Rectify 500MHz Small Signal
in [Design]
|
From: John Larkin on 29 Sep 2009 14:33 On Tue, 29 Sep 2009 10:56:28 -0700, Joerg <invalid(a)invalid.invalid> wrote: >Phil Hobbs wrote: >> John Larkin wrote: >>> On Tue, 29 Sep 2009 09:25:15 -0700, Joerg <invalid(a)invalid.invalid> >>> wrote: >>> >>>> John Larkin wrote: > >[...] > >>>>> Oh, here it is... >>>>> >>>>> 229-1769 DIO SRD 30V SOT23 150PS MA44769 1PF >>>>> >>>>> MA44769-287 PENSTOCK >>>>> >>>>> Price 58 cents in small quantities. >>>>> >>>>> They also have MA44767-287, 600 ps risetime, a little easier to drive >>>>> because it stores more charge. >>>>> >>>>> These make nice edge generators and frequency multipliers. I have a >>>>> rubidium clock that generates the 6.3846826128 GHz frequency from a 10 >>>>> MHz rock with an absurdly small number of cheap parts. >>>>> >>>> Thanks, John! That's a decent price. And thanks for the SASE offer, >>>> but maybe I'll combine that with a beer at Zeitgeist when I get down >>>> there :-) >>> >>> Well, drop in. We have a zillion exotic parts in stock. And the >>> quality of Z's burgers has improved radically lately. Only biker bar I >>> know of with Chimay on tap. >>> > >Burgers and Chimay on tap? My kind of bar, have to get down there. > > >>>> As a kid I grew up in Europe and back then such exotic parts were >>>> very hard to find over there, even at hamfests. >>> >>> We were lucky. Tons of exotic surplus gear, lots of old teevees, >>> Allied and Lafayette and Fair Radio Sales mail-order available to >>> anyone, local distributors for over-the-counter transistors and >>> 10-turn pots and such... the counter guys gave me more parts than I >>> ever paid for. I made a deal with my parents to dump my allowance in >>> favor of a revolving credit account with Allied, so I could just order >>> stuff. I made spending money fixing radios and TVs. >>> > >Same here, fixing stuff. Provided more learning experience than many >university courses. And some money or beer, you didn't have to wait >until 21 for that in Europe :-) Didn't in New Orleans, either! John
From: Phil Hobbs on 29 Sep 2009 14:42 Joerg wrote: > Phil Hobbs wrote: >> Jan Panteltje wrote: >>> On a sunny day (Tue, 29 Sep 2009 09:34:08 -0700) it happened Joerg >>> <invalid(a)invalid.invalid> wrote in <7ier86F30e1vkU1(a)mid.individual.net>: >>> >>>>> UJTs are cool. >>>> >>>> Well, yeah, but you probably lived in the Netherlands as a kid. You >>>> guys had dump handelaars and all sorts of electronics places. UJTs >>>> were unobtanium in Germany. Once in a while we'd mount a car and >>>> head over the border. But since I was a kid back then and didn't >>>> have my own car I'd have to hitch a ride. We usually split the cost >>>> for gas and then it was affordable for everyone, but you needed a >>>> whole day. >>>> >>>> Later I lived in Zuid Limburg and with a stiff bicycle ride you >>>> could haul stuff home from the surplus dealer in Margraten. Wrecked >>>> many baggage racks that way, plus some chains, axles and so on. And >>>> found out the hard way that bicycle brakes don't work so good with >>>> 50 pounds of stuff on the back. >>> >>> Still widely available, I used the 2N2646: >>> http://nl.farnell.com/unijunction-transistors-ujt >> >> I like PUTs for things like laser interlocks. Unlike ICs, I know >> exactly how they'll behave in fault conditions, which matters a lot. >> Relays are good too. >> > > Thanks. AFAICT the 2646 has long since been obsoleted, maybe still > considered by boutique mfgs. When I was young I was always told "We can > order it but that'll really cost ya". I didn't know you could still get > the 6027 although the fact that it was never migrated to SMT doesn't > bode well for its future. > > Personally I have never seen a design that contained a UJT, this > technology may have played chicken and egg for too long. > For my purposes the two-BJT SCR works fine too. Doesn't have to be fast, just very reliable and predictable. Cheers Phil Hobbs -- Dr Philip C D Hobbs Principal ElectroOptical Innovations 55 Orchard Rd Briarcliff Manor NY 10510 845-480-2058 hobbs at electrooptical dot net http://electrooptical.net
