Unusual functions of cheap parts
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From: mroberds on 19 Dec 2005 02:25 In sci.electronics.components Winfield Hill <Winfield_member(a)newsguy.com> wrote: >Rolf_B wrote... >> [1N4007] are available with a SOD-57 glass envelope, too (1N4007G?). >> These are fairly well photoconductive. > > 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? I've got a few 1N4003 and 1N4004 diodes with all-glass packages but I'm not sure how recent they are. They have the (older?) Fairchild logo of an italicized "F" with the middle stroke extending on both sides of the vertical. I'm about 90% sure these came in one of those "20 rectifiers for $2" packages from Rat Shock, so who knows how old they really are. The bodies are about 2.5 mm diameter by 4 mm long. Inside the glass, the ends near the leads are orange, with a clear strip less than 0.5 mm wide near the middle. Testing them with the "diode check" on a $40 multimeter and either a 40 watt clear globe lamp or a TV remote control doesn't show much photoconductivity, but I suspect I would need to look a little harder than this to see it. Matt Roberds
From: Michael A. Terrell on 19 Dec 2005 10:47 Winfield Hill wrote: > > 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 How many do you need, and can you use ones pulled from PC boards? I may have some left that I pulled from damaged boards. -- Been there, Done that, I've got my DD214 to prove it. Michael A. Terrell Central Florida
From: Henry Kiefer on 20 Dec 2005 18:31 I thought optical triggered GTOs were still in business?? regards - Henry "John Larkin" <jjlarkin(a)highNOTlandTHIStechnologyPART.com> schrieb im Newsbeitrag news:1bjbq19ncb6bmkrb4v9n85687s3ro2btcc(a)4ax.com... > 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: John Larkin on 20 Dec 2005 19:50 On Wed, 21 Dec 2005 00:31:35 +0100, "Henry Kiefer" <otc_friend(a)gmx.net> wrote: >I thought optical triggered GTOs were still in business?? > >regards - >Henry > Maybe so, but this wasn't a GTO, it was a bulk-effect device, blindingly fast. Can an opto-triggered GTO be turned *off* with light? John
From: Winfield Hill on 20 Dec 2005 20:14
Michael A. Terrell wrote... > > How many do you need, and can you use ones pulled from PC boards? > I may have some left that I pulled from damaged boards. One or two may be enough for proof-of-principle measurements. -- Thanks, - Win |