Interesting TIA design
in [Design]
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From: Phil Hobbs on 25 Oct 2009 13:52 Joerg wrote: > Phil Hobbs wrote: >> Joerg wrote: >>> Phil Hobbs wrote: <snip> >> About the only jellybean left that I know of is the >> SA605/615, and those have gone up in price by a lot. Those also have >> two IF stages, and you have to get the interstage attenuation just >> right for the RSSI curve to come out straight, with no cliffs or >> plateaus. > > > Yeah, they priced those right out of the market. Beats me why. There are > always chips like the TDA7210 but who knows when the last order bell > ringeth. > > Another option that won't go away any time soon is WWVB receivers chips. > Many have a peak output which can be used to extract the pilot tone > level. It's really meant to set the AGC time constant but there ain't no > law against other uses. This one is IMHO too expensive and just meant as > an example because it has a little more meat in the datasheet: > > http://www.c-max-time.com/downloads/getFile.php?id=533 > > Possibly the CR output of this one works: > > http://www.gsg-asia.com/ic_data_sheet/ak2125.pdf > > The Asian ones often come with a very skimpy datasheet so essentially > you'd have to buy a few and try it out. Since your client is in Asia > they should be able to obtain them for you. While they were made to work > on 60kHz or 77.5kHz that doesn't mean they won't work at a few hundred > kHz. It's just that they are sold for "atomic clocks". Meaning Walmart > pricing :-) Interesting, thanks. I hadn't thought of those. > Also, you don't need crystal filtering for your purpose if the area > around the pilot is quiet enough. Later when such a scheme works you can > typicaly buy the bare bones bond versions that reside under a tar blob. "Chip in crud" construction. Cheap, works, but *blech*. Not to bite the hand that feeds, you understand.... <snip> > >> Problem with DBMs as attenuators is linearity. You can linearize a >> diff pair with a couple of auxiliary diode-connected transistors (a la >> LM13700 input structure). Of course a pilot tone doesn't have much to >> intermodulate with until it gets into the signal path, so that would >> work fine here too. (I was thinking more of something like a BCV61C >> dual BJT.) >> > > You'd have to set the pilot where there is the least in intermodulation. > That is where my old millimeter-grid pad usually comes out. I just got a career's worth of Clearprint vellum on eBay. Much nicer than my old stuff--with that and an electric eraser, my schematics look like I never make mistakes. ;) >> We need a white board and a keg to do this really right, but it's fun >> even at a distance. >> > > Maybe a keg of Yuengling or some of the other good stuff you guys have > over on the east coast. Captain Lawrence Liquid Gold is the current local microbrew favourite. The Captain's is about 3 miles from my house. And of course everyone needs a kegerator for the lab. ;) > I really, really miss my white board. Even just for myself. No space for > it in this office and in the garage I'd only have maybe 2-3 months out > of a year. All other times you'd either get heat stroke or freeze. > I'm thinking of getting one and mounting it on hinges across my bookshelf, so that it opens like a cupboard door. It would have to be reasonably lightweight, though. 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: Jim Thompson on 25 Oct 2009 14:16 On Sun, 25 Oct 2009 13:52:45 -0400, Phil Hobbs <pcdhSpamMeSenseless(a)electrooptical.net> wrote: >Joerg wrote: [snip] > >> I really, really miss my white board. Even just for myself. No space for >> it in this office and in the garage I'd only have maybe 2-3 months out >> of a year. All other times you'd either get heat stroke or freeze. >> >I'm thinking of getting one and mounting it on hinges across my >bookshelf, so that it opens like a cupboard door. It would have to be >reasonably lightweight, though. > >Cheers > >Phil Hobbs Excellent idea. I had a white-board at the old house, in fact I had two. Here with (artistic architecture ;-) 6 wall faces in the office, no large-enough wall area left for a white board. ...Jim Thompson -- | James E.Thompson, CTO | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona 85048 Skype: Contacts Only | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at http://www.analog-innovations.com | 1962 | With Half My Brain Tied Behind My Back Still More Clever Than Mr.Prissy Pants
From: John Larkin on 25 Oct 2009 14:35 On Sun, 25 Oct 2009 13:52:45 -0400, Phil Hobbs <pcdhSpamMeSenseless(a)electrooptical.net> wrote: >Joerg wrote: >> Phil Hobbs wrote: >>> Joerg wrote: >>>> Phil Hobbs wrote: ><snip> >>> About the only jellybean left that I know of is the >>> SA605/615, and those have gone up in price by a lot. Those also have >>> two IF stages, and you have to get the interstage attenuation just >>> right for the RSSI curve to come out straight, with no cliffs or >>> plateaus. >> >> >> Yeah, they priced those right out of the market. Beats me why. There are >> always chips like the TDA7210 but who knows when the last order bell >> ringeth. >> >> Another option that won't go away any time soon is WWVB receivers chips. >> Many have a peak output which can be used to extract the pilot tone >> level. It's really meant to set the AGC time constant but there ain't no >> law against other uses. This one is IMHO too expensive and just meant as >> an example because it has a little more meat in the datasheet: >> >> http://www.c-max-time.com/downloads/getFile.php?id=533 >> >> Possibly the CR output of this one