Hi Gerhard, Gerhard Hoffmann 04:40 (vor 6 Stunden)> since you are interested in measuring small currents, you might like this one:...You provide very interesting ideas every time! I remember your amplifier attempts. Our "customers" like to see 0,5pA as resolution, not accuracy, so I'm in a relaxed situation with the ADA4350-1. Much simpler than the swiss approach. Interesting, that they seem to use ordinary FR4 instead of ceramic based layers. Congratulations, that you managed the scope fail! In earlier times we left the disco at that time, not the lab... Thank you very much! Cheers, Timo
Low noise, high bias voltage on picoAmp TIA's input, howto?
Started by ●May 21, 2021
Reply by ●May 28, 20212021-05-28
Reply by ●May 28, 20212021-05-28
On Friday, May 28, 2021 at 6:03:40 PM UTC+10, timo.k...@ibtk.de wrote:> Bill Sloman schrieb am Freitag, 28. Mai 2021 um 07:24:52 UTC+2: > > > LTSpice 17 did better, but the circuit is horribly messed up with resistors not hooked up and in the wrong place. I've made a start at making the schematic look more like something that would work, but it isn't going quickly, and the saturatable transformer model doesn't seem to have made it. > > Using the John Chan model for saturation is nice, but does it seem to make the schematic very messy. > > Using a bipolar transistor to drive the transformer may not help the efficiency - they do need base drive (though the FTZ694B is a high gain part) and they don't pull the collector as low as a good MOSFET pulls it drain, particularly when you have Schottky diodes in series with the emitters .... > > > Good morning Bill, > > excuse me please, I did not tell about usage. > You should expand the zip with another program than LTSpice and put all files in _one_ (working) directory. You may prefer a new one but not necessarily. LTSpice grabs all needed symbols from there, also the modified res.asy. > This is explained here: > https://www.mikrocontroller.net/topic/373488#4226728 > > I sent you an email containing the single files. > > The chan model or the schematics become much more clear by using the Symbols: > Trafo_1pri_1sek.asy > or > Trafo_3pri_2sek.asy > which has to carry the identical name as ist's nets: > trafo_1pri_1sek.asc > or > Trafo_3pri_2sek.ascThanks. I had to put in three ferrite beads - I picked the 1uH Wurth parts from the LTSpice list - and add a Spice model for the FTZ694B - but after that the circuit did simulate and produced sensible waveforms. I had to stretch the simulation periods out to 10msec - there was something odd happening around 2.2msec.> The model description is put into the *.asc files, the upper-/lowercase does not seem to be a problem. > > The original resistors use a bad placed origin, it should be in the middle of the symbol. Additionaly I like to know, which is pin 1 in the schematic (e.g. to determine the direction of the current flow). > > One may prove the power wasted by e.g. the bipolars using [Alt]+[left mouse button] on it. It is low in comparison to the whole efficiency loss. > If I prefer FETs, I have to watch Vgs or complicate the gate-controls due to the 24V power which translates into (Pi)*24V=75V at the drains.I agree that MOSFETs are bit trickier to drive than bipolar transistors - I tend to use a one turn base drive coil between the bases of a PNP long-tail pair, and switch the tail current between two gate to source resistors. but you typically have a 20V rating between gate and source, which allows plenty of head-room. 75V isn't a problem. The Rohm RSQ030N08HZG - at 3A peak current - is a bit bigger than you'd need, but element-14 have 102 in stock for about a dollar each. http://www.farnell.com/datasheets/2918432.pdf> I am still not sure which version would be the more suitable for that application. At least I saw the bipolar version working. ;)Bipolar transistors can give you squegging - which LT Spice doesn't simulate because it seems to depend on something odd that inverted bipolar transistors that the Gummell-Poon model doesn't capture. -- Bill Sloman, Sydney
Reply by ●May 28, 20212021-05-28
