Rectify 500MHz Small Signal
in [Design]
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From: Phil Hobbs on 29 Sep 2009 13:29 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. 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 13:34 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 -- 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 13:56 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 :-) >> 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. > Also Digikey. Even the places John mentioned probably didn't have quite that selection. Nowadays you can buy a xxGHz BJT for a buck. Which BTW can also be used to gussy up a transition by a lot. OTOH the dire parts situation back then taught me lots of tricks and most of all, discrete design. Opamps of known origin cost several Dollars. You could get opamps of not so noble origin ("Fell off the truck" brands) for under a buck but that was really frustrating because you never knew what deficiency they'd exhibit. So I stuck with transistors because they worked. You just had to stay away from those bag-o-ten "Universal NPN transistors". -- 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 14:04 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. -- Regards, Joerg http://www.analogconsultants.com/ "gmail" domain blocked because of excessive spam. Use another domain or send PM.
From: John Larkin on 29 Sep 2009 14:32
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 |