On a sunny day (Fri, 27 Jul 2012 02:45:40 -0400) it happened "Michael A. Terrell" <mike.terrell@earthlink.net> wrote in <lOednelhLL2KpI_NnZ2dnUVZ_rOdnZ2d@earthlink.com>:> >Jan Panteltje wrote: >> >> On a sunny day (Thu, 26 Jul 2012 22:25:12 -0700) it happened Robert Baer >> <robertbaer@localnet.com> wrote in >> <pZGdnYEvoYehu4_NnZ2dnUVZ_qqdnZ2d@posted.localnet>: >> >> >* This is a TV restoration project; ideally the looks are preserved. >> >> In color TV, and your 25 kV points to that, >> the beam current can vary between 0 and about 1.5 mA (maybe more). >> Stabilization of the HV (that comes from the horizontal output transformer) via a voltage multiplier, >> is normally done by looking at a lower voltage pulse from that output transformer. >> Its amplitude will decrease a lot with increasing beam current, so you can use it >> in a control loop. >> >> In the old tube days a parallel stabilizer triode was used and a single phase tube rectifier. >> >> But never ever in my life have I seen zeners over the 25 kV, that would be problematic >> as the power consumption is huge, if you send 1.5 mA at 25 kV into your zeners for a 'black' >> screen, than those zeners will dissipate 37.5 W. >> In reality more, as you have to pre-load those zeners. >> I recommend the voltage multiplier and feedback winding method... > > > Or stock up on HV regulator tubes. They are still widely availibe >and cheap, since there is little demand for them.Yes, but then he has to put them in a clsed metal cage agaisnt roentgen radiation.
Zener noise / oscillations
Started by ●July 23, 2012
Reply by ●July 27, 20122012-07-27
Reply by ●July 27, 20122012-07-27
On 27.7.12 10:26 , Jan Panteltje wrote:> On a sunny day (Fri, 27 Jul 2012 02:45:40 -0400) it happened "Michael A. > Terrell" <mike.terrell@earthlink.net> wrote in > <lOednelhLL2KpI_NnZ2dnUVZ_rOdnZ2d@earthlink.com>: > >> >> Jan Panteltje wrote: >>> >>> On a sunny day (Thu, 26 Jul 2012 22:25:12 -0700) it happened Robert Baer >>> <robertbaer@localnet.com> wrote in >>> <pZGdnYEvoYehu4_NnZ2dnUVZ_qqdnZ2d@posted.localnet>: >>> >>>> * This is a TV restoration project; ideally the looks are preserved. >>> >>> In color TV, and your 25 kV points to that, >>> the beam current can vary between 0 and about 1.5 mA (maybe more). >>> Stabilization of the HV (that comes from the horizontal output transformer) via a voltage multiplier, >>> is normally done by looking at a lower voltage pulse from that output transformer. >>> Its amplitude will decrease a lot with increasing beam current, so you can use it >>> in a control loop. >>> >>> In the old tube days a parallel stabilizer triode was used and a single phase tube rectifier. >>> >>> But never ever in my life have I seen zeners over the 25 kV, that would be problematic >>> as the power consumption is huge, if you send 1.5 mA at 25 kV into your zeners for a 'black' >>> screen, than those zeners will dissipate 37.5 W. >>> In reality more, as you have to pre-load those zeners. >>> I recommend the voltage multiplier and feedback winding method... >> >> >> Or stock up on HV regulator tubes. They are still widely availibe >> and cheap, since there is little demand for them. > > Yes, but then he has to put them in a clsed metal cage agaisnt roentgen radiation.There should be a shield already - the same X-ray (Roentgen) radiation hazard consideration applies to the plasma regulator tubes. -- Tauno Voipio
Reply by ●July 27, 20122012-07-27
So......in other words, you concede? Note: trimpots and THT may work in China but Made in USA (or Europe for that matter) products can only tolerate a minimum of labor. This is a real market and there are real products doing exactly what I describe. But they don't use crappy onboard uC references to do it, they use one with guaranteed specs. Tim -- Deep Friar: a very philosophical monk. Website: http://webpages.charter.net/dawill/tmoranwms "Jan Panteltje" <pNaonStpealmtje@yahoo.com> wrote in message news:jut9ig$pgd$1@news.albasani.net...