From: Phil Hobbs on 29 Sep 2009 14:41 John Larkin wrote: > On Tue, 29 Sep 2009 13:34:14 -0400, Phil Hobbs > <pcdhSpamMeSenseless(a)electrooptical.net> wrote: > >> John Larkin wrote: >>> On Tue, 29 Sep 2009 09:25:15 -0700, Joerg <invalid(a)invalid.invalid> >>> wrote: >>> >>>> John Larkin wrote: >>>>> On Mon, 28 Sep 2009 17:43:22 -0700, Joerg <invalid(a)invalid.invalid> >>>>> wrote: >>>>> >>>>>> John Larkin wrote: >>>>>>> On Mon, 28 Sep 2009 20:05:23 -0400, Phil Hobbs >>>>>>> <pcdhSpamMeSenseless(a)electrooptical.net> wrote: >>>>>>> >>>>>>>> John Fields wrote: >>>>>>>>> On Mon, 28 Sep 2009 10:25:05 -0700, John Larkin >>>>>>>>> <jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote: >>>>>>>>> >>>>>>>>>> On Sat, 26 Sep 2009 17:58:27 -0700, Archimedes' Lever >>>>>>>>>> <OneBigLever(a)InfiniteSeries.Org> wrote: >>>>>>>>>> >>>>>>>>>>> On Sat, 26 Sep 2009 16:52:40 -0700, John Larkin >>>>>>>>>>> <jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote: >>>>>>>>>>> >>>>>>>>>>>> On Sat, 26 Sep 2009 17:28:50 -0400, "Michael A. Terrell" >>>>>>>>>>>> <mike.terrell(a)earthlink.net> wrote: >>>>>>>>>>>> >>>>>>>>>>>>> John Larkin wrote: >>>>>>>>>>>>>> There's the slideback technique: drive a comparator with RF on one >>>>>>>>>>>>>> side, DC feedback on the other. Tease the DC appropriately. >>>>>>>>>>>>>> >>>>>>>>>>>>>> I once made a slideback sampling oscilloscope, using tunnel diodes, as >>>>>>>>>>>>>> my EE senior project. I won an award and had to attend a dreadful IEEE >>>>>>>>>>>>>> chapter banquet and repeat it to a bunch of old-fart power engineers >>>>>>>>>>>>>> who didn't understand a word I said. I described the slideback >>>>>>>>>>>>>> sampling scope in this ng some years back and a certain party loved >>>>>>>>>>>>>> the idea so much he later decided that he'd invented it himself. >>>>>>>>>>>>> <http://store.americanmicrosemiconductor.com/diodes-tunnel-diodes.html> >>>>>>>>>>>> TDs are insanely expensive nowadays, ballpark $100. I used to get them >>>>>>>>>>>> for a couple bucks from Allied. The fabrication process is insane, and >>>>>>>>>>>> nobody ever modernized it. >>>>>>>>>>>> >>>>>>>>>>>> There are some more modern planar germanium back diodes, essentially >>>>>>>>>>>> low Ip tunnel diodes, but they're RF detectors, useless for switching. >>>>>>>>>>>> Pity, I used to like tunnel diodes. >>>>>>>>>>>> >>>>>>>>>>>> http://aeroflex.com/AMS/Metelics/pdfiles/MBD_Series_Planar_Back_Tunnel_Diodes.pdf >>>>>>>>>>>> >>>>>>>>>>>> John >>>>>>>>>>> Try PiN diodes then. >>>>>>>>>> For what? Certainly not switching, amplifying, oscillating, detection, >>>>>>>>>> or mixing. >>>>>>>>> --- >>>>>>>>> Re. switching, From: >>>>>>>>> >>>>>>>>> http://en.wikipedia.org/wiki/PIN_diode >>>>>>>>> >>>>>>>>> "Under zero or reverse bias, a PIN diode has a low capacitance. The low >>>>>>>>> capacitance will not pass much of an RF signal. Under a forward bias of >>>>>>>>> 1 mA, a typical PIN diode will have an RF resistance of about 1 ohm, >>>>>>>>> making it a good RF conductor. Consequently, the PIN diode makes a good >>>>>>>>> RF switch." >>>>>>>>> --- >>>>>>>> Good, but not fast. PIN diodes specialize in having a lot of stored >>>>>>>> charge, so that the signal current can be quite a bit larger than the DC >>>>>>>> current without causing excessive distortion. >>>>>>>> >>>>>>>> Cheers >>>>>>>> >>>>>>>> Phil Hobbs >>>>>>> PINs stop behaving like PINs at low frequencies, too. So they don't >>>>>>> make useful wideband switches. >>>>>>> >>>>>> Got to watch the carrier lifetime. The lower the bottom of your spectrum >>>>>> and the higher the RF current, the longer its carrier lifetime must be. >>>>>> I found PIN diodes to be great and most of all cheap variable >>>>>> attenuators as well as switched. Designed in tons of