Joe Gwinn wrote:> On Thu, 27 May 2021 16:50:51 -0400, Phil Hobbs > <pcdhSpamMeSenseless@electrooptical.net> wrote: > >> timo.k...@ibtk.de wrote: >>> Hi Phil, >>> >>> excuse the delay please, I got my second vaccination 2 hours ago. >>> direct link: >>> https://de1lib.org/dl/5420567/4762b2 >>> It seems to change the hash daily (the part following last slash). >>> alternatively: >>> https://de1lib.org/book/5420567/adfe6c?id=5420567&secret=adfe6c >>> Thank you for sharing your valuable experiences! >>> >>> Cheeers, Timo >>> >> Thanks. I made an OCRed version using https://djvu.org/any2djvu, which >> seems to work fine. > > It wants a password, and my security software was wailing about it. > > Joe >No password required when I use it. Cheers Phil Hobbs -- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC / Hobbs ElectroOptics Optics, Electro-optics, Photonics, Analog Electronics Briarcliff Manor NY 10510 http://electrooptical.net http://hobbs-eo.com
Reply by ●May 28, 20212021-05-28
On Fri, 28 May 2021 10:32:27 -0400, Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:>Joe Gwinn wrote: >> On Thu, 27 May 2021 16:50:51 -0400, Phil Hobbs >> <pcdhSpamMeSenseless@electrooptical.net> wrote: >> >>> timo.k...@ibtk.de wrote: >>>> Hi Phil, >>>> >>>> excuse the delay please, I got my second vaccination 2 hours ago. >>>> direct link: >>>> https://de1lib.org/dl/5420567/4762b2 >>>> It seems to change the hash daily (the part following last slash). >>>> alternatively: >>>> https://de1lib.org/book/5420567/adfe6c?id=5420567&secret=adfe6c >>>> Thank you for sharing your valuable experiences! >>>> >>>> Cheeers, Timo >>>> >>> Thanks. I made an OCRed version using https://djvu.org/any2djvu, which >>> seems to work fine. >> >> It wants a password, and my security software was wailing about it. >> >> Joe >> > >No password required when I use it.I just checked again, got the djvu password request. You may have your credentials cached, so it doesn't keep asking you. If you come in using a private browser window, what happens? Joe Gwinn
Reply by ●May 28, 20212021-05-28
On Friday, May 28, 2021 at 11:26:41 PM UTC+10, Bill Sloman wrote:> On Friday, May 28, 2021 at 6:03:40 PM UTC+10, timo.k...@ibtk.de wrote: > > Bill Sloman schrieb am Freitag, 28. Mai 2021 um 07:24:52 UTC+2:<snip>> Thanks. I had to put in three ferrite beads - I picked the 1uH Wurth parts from the LTSpice list - and add a Spice model for the FTZ694B - but after that the circuit did simulate and produced sensible waveforms. I had to stretch the simulation periods out to 10msec - there was something odd happening around 2.2msec.<snip>> Bipolar transistors can give you squegging - which LT Spice doesn't simulate because it seems to depend on something odd that inverted bipolar transistors that the Gummell-Poon model doesn't capture.In fact, that seems to have been what was gong on from 2.0 msec to about 2.7msec. The current through L7 started going negative - to about -5mA, and there were a negative current spikes through Q1 and Q2. The problem is that this goes away in Spice simulations, but have been known to persist in real life. In real life you'd probably reduce the inductance of L7 until it went away. -- Bill Sloman, Sydney
Reply by ●May 29, 20212021-05-29
Joe Gwinn wrote:> On Fri, 28 May 2021 10:32:27 -0400, Phil Hobbs > <pcdhSpamMeSenseless@electrooptical.net> wrote: > >> Joe Gwinn wrote: >>> On Thu, 27 May 2021 16:50:51 -0400, Phil Hobbs >>> <pcdhSpamMeSenseless@electrooptical.net> wrote: >>> >>>> timo.k...@ibtk.de wrote: >>>>> Hi Phil, >>>>> >>>>> excuse the delay please, I got my second vaccination 2 hours >>>>> ago. direct link: https://de1lib.org/dl/5420567/4762b2 It >>>>> seems to change the hash daily (the part following last >>>>> slash). alternatively: >>>>> https://de1lib.org/book/5420567/adfe6c?id=5420567&secret=adfe6c >>>>> >>>>>Thank you for sharing your valuable experiences!>>>>> >>>>> Cheeers, Timo >>>>> >>>> Thanks. I made an OCRed version using >>>> https://djvu.org/any2djvu, which seems to work fine. >>> >>> It wants a password, and my security software was wailing about >>> it. >>> >>> Joe >>> >> >> No password required when I use it. > > I just checked again, got the djvu password request. > > You may have your credentials cached, so it doesn't keep asking you. > > If you come in using a private browser window, what happens? > > Joe Gwinn >Weird. If I just type djvu.org into the address bar, it comes up in http:// and works normally. The https:// thing works as you say. Use the http:// one. ;0 Cheers Phil Hobbs -- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC / Hobbs ElectroOptics Optics, Electro-optics, Photonics, Analog Electronics Briarcliff Manor NY 10510 http://electrooptical.net http://hobbs-eo.com