> On a sunny day (Thu, 26 Jul 2012 17:45:17 -0500) it happened "Tim > Williams" > <tmoranwms@charter.net> wrote in <jushab$b90$1@dont-email.me>: > >>Ok then. >> >>Provide an example wherein a PIC is used, alone, with no external >>reference, >>as a voltmeter with guaranteed 0.1% accuracy. The design must be >>DFM-ready, >>meaning, it must use a single code version, so that all components can be >>purchased en masse, assembled by a contract assembler, and shipped direct >>to >>customers. No measurement step, no calibration step, no reprogramming >>allowed (other than what it can do internally, which won't be too useful). > > I worked for Tek, did some calibration and also QC. > In calibration you get a book with steps to check and adjust, work through > it, are not allowed to make any notes, > and make everything in spec. > In the next step, the QC, an OTHER person does the same, but adjusts > nothing, just give it back if it is not in spec. > You have a bench of very high quality equipment (rack full, all Tek too), > as calibration tools. > If the calibrator cannot get it in spec he may give it back to the factory > floor or perhaps check and repair if he can. > That is what makes a Tek so expensive. > And that is where precision is achieved. > The references and trimpots are just 10 cent little things you can get > from anywhere, used to surprise me in the > beginning, not 10 turns, no nothing like that. Bending of wires to the CRT > to get 'in spec' on the bandwidth was normal too. > So before you start on your jive of manufacturing 'precision' equipment, > better look on how that is done. > > In any other case your design sucks if it needs 1 in a thousand for every > day stuff. > So that is MY view and MY experience. > > BTW the 3 $ multimeters from China I have, and I love those, have a > similar trimpot in them. > It is a MASS MASS MASS MANY MANY product, and I suspect a little Chinese > girl twiddling at 1000 an hour on a test bench where they fly past her, > The trimpots are so feeble and flexible mounted that I cannot imagine a > robot hitting the slot in it. > But I could imagine this person having a controlled screwdriver from some > test point on the PCB setting the pot to the right value. > Only limited by your imagination. > > Thank you for reading > > WTF am I writing this at 7:30 in the morning? > :-)
Reply by ●July 27, 20122012-07-27
On a sunny day (Fri, 27 Jul 2012 07:53:54 -0500) it happened "Tim Williams" <tmoranwms@charter.net> wrote in <juu31i$2a8$1@dont-email.me>:>So......in other words, you concede?No. Read again what I wrote.>Note: trimpots and THT may work in China but Made in USA (or Europe for that >matter) products can only tolerate a minimum of labor. This is a real >market and there are real products doing exactly what I describe. But they >don't use crappy onboard uC references to do it, they use one with >guaranteed specs.PIC internal reference is not crappy at all. A lot better than the zeners you use in your voltage converter diagrams :-) Fight fight fight... :-)>Tim > >-- >Deep Friar: a very philosophical monk. >Website: http://webpages.charter.net/dawill/tmoranwms > >"Jan Panteltje" <pNaonStpealmtje@yahoo.com> wrote in message >news:jut9ig$pgd$1@news.albasani.net... >> On a sunny day (Thu, 26 Jul 2012 17:45:17 -0500) it happened "Tim >> Williams" >> <tmoranwms@charter.net> wrote in <jushab$b90$1@dont-email.me>: >> >>>Ok then. >>> >>>Provide an example wherein a PIC is used, alone, with no external >>>reference, >>>as a voltmeter with guaranteed 0.1% accuracy. The design must be >>>DFM-ready, >>>meaning, it must use a single code version, so that all components can be >>>purchased en masse, assembled by a contract assembler, and shipped direct >>>to >>>customers. No measurement step, no calibration step, no reprogramming >>>allowed (other than what it can do internally, which won't be too useful). >> >> I worked for Tek, did some calibration and also QC. >> In calibration you get a book with steps to check and adjust, work through >> it, are not allowed to make any notes, >> and make everything in spec. >> In the next step, the QC, an OTHER person does the same, but adjusts >> nothing, just give it back if it is not in spec. >> You have a bench of very high quality equipment (rack full, all Tek too), >> as calibration tools. >> If the calibrator cannot get it in spec he may give it back to the factory >> floor or perhaps check and repair if he can. >> That is what makes a Tek so expensive. >> And that is where precision is achieved. >> The references and trimpots are just 10 cent little things you can get >> from anywhere, used to surprise me in the >> beginning, not 10 turns, no nothing like that. Bending of wires to the CRT >> to get 'in spec' on the bandwidth was normal too. >> So before you start on your jive of manufacturing 'precision' equipment, >> better look on how that is done. >> >> In any other case your design sucks if it needs 1 in a thousand for every >> day stuff. >> So that is MY view and MY experience. >> >> BTW the 3 $ multimeters from China I have, and I love those, have a >> similar trimpot in them. >> It is a MASS MASS MASS MANY MANY product, and I suspect a little Chinese >> girl twiddling at 1000 an hour on a test bench where they fly past her, >> The trimpots are so feeble and flexible mounted that I cannot imagine a >> robot hitting the slot in it. >> But I could imagine this person having a controlled screwdriver from some >> test point on the PCB setting the pot to the right value. >> Only limited by your imagination. >> >> Thank you for reading >> >> WTF am I writing this at 7:30 in the morning? >> :-) > >