them. >>>>>> >>>>>> >>>>>>> But I meant active switching when I was referring to a TD. A TD would >>>>>>> *generate* a fast step from an arbitrarily slow drive. >>>>>>> >>>>>> I've drooled over SRDs all my life and every time I wanted to buy one I >>>>>> either couldn't have one or it was outlandishly expensive. Guess >>>>>> avalanching is the only game in town and if you want avalanche-rated >>>>>> then a bone-simple BJT can easily shoot up to twenty bucks. >>>>> SRDs aren't hard to get. MA/Com has distributor parts, under a buck. >>>>> M-Pulse and Metelics are good about samples. If you want a few, send >>>>> me a SASE. >>>>> >>>>> Oh, here it is... >>>>> >>>>> 229-1769 DIO SRD 30V SOT23 150PS MA44769 1PF >>>>> >>>>> MA44769-287 PENSTOCK >>>>> >>>>> Price 58 cents in small quantities. >>>>> >>>>> They also have MA44767-287, 600 ps risetime, a little easier to drive >>>>> because it stores more charge. >>>>> >>>>> These make nice edge generators and frequency multipliers. I have a >>>>> rubidium clock that generates the 6.3846826128 GHz frequency from a 10 >>>>> MHz rock with an absurdly small number of cheap parts. >>>>> >>>> Thanks, John! That's a decent price. And thanks for the SASE offer, but >>>> maybe I'll combine that with a beer at Zeitgeist when I get down there :-) >>> Well, drop in. We have a zillion exotic parts in stock. And the >>> quality of Z's burgers has improved radically lately. Only biker bar I >>> know of with Chimay on tap. >>> >>>> As a kid I grew up in Europe and back then such exotic parts were very >>>> hard to find over there, even at hamfests. >>> We were lucky. Tons of exotic surplus gear, lots of old teevees, >>> Allied and Lafayette and Fair Radio Sales mail-order available to >>> anyone, local distributors for over-the-counter transistors and >>> 10-turn pots and such... the counter guys gave me more parts than I >>> ever paid for. I made a deal with my parents to dump my allowance in >>> favor of a revolving credit account with Allied, so I could just order >>> stuff. I made spending money fixing radios and TVs. >>> >>> John >>> >> Still not as good as now. I just bought an excellent-condition HP 8568B >> spectrum analyzer for $900. About 2 cents on the dollar. So far this >> year I've bought test equipment that would have cost way over $100000 >> new, for probably $4k altogether. Amazing. >> >> Cheers >> >> Phil Hobbs > > And I'm looking at, theoretically, a quarter million dollars worth of > sampling heads over there on my shelf. This is an amazing time to > start a niche business, or even an exotic hobby. > > John > Funny you should mention that. ;) Cheers Phil Hobbs -- Dr Philip C D Hobbs Principal ElectroOptical Innovations 55 Orchard Rd Briarcliff Manor NY 10510 845-480-2058 hobbs at electrooptical dot net http://electrooptical.net
From: Joerg on 29 Sep 2009 15:53 John Larkin wrote: > On Tue, 29 Sep 2009 13:34:14 -0400, Phil Hobbs > <pcdhSpamMeSenseless(a)electrooptical.net> wrote: > >> John Larkin wrote: >>> On Tue, 29 Sep 2009 09:25:15 -0700, Joerg <invalid(a)invalid.invalid> >>> wrote: >>> >>>> John Larkin wrote: >>>>> On Mon, 28 Sep 2009 17:43:22 -0700, Joerg <invalid(a)invalid.invalid> >>>>> wrote: >>>>> >>>>>> John Larkin wrote: >>>>>>> On Mon, 28 Sep 2009 20:05:23 -0400, Phil Hobbs >>>>>>> <pcdhSpamMeSenseless(a)electrooptical.net> wrote: >>>>>>> >>>>>>>> John Fields wrote: >>>>>>>>> On Mon, 28 Sep 2009 10:25:05 -0700, John Larkin >>>>>>>>> <jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote: >>>>>>>>> >>>>>>>>>> On Sat, 26 Sep 2009 17:58:27 -0700, Archimedes' Lever >>>>>>>>>> <OneBigLever(a)InfiniteSeries.Org> wrote: >>>>>>>>>> >>>>>>>>>>> On Sat, 26 Sep 2009 16:52:40 -0700, John Larkin >>>>>>>>>>> <jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote: >>>>>>>>>>> >>>>>>>>>>>> On Sat, 26 Sep 2009 17:28:50 -0400, "Michael A. Terrell" >>>>>>>>>>>> <mike.terrell(a)earthlink.net> wrote: >>>>>>>>>>>> >>>>>>>>>>>>> John Larkin wrote: >>>>>>>>>>>>>> There's the slideback technique: drive a comparator with RF on one >>>>>>>>>>>>>> side, DC feedback on the other. Tease the DC appropriately. >>>>>>>>>>>>>> >>>>>>>>>>>>>> I once made a slideback sampling oscilloscope, using tunnel diodes, as >>>>>>>>>>>>>> my EE senior project. I won an award and had to attend a dreadful IEEE >>>>>>>>>>>>>> chapter banquet and repeat it to a bunch of old-fart power engineers >>>>>>>>>>>>>> who didn't understand a word I said. I described the slideback >>>>>>>>>>>>>> sampling scope in this ng some years back and a certain party loved >>>>>>>>>>>>>> the idea so much he later decided that he'd invented it himself. >>>>>>>>>>>>> <http://store.americanmicrosemiconductor.com/diodes-tunnel-diodes.html> >>>>>>>>>>>> TDs are insanely expensive nowadays, ballpark $100. I used to get them >>>>>>>>>>>> for a couple bucks from Allied. The fabrication process is insane, and >>>>>>>>>>>> nobody ever modernized it. >>>>>>>>>>>> >>>>>>>>>>>> There are some more modern planar germanium back diodes, essentially >>>>>>>>>>>> low Ip tunnel diodes, but they're RF detectors, useless for switching. >>>>>>>>>>>> Pity, I used to like tunnel diodes. >>>>>>>>>>>> >>>>>>>>>>>> http://aeroflex.com/AMS/Metelics/pdfiles/MBD_Series_Planar_Back_Tunnel_Diodes.pdf >>>>>>>>>>>> >>>>>>>>>>>> John >>>>>>>>>>> Try PiN diodes then. >>>>>>>>>> For what? Certainly not switching, amplifying, oscillating, detection, >>>>>>>>>> or mixing. >>>>>>>>> --- >>>>>>>>> Re. switching, From: >>>>>>>>> >>>>>>>>> http://en.wikipedia.org/wiki/PIN_diode >>>>>>>>> >>>>>>>>> "Under zero or reverse bias, a PIN diode has a low capacitance. The low >>>>>>>>> capacitance will not pass much of an RF signal. Under a forward bias of >>>>>>>>> 1 mA, a typical PIN diode will have an RF resistance of about 1 ohm, >>>>>>>>> making it a good RF conductor. Consequently, the PIN diode makes a good >>>>>>>>> RF switch." >>>>>>>>> --- >>>>>>>> Good, but not fast. PIN diodes specialize in having a lot of stored >>>>>>>> charge, so that the signal current can be quite a bit larger than the DC >>>>>>>> current without causing excessive distortion. >>>>>>>> >>>>>>>> Cheers >>>>>>>> >>>>>>>> Phil Hobbs >>>>>>> PINs stop behaving like PINs at low frequencies, too. So they don't >>>>>>> make useful wideband switches. >>>>>>> >>>>>> Got to watch the carrier lifetime. The lower the bottom of your spectrum >>>>>> and the higher the RF current, the longer its carrier lifetime must be. >>>>>> I found PIN diodes to be great and most of all cheap variable >>>>>> attenuators as well as switched. Designed in tons of them. >>>>>> >>>>>> >>>>>>> But I meant active switching when I was referring to a TD. A TD would >>>>>>> *generate* a fast step from an arbitrarily slow drive. >>>>>>> >>>>>> I've drooled over SRDs all my life and every time I wanted to buy one I >>>>>> either couldn't have one or it was outlandishly expensive. Guess >>>>>> avalanching is the only game in town and if you want avalanche-rated >>>>>> then a bone-simple BJT can easily shoot up to twenty bucks. >>>>> SRDs aren't hard to get. MA/Com has distributor parts, under a buck. >>>>> M-Pulse and Metelics are good about samples. If you want a few, send >>>>> me a SASE. >>>>> >>>>> Oh, here it is... >>>>> >>>>> 229-1769 DIO SRD 30V SOT23 150PS MA44769 1PF >>>>> >>>>> MA44769-287 PENSTOCK >>>>> >>>>> Price 58 cents in small quantities. >>>>> >>>>> They also have MA44767-287, 600 ps risetime, a little easier to drive >>>>> because it stores more charge. >>>>> >>>>> These make nice edge generators and frequency multipliers. I have a >>>>> rubidium clock that generates the 6.3846826128 GHz frequency from a 10 >>>>> MHz rock with an absurdly small number of cheap parts. >>>>> >>>> Thanks, John! That's a decent price. And thanks for the SASE offer, but >>>> maybe I'll combine that with a beer at Zeitgeist when I get down there :-) >>> Well, drop in. We have a zillion