works: >> >> http://www.gsg-asia.com/ic_data_sheet/ak2125.pdf >> >> The Asian ones often come with a very skimpy datasheet so essentially >> you'd have to buy a few and try it out. Since your client is in Asia >> they should be able to obtain them for you. While they were made to work >> on 60kHz or 77.5kHz that doesn't mean they won't work at a few hundred >> kHz. It's just that they are sold for "atomic clocks". Meaning Walmart >> pricing :-) > >Interesting, thanks. I hadn't thought of those. > > >> Also, you don't need crystal filtering for your purpose if the area >> around the pilot is quiet enough. Later when such a scheme works you can >> typicaly buy the bare bones bond versions that reside under a tar blob. > >"Chip in crud" construction. Cheap, works, but *blech*. Not to bite >the hand that feeds, you understand.... > ><snip> >> >>> Problem with DBMs as attenuators is linearity. You can linearize a >>> diff pair with a couple of auxiliary diode-connected transistors (a la >>> LM13700 input structure). Of course a pilot tone doesn't have much to >>> intermodulate with until it gets into the signal path, so that would >>> work fine here too. (I was thinking more of something like a BCV61C >>> dual BJT.) >>> >> >> You'd have to set the pilot where there is the least in intermodulation. >> That is where my old millimeter-grid pad usually comes out. > >I just got a career's worth of Clearprint vellum on eBay. Much nicer >than my old stuff--with that and an electric eraser, my schematics look >like I never make mistakes. ;) > >>> We need a white board and a keg to do this really right, but it's fun >>> even at a distance. >>> >> >> Maybe a keg of Yuengling or some of the other good stuff you guys have >> over on the east coast. > >Captain Lawrence Liquid Gold is the current local microbrew favourite. >The Captain's is about 3 miles from my house. And of course everyone >needs a kegerator for the lab. ;) > >> I really, really miss my white board. Even just for myself. No space for >> it in this office and in the garage I'd only have maybe 2-3 months out >> of a year. All other times you'd either get heat stroke or freeze. >> >I'm thinking of getting one and mounting it on hinges across my >bookshelf, so that it opens like a cupboard door. It would have to be >reasonably lightweight, though. > A good whiteboard can add 10 points to one's IQ. I have one next to my workbench, so I can make measurements, take data, edit schematics, and make notes and then photograph the board, the test setup, and waveforms. ftp://jjlarkin.lmi.net/DSC01371.JPG ftp://jjlarkin.lmi.net/99S260A.JPG We assign interesting prototypes and breadboards a 99-series drawing number and informally release the pics and whatever to a server, where the data is available to everyone and officially backed up. Beats losing stuff or hiding it in someone's notebook. I also draw block diagrams and schematics on a whiteboard, and include photos of them in proposals. Customers don't seem to mind. John
From: Charlie E. on 26 Oct 2009 12:45 On Sun, 25 Oct 2009 11:16:19 -0700, Jim Thompson <To-Email-Use-The-Envelope-Icon(a)My-Web-Site.com> wrote: >On Sun, 25 Oct 2009 13:52:45 -0400, Phil Hobbs ><pcdhSpamMeSenseless(a)electrooptical.net> wrote: > >>Joerg wrote: >[snip] >> >>> I really, really miss my white board. Even just for myself. No space for >>> it in this office and in the garage I'd only have maybe 2-3 months out >>> of a year. All other times you'd either get heat stroke or freeze. >>> >>I'm thinking of getting one and mounting it on hinges across my >>bookshelf, so that it opens like a cupboard door. It would have to be >>reasonably lightweight, though. >> >>Cheers >> >>Phil Hobbs > >Excellent idea. I had a white-board at the old house, in fact I had >two. Here with (artistic architecture ;-) 6 wall faces in the office, >no large-enough wall area left for a white board. > > ...Jim Thompson Maybe find some sliding closet door hardware, so you can just slide them back and forth. I have three bookcases in my office here that would be ideal with that sort of arrangement. it would even hide the mess of the bookcases behind them... ;-) Charlie
From: Jim Thompson on 26 Oct 2009 13:21
On Mon, 26 Oct 2009 09:45:54 -0700, Charlie E. <edmondson(a)ieee.org> wrote: >On Sun, 25 Oct 2009 11:16:19 -0700, Jim Thompson ><To-Email-Use-The-Envelope-Icon(a)My-Web-Site.com> wrote: > >>On Sun, 25 Oct 2009 13:52:45 -0400, Phil Hobbs >><pcdhSpamMeSenseless(a)electrooptical.net> wrote: >> >>>Joerg wrote: >>[snip] >>> >>>> I really, really miss my white board. Even just for myself. No space for >>>> it in this office and in the garage I'd only have maybe 2-3 months out >>>> of a year. All other times you'd either get heat stroke or freeze. >>>> >>>I'm thinking of getting one and mounting it on hinges across my >>>bookshelf, so that it opens like a cupboard door. It would have to be >>>reasonably lightweight, though. >>> >>>Cheers >>> >>>Phil Hobbs >> >>Excellent idea. I had a white-board at the old house, in fact I had >>two. Here with (artistic architecture ;-) 6 wall faces in the office, >>no large-enough wall area left for a white board. >> >> ...Jim Thompson > >Maybe find some sliding closet door hardware, so you can just slide >them back and forth. I have three bookcases in my office here that >would be ideal with that sort of arrangement. it would even hide the >mess of the bookcases behind them... ;-) > >Charlie Good idea! ...Jim Thompson -- | James E.Thompson, CTO | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona 85048 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. |