Reply by ●July 27, 20122012-07-27
Jan Panteltje wrote:> > On a sunny day (Fri, 27 Jul 2012 02:45:40 -0400) it happened "Michael A. > Terrell" <mike.terrell@earthlink.net> wrote in > <lOednelhLL2KpI_NnZ2dnUVZ_rOdnZ2d@earthlink.com>: > > > > >Jan Panteltje wrote: > >> > >> On a sunny day (Thu, 26 Jul 2012 22:25:12 -0700) it happened Robert Baer > >> <robertbaer@localnet.com> wrote in > >> <pZGdnYEvoYehu4_NnZ2dnUVZ_qqdnZ2d@posted.localnet>: > >> > >> >* This is a TV restoration project; ideally the looks are preserved. > >> > >> In color TV, and your 25 kV points to that, > >> the beam current can vary between 0 and about 1.5 mA (maybe more). > >> Stabilization of the HV (that comes from the horizontal output transformer) via a voltage multiplier, > >> is normally done by looking at a lower voltage pulse from that output transformer. > >> Its amplitude will decrease a lot with increasing beam current, so you can use it > >> in a control loop. > >> > >> In the old tube days a parallel stabilizer triode was used and a single phase tube rectifier. > >> > >> But never ever in my life have I seen zeners over the 25 kV, that would be problematic > >> as the power consumption is huge, if you send 1.5 mA at 25 kV into your zeners for a 'black' > >> screen, than those zeners will dissipate 37.5 W. > >> In reality more, as you have to pre-load those zeners. > >> I recommend the voltage multiplier and feedback winding method... > > > > > > Or stock up on HV regulator tubes. They are still widely availibe > >and cheap, since there is little demand for them. > > Yes, but then he has to put them in a clsed metal cage agaisnt roentgen radiation.No, you don't. There are some types with enough lead to stop the radiation. At least in the US.
Reply by ●July 27, 20122012-07-27
"Jan Panteltje" <pNaonStpealmtje@yahoo.com> wrote in message news:juu43l$fh0$1@news.albasani.net...> PIC internal reference is not crappy at all. > A lot better than the zeners you use in your voltage converter diagrams > :-)Zeners in my converters? Which ones? I only use zeners for clamping and stabilization, never as a reference. Even so, the lowly 1N5231B is rated for 2%, which is still better than your PIC. Are we done yet? If you're referring to TL431, do read the datasheet some time: its recommended symbol may be a controlled zener, but it's actually a high-gain op-amp with +in internally connected to 2.50V at 2% or better tolerance. And it has to be used as such. Hence the compensation stuff around it. I typically buy the -B versions, which are 0.5%. Anything better than that and I get a proper reference (< 0.1%, maybe by AD or LT). No need for a tedious adjustment step anywhere, domestic or in China. Tim -- Deep Friar: a very philosophical monk. Website: http://webpages.charter.net/dawill/tmoranwms
Reply by ●July 27, 20122012-07-27
"Robert Baer" <robertbaer@localnet.com> wrote in message news:pZGdnYAvoYcvu4_NnZ2dnUVZ_qqdnZ2d@posted.localnet...> Tim Williams wrote: >> Ah, so suppose I were to order 10000 uCs from Digikey, preprogrammed. >> HOw shall I tell them they each need a unique #define? >> >> Tim >> > Make a dedicated ATE that makes the measurement and does the > programming..using the same PIC, making it incestuous..Ah, but is it the same type chip (thus calibrating it to *a* standard, which may've been calibrated independently to within drift error), or is it the *same chip being placed on the board* (effectively a Rube Goldberg BIST), in which case yes, its calibration will check out as 0.1% or so, but not to an absolute standard? Self-modifying code is one thing, but self-modifying boards? The mind reels, LOL. :) Tim -- Deep Friar: a very philosophical monk. Website: http://webpages.charter.net/dawill/tmoranwms
Reply by ●July 27, 20122012-07-27