exotic parts in stock. And the >>> quality of Z's burgers has improved radically lately. Only biker bar I >>> know of with Chimay on tap. >>> >>>> As a kid I grew up in Europe and back then such exotic parts were very >>>> hard to find over there, even at hamfests. >>> We were lucky. Tons of exotic surplus gear, lots of old teevees, >>> Allied and Lafayette and Fair Radio Sales mail-order available to >>> anyone, local distributors for over-the-counter transistors and >>> 10-turn pots and such... the counter guys gave me more parts than I >>> ever paid for. I made a deal with my parents to dump my allowance in >>> favor of a revolving credit account with Allied, so I could just order >>> stuff. I made spending money fixing radios and TVs. >>> >>> John >>> >> Still not as good as now. I just bought an excellent-condition HP 8568B >> spectrum analyzer for $900. About 2 cents on the dollar. So far this >> year I've bought test equipment that would have cost way over $100000 >> new, for probably $4k altogether. Amazing. >> >> Cheers >> >> Phil Hobbs > > And I'm looking at, theoretically, a quarter million dollars worth of > sampling heads over there on my shelf. This is an amazing time to > start a niche business, or even an exotic hobby. > Is there anything available at reasonable cost that does zippy sampling without needing a Goliath of a scope attached to it? -- Regards, Joerg http://www.analogconsultants.com/ "gmail" domain blocked because of excessive spam. Use another domain or send PM.
From: Joerg on 29 Sep 2009 15:56
Phil Hobbs wrote: > Joerg wrote: >> Phil Hobbs wrote: >>> Jan Panteltje wrote: >>>> On a sunny day (Tue, 29 Sep 2009 09:34:08 -0700) it happened Joerg >>>> <invalid(a)invalid.invalid> wrote in >>>> <7ier86F30e1vkU1(a)mid.individual.net>: >>>> >>>>>> UJTs are cool. >>>>> >>>>> Well, yeah, but you probably lived in the Netherlands as a kid. You >>>>> guys had dump handelaars and all sorts of electronics places. UJTs >>>>> were unobtanium in Germany. Once in a while we'd mount a car and >>>>> head over the border. But since I was a kid back then and didn't >>>>> have my own car I'd have to hitch a ride. We usually split the cost >>>>> for gas and then it was affordable for everyone, but you needed a >>>>> whole day. >>>>> >>>>> Later I lived in Zuid Limburg and with a stiff bicycle ride you >>>>> could haul stuff home from the surplus dealer in Margraten. Wrecked >>>>> many baggage racks that way, plus some chains, axles and so on. And >>>>> found out the hard way that bicycle brakes don't work so good with >>>>> 50 pounds of stuff on the back. >>>> >>>> Still widely available, I used the 2N2646: >>>> http://nl.farnell.com/unijunction-transistors-ujt >>> >>> I like PUTs for things like laser interlocks. Unlike ICs, I know >>> exactly how they'll behave in fault conditions, which matters a lot. >>> Relays are good too. >>> >> >> Thanks. AFAICT the 2646 has long since been obsoleted, maybe still >> considered by boutique mfgs. When I was young I was always told "We >> can order it but that'll really cost ya". I didn't know you could >> still get the 6027 although the fact that it was never migrated to SMT >> doesn't bode well for its future. >> >> Personally I have never seen a design that contained a UJT, this >> technology may have played chicken and egg for too long. >> > > For my purposes the two-BJT SCR works fine too. Doesn't have to be > fast, just very reliable and predictable. > If I need a crowbar or something to that effect I usually take a regular SCR, a TL431, a transistor and some resistors. You can make that go off at rather precise levels. Impressed a client quite a bit who was used to the regular sloppy crowbars. I told them mine would trigger between 3.6V and 3.7V. "Really?" ... "Yeah". It triggered at precisely 3.65V :-) -- Regards, Joerg http://www.analogconsultants.com/ "gmail" domain blocked because of excessive spam. Use another domain or send PM. |