-frequency part for the time, spec'd at 1200MHz... > >> the problem is, that it is an rf-transistor and can't be driven at >> 30V/0.2A, I found a complementary in an old table KTT, the 2N2894A, >> but it also has max. 12V, so I find no other than the 2N3906. > > An old Raytheon datasheet says the 2N2894 was doped with platinum. > [snip] Thanks for tracking that down, Win! Gold in a PNP was certainly troubling my ancient remembrance of semiconductor chemistry. ...Jim Thompson -- | James E.Thompson, P.E. | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona Voice:(480)460-2350 | | | E-mail Address at Website Fax:(480)460-2142 | Brass Rat | | http://www.analog-innovations.com | 1962 | I love to cook with wine. Sometimes I even put it in the food.
From: John Larkin on 18 Dec 2005 16:04 On Sun, 18 Dec 2005 21:33:52 +0100, Rolf_B <rolfnospambombach(a)bluewin.ch> wrote: >John Larkin wrote: >> >> A 1N4007 can also be used as a drift step-recovery diode and as a >> plasma avalanche diode. Together, two can generate a kilovolt edge >> with a 100 ps risetime. > >Very interesting. The 1N4007 seem to be very versatile devices. >They are available with a SOD-57 glass envelope, too (1N4007G?). >These are fairly well photoconductive. When illuminated by >a high efficiency IR LED (HSDL-4230 or so) current transfer >ratios of 0.001 can be achieved. Not too much, but with >two LEDs 100uA of photocurrent is obtainable. This is OK for >a pass element in an "electrostatic" power supply for e.g. >electron or ion lens systems. A high-voltage optocoupler; cool. I've posted a schematic for a hv opamp (400 v p-p) that uses two optoisolators as the output push-pull stage... it's very cheap and simple. A higher-voltage photodetector, like a glass power diode, sounds useful, too. I worked once with a company in Southern California that had a neat gadget: it was a truncated cone of silicon with gold contacts on the base and the flattened apex. It would stand off something like 5KV until you whacked it from above with a laser, illuminating all the sides of the cone, whence it would conduct hard. I think they went out of business, though; it was pretty obscure. John
From: Winfield Hill on 18 Dec 2005 22:38
Rolf_B wrote... > > Very interesting. The 1N4007 seem to be very versatile devices. > They are available with a SOD-57 glass envelope, too (1N4007G?). > These are fairly well photoconductive. When illuminated ... While many companies* are making 1n4007G glass-passivated diodes, it appears they all cover the glass with plastic. I wonder... where one can get a 1n4007 with an all-glass package these days? * Including unusual semiconductor manufacturers, like: Won-Top, Bytesonic, Leshan Radio, Formosa Microsemi, Gulf Semiconductor, Dachang Electronic, Goodwork Semiconductor, etc. -- Thanks, - Win |