"Michael A. Terrell" <mike.terrell@earthlink.net> wrote in message news:lOednelhLL2KpI_NnZ2dnUVZ_rOdnZ2d@earthlink.com...> Or stock up on HV regulator tubes. They are still widely availibe > and cheap, since there is little demand for them.In the Olden Days, they had corotrons, which used some gas mix and multiple stages, or field emission or something, to do the same job as a zener or gas reg tube, but higher. Which is what's being replaced here. I guess the restoration sets in question were equipped with corotrons, which are a lot harder to come by than the triodes (e.g., 6BK4C for HV shunt reg, or 6HS5 et al. for pulse regulation), and converting them is out of the question for whatever reasons (e.g., it's not a reasonable facsimile of the original design, or it would require extensive modification). The desired solution is a "black box" can, which sits in the same space and does the same job. So, a shunt triode isn't a bad idea -- it's what the manufacturers originally did anyway. But that may not be an acceptable solution for very picky restorations. What was wrong with the MOSFET cascode? Put a TL/V431 at the bottom, maybe feed in a few extra mA from a lower voltage rail, and you're done. You could also cascode a TL/V431 with a higher voltage transistor (or a 6C4) with a 6BK4C, to get extremely well regulated HV in nearly a single stage. Tim -- Deep Friar: a very philosophical monk. Website: http://webpages.charter.net/dawill/tmoranwms
Reply by ●July 27, 20122012-07-27
Tim Williams wrote:> > "Michael A. Terrell" <mike.terrell@earthlink.net> wrote in message > news:lOednelhLL2KpI_NnZ2dnUVZ_rOdnZ2d@earthlink.com... > > Or stock up on HV regulator tubes. They are still widely availibe > > and cheap, since there is little demand for them. > > In the Olden Days, they had corotrons, which used some gas mix and multiple > stages, or field emission or something, to do the same job as a zener or gas > reg tube, but higher. Which is what's being replaced here. > > I guess the restoration sets in question were equipped with corotrons, which > are a lot harder to come by than the triodes (e.g., 6BK4C for HV shunt reg, > or 6HS5 et al. for pulse regulation), and converting them is out of the > question for whatever reasons (e.g., it's not a reasonable facsimile of the > original design, or it would require extensive modification). The desired > solution is a "black box" can, which sits in the same space and does the > same job. > > So, a shunt triode isn't a bad idea -- it's what the manufacturers > originally did anyway. But that may not be an acceptable solution for very > picky restorations. > > What was wrong with the MOSFET cascode? Put a TL/V431 at the bottom, maybe > feed in a few extra mA from a lower voltage rail, and you're done. > > You could also cascode a TL/V431 with a higher voltage transistor (or a 6C4) > with a 6BK4C, to get extremely well regulated HV in nearly a single stage.You can also trim the drive to the Horizontal Output tube.
Reply by ●July 28, 20122012-07-28
Tim Williams wrote:> "Michael A. Terrell" <mike.terrell@earthlink.net> wrote in message > news:lOednelhLL2KpI_NnZ2dnUVZ_rOdnZ2d@earthlink.com... >> Or stock up on HV regulator tubes. They are still widely availibe >> and cheap, since there is little demand for them. > > In the Olden Days, they had corotrons, which used some gas mix and > multiple stages, or field emission or something, to do the same job as a > zener or gas reg tube, but higher. Which is what's being replaced here. > > I guess the restoration sets in question were equipped with corotrons, > which are a lot harder to come by than the triodes (e.g., 6BK4C for HV > shunt reg, or 6HS5 et al. for pulse regulation), and converting them is > out of the question for whatever reasons (e.g., it's not a reasonable > facsimile of the original design, or it would require extensive > modification). The desired solution is a "black box" can, which sits in > the same space and does the same job. > > So, a shunt triode isn't a bad idea -- it's what the manufacturers > originally did anyway. But that may not be an acceptable solution for > very picky restorations. > > What was wrong with the MOSFET cascode? Put a TL/V431 at the bottom, > maybe feed in a few extra mA from a lower voltage rail, and you're done.* In other words, a modified version of my original Codatron(TM) (prelim pat app on my website).> > You could also cascode a TL/V431 with a higher voltage transistor (or a > 6C4) with a 6BK4C, to get extremely well regulated HV in nearly a single > stage. > > Tim >Check; these 25KV Corotron(TM) tubes are about 1.5" dia and 6" long. "Converting" them does not take extensive modification; remove bottom so zener stack can be inserted, the positive