Reply by ●May 29, 20212021-05-29
On Sat, 29 May 2021 16:29:27 -0400, Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:>Joe Gwinn wrote: >> On Fri, 28 May 2021 10:32:27 -0400, Phil Hobbs >> <pcdhSpamMeSenseless@electrooptical.net> wrote: >> >>> Joe Gwinn wrote: >>>> On Thu, 27 May 2021 16:50:51 -0400, Phil Hobbs >>>> <pcdhSpamMeSenseless@electrooptical.net> wrote: >>>> >>>>> timo.k...@ibtk.de wrote: >>>>>> Hi Phil, >>>>>> >>>>>> excuse the delay please, I got my second vaccination 2 hours >>>>>> ago. direct link: https://de1lib.org/dl/5420567/4762b2 It >>>>>> seems to change the hash daily (the part following last >>>>>> slash). alternatively: >>>>>> https://de1lib.org/book/5420567/adfe6c?id=5420567&secret=adfe6c >>>>>> >>>>>> >Thank you for sharing your valuable experiences! >>>>>> >>>>>> Cheeers, Timo >>>>>> >>>>> Thanks. I made an OCRed version using >>>>> https://djvu.org/any2djvu, which seems to work fine. >>>> >>>> It wants a password, and my security software was wailing about >>>> it. >>>> >>>> Joe >>>> >>> >>> No password required when I use it. >> >> I just checked again, got the djvu password request. >> >> You may have your credentials cached, so it doesn't keep asking you. >> >> If you come in using a private browser window, what happens? >> >> Joe Gwinn >> > >Weird. If I just type djvu.org into the address bar, it comes up in >http:// and works normally. The https:// thing works as you say. > >Use the http:// one. ;0Using plain http did get rid of the password dialog, and did get me to the any2djvu page, which is not an OCRed copy of anything. Joe Gwinn
Reply by ●May 29, 20212021-05-29
Joe Gwinn wrote:> On Sat, 29 May 2021 16:29:27 -0400, Phil Hobbs > <pcdhSpamMeSenseless@electrooptical.net> wrote: > >> Joe Gwinn wrote: >>> On Fri, 28 May 2021 10:32:27 -0400, Phil Hobbs >>> <pcdhSpamMeSenseless@electrooptical.net> wrote: >>> >>>> Joe Gwinn wrote: >>>>> On Thu, 27 May 2021 16:50:51 -0400, Phil Hobbs >>>>> <pcdhSpamMeSenseless@electrooptical.net> wrote: >>>>> >>>>>> timo.k...@ibtk.de wrote: >>>>>>> Hi Phil, >>>>>>> >>>>>>> excuse the delay please, I got my second vaccination 2 hours >>>>>>> ago. direct link: https://de1lib.org/dl/5420567/4762b2 It >>>>>>> seems to change the hash daily (the part following last >>>>>>> slash). alternatively: >>>>>>> https://de1lib.org/book/5420567/adfe6c?id=5420567&secret=adfe6c >>>>>>> >>>>>>> >> Thank you for sharing your valuable experiences! >>>>>>> >>>>>>> Cheeers, Timo >>>>>>> >>>>>> Thanks. I made an OCRed version using >>>>>> https://djvu.org/any2djvu, which seems to work fine. >>>>> >>>>> It wants a password, and my security software was wailing about >>>>> it. >>>>> >>>>> Joe >>>>> >>>> >>>> No password required when I use it. >>> >>> I just checked again, got the djvu password request. >>> >>> You may have your credentials cached, so it doesn't keep asking you. >>> >>> If you come in using a private browser window, what happens? >>> >>> Joe Gwinn >>> >> >> Weird. If I just type djvu.org into the address bar, it comes up in >> http:// and works normally. The https:// thing works as you say. >> >> Use the http:// one. ;0 > > Using plain http did get rid of the password dialog, and did get me to > the any2djvu page, which is not an OCRed copy of anything. > > Joe Gwinn >Try it out on an actual PDF. There are several options for getting embedded text, two of which involve OCR. I've done hundreds of documents that way, from one-pagers up to full-length books. It's Good Medicine. Cheers Phil Hobbs -- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC / Hobbs ElectroOptics Optics, Electro-optics, Photonics, Analog Electronics Briarcliff Manor NY 10510 http://electrooptical.net http://hobbs-eo.com
Reply by ●May 30, 20212021-05-30
