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
Low noise, high bias voltage on picoAmp TIA's input, howto?
Started by ●May 21, 2021
Reply by ●May 27, 20212021-05-27
Reply by ●May 27, 20212021-05-27
On Thursday, May 27, 2021 at 8:04:12 AM UTC-7, Bill Sloman wrote:> > > whit3rd schrieb am Dienstag, 25. Mai 2021 um 21:08:34 UTC+2: > > > The drive (for a DC low-ripple output) would best be a triangle wave, so > > > the rectifiers after the transformer only make a short blip twice per cycle.> > The "blip" stimulates trr-ringing, at least in my case. > > Does triangle differ from sine significantly in this regard?> Probably not.The voltage output of a transformer is proportional to the d/dt of its primary current. Constant voltage output results from a triangle-wave input current, except at turnovers. So, the output-side rectified output only has a blip to cover with its filter capacitor, rather than the second harmonic of the drive frequency
Reply by ●May 27, 20212021-05-27
Bill Sloman 17:04 (vor 3 Stunden)> It should be just as good on a small core, unless you manage to saturate the core. > You could e-mail me the L-Spice simulation (to bill.sloman at ieee.org)- or post it here as the text version of the .asc file.I put the zip onto the little site (last position): https://ibtk.de/project/hzdr/Fameio-presentation/20210521_Fameio.html I got the symbol idea for the saturable transformer here: https://www.mikrocontroller.net/topic/373488#4226728 Thank you!
Reply by ●May 27, 20212021-05-27
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. (I already have a copy of the paper book, but it ain't searchable.) 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 27, 20212021-05-27
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
Reply by ●May 27, 20212021-05-27
Am 21.05.21 um 14:08 schrieb timo.k...@ibtk.de: Hi, Timo! since you are interested in measuring small currents, you might like this one: < https://sci-hub.do/10.1063/1.4997963 > They even T-compensated the FET bias current. I'm currently out of sync with the wall clock but happy since I repaired and calibrated my no longer booting HP 54750A sampling scope mainframe today. In the end, it was an empty Lithium battery on the CPU board. It was COMPLETELY empty, not a mV! With the new battery, it complained about missing cal-factors. I wonder how that thing worked the last years at all. Wow! 68020 with floating point coprocessor! Note to selfes: Don't try to remove the box/handles/bottom feet etc. Impossible or futile. Spot-welded, unlike the usual HP/Agilent boxes. Just remove the backplate. Cheers, Gerhard
Reply by ●May 28, 20212021-05-28
On Friday, May 28, 2021 at 4:08:10 AM UTC+10, whit3rd wrote:> On Thursday, May 27, 2021 at 8:04:12 AM UTC-7, Bill Sloman wrote: > > > > > whit3rd schrieb am Dienstag, 25. Mai 2021 um 21:08:34 UTC+2: > > > > The drive (for a DC low-ripple output) would best be a triangle wave, so > > > > the rectifiers after the transformer only make a short blip twice per cycle. > > > > The "blip" stimulates trr-ringing, at least in my case. > > > Does triangle differ from sine significantly in this regard? > > > Probably not. > The voltage output of a transformer is proportional to the d/dt of its primary > current. Constant voltage output results from a triangle-wave input current, > except at turnovers. > So, the output-side rectified output only has a blip to cover with > its filter capacitor, rather than the second harmonic of the drive frequency.Except that the blip is the current moving from one rectifier to another. The two alternative paths both have inductance, and the rectifiers have been known to act as step-recovery diodes, and that can generate some very high rates of change of current, and corresponding large voltage spikes. -- Bill Sloman, Sydney
Reply by ●May 28, 20212021-05-28
On Friday, May 28, 2021 at 4:43:10 AM UTC+10, timo.k...@ibtk.de wrote:> Bill Sloman > 17:04 (vor 3 Stunden) > > It should be just as good on a small core, unless you manage to saturate the core. > > You could e-mail me the L-Spice simulation (to bill.sloman at ieee.org)- or post it here as the text version of the .asc file. > I put the zip onto the little site (last position): > https://ibtk.de/project/hzdr/Fameio-presentation/20210521_Fameio.html > I got the symbol idea for the saturable transformer here: > https://www.mikrocontroller.net/topic/373488#4226728The zip file isn't easy to open as text, and LTSpice 4 threatens to dump most of the content. E-mail of an un-zipped file would be easier. I can read German - if not all that well - but my wife could help with any difficult bits. Bill Sloman, Sydney
Reply by ●May 28, 20212021-05-28
On Friday, May 28, 2021 at 1:42:57 PM UTC+10, Bill Sloman wrote:> On Friday, May 28, 2021 at 4:43:10 AM UTC+10, timo.k...@ibtk.de wrote: > > Bill Sloman > > 17:04 (vor 3 Stunden) > > > > > It should be just as good on a small core, unless you manage to saturate the core. > > > You could e-mail me the L-Spice simulation (to bill.sloman at ieee.org)- or post it here as the text version of the .asc file. > > I put the zip onto the little site (last position): > > https://ibtk.de/project/hzdr/Fameio-presentation/20210521_Fameio.html > > I got the symbol idea for the saturable transformer here: > > https://www.mikrocontroller.net/topic/373488#4226728 > The zip file isn't easy to open as text, and LTSpice 4 threatens to dump most of the content. E-mail of an un-zipped file would be easier. I can read German - if not all that well - but my wife could help with any difficult bits.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 .... -- Bill Sloman, Sydney
Reply by ●May 28, 20212021-05-28
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.asc 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 am still not sure which version would be the more suitable for that application. At least I saw the bipolar version working. ;) The Schottkys are a try only together with the BE-diodes. Delete them... Cheers, Timo Kirschke