On Sat, 29 May 2021 18:24:16 -0400, Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:>Joe Gwinn wrote: >> On Sat, 29 May 2021 16:29:27 -0400, Phil Hobbs >> <pcdhSpamMeSenseless@electrooptical.net> wrote: >> >>> Joe Gwinn wrote: >>>> On Fri, 28 May 2021 10:32:27 -0400, Phil Hobbs >>>> <pcdhSpamMeSenseless@electrooptical.net> wrote: >>>> >>>>> Joe Gwinn wrote: >>>>>> On Thu, 27 May 2021 16:50:51 -0400, Phil Hobbs >>>>>> <pcdhSpamMeSenseless@electrooptical.net> wrote: >>>>>> >>>>>>> timo.k...@ibtk.de wrote: >>>>>>>> Hi Phil, >>>>>>>> >>>>>>>> excuse the delay please, I got my second vaccination 2 hours >>>>>>>> ago. direct link: https://de1lib.org/dl/5420567/4762b2 It >>>>>>>> seems to change the hash daily (the part following last >>>>>>>> slash). alternatively: >>>>>>>> https://de1lib.org/book/5420567/adfe6c?id=5420567&secret=adfe6c >>>>>>>> >>>>>>>> >>> Thank you for sharing your valuable experiences! >>>>>>>> >>>>>>>> Cheeers, Timo >>>>>>>> >>>>>>> Thanks. I made an OCRed version using >>>>>>> https://djvu.org/any2djvu, which seems to work fine. >>>>>> >>>>>> It wants a password, and my security software was wailing about >>>>>> it. >>>>>> >>>>>> Joe >>>>>> >>>>> >>>>> No password required when I use it. >>>> >>>> I just checked again, got the djvu password request. >>>> >>>> You may have your credentials cached, so it doesn't keep asking you. >>>> >>>> If you come in using a private browser window, what happens? >>>> >>>> Joe Gwinn >>>> >>> >>> Weird. If I just type djvu.org into the address bar, it comes up in >>> http:// and works normally. The https:// thing works as you say. >>> >>> Use the http:// one. ;0 >> >> Using plain http did get rid of the password dialog, and did get me to >> the any2djvu page, which is not an OCRed copy of anything. >> >> Joe Gwinn >> > >Try it out on an actual PDF. There are several options for getting >embedded text, two of which involve OCR. I've done hundreds of >documents that way, from one-pagers up to full-length books. It's Good >Medicine.Ahh. I thought that an already OCRed pdf was there. I don't have the original pdf yet. Where do I find that? Thanks, Joe Gwinn
Reply by ●May 30, 20212021-05-30
Joe Gwinn wrote:> On Sat, 29 May 2021 18:24:16 -0400, Phil Hobbs > <pcdhSpamMeSenseless@electrooptical.net> wrote: > >> Joe Gwinn wrote: >>> On Sat, 29 May 2021 16:29:27 -0400, Phil Hobbs >>> <pcdhSpamMeSenseless@electrooptical.net> wrote: >>> >>>> Joe Gwinn wrote: >>>>> On Fri, 28 May 2021 10:32:27 -0400, Phil Hobbs >>>>> <pcdhSpamMeSenseless@electrooptical.net> wrote: >>>>> >>>>>> Joe Gwinn wrote: >>>>>>> On Thu, 27 May 2021 16:50:51 -0400, Phil Hobbs >>>>>>> <pcdhSpamMeSenseless@electrooptical.net> wrote: >>>>>>> >>>>>>>> timo.k...@ibtk.de wrote: >>>>>>>>> Hi Phil, >>>>>>>>> >>>>>>>>> excuse the delay please, I got my second vaccination 2 hours >>>>>>>>> ago. direct link: https://de1lib.org/dl/5420567/4762b2 It >>>>>>>>> seems to change the hash daily (the part following last >>>>>>>>> slash). alternatively: >>>>>>>>> https://de1lib.org/book/5420567/adfe6c?id=5420567&secret=adfe6c >>>>>>>>> >>>>>>>>> >>>> Thank you for sharing your valuable experiences! >>>>>>>>> >>>>>>>>> Cheeers, Timo >>>>>>>>> >>>>>>>> Thanks. I made an OCRed version using >>>>>>>> https://djvu.org/any2djvu, which seems to work fine. >>>>>>> >>>>>>> It wants a password, and my security software was wailing about >>>>>>> it. >>>>>>> >>>>>>> Joe >>>>>>> >>>>>> >>>>>> No password required when I use it. >>>>> >>>>> I just checked again, got the djvu password request. >>>>> >>>>> You may have your credentials cached, so it doesn't keep asking you. >>>>> >>>>> If you come in using a private browser window, what happens? >>>>> >>>>> Joe Gwinn >>>>> >>>> >>>> Weird. If I just type djvu.org into the address bar, it comes up in >>>> http:// and works normally. The https:// thing works as you say. >>>> >>>> Use the http:// one. ;0 >>> >>> Using plain http did get rid of the password dialog, and did get me to >>> the any2djvu page, which is not an OCRed copy of anything. >>> >>> Joe Gwinn >>> >> >> Try it out on an actual PDF. There are several options for getting >> embedded text, two of which involve OCR. I've done hundreds of >> documents that way, from one-pagers up to full-length books. It's Good >> Medicine. > > Ahh. I thought that an already OCRed pdf was there. I don't have the > original pdf yet. Where do I find that? > > Thanks, > > Joe Gwinn >Timo's link above. Cheers Phil Hobbs -- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC / Hobbs ElectroOptics Optics, Electro-optics, Photonics, Analog Electronics Briarcliff Manor NY 10510 http://electrooptical.net http://hobbs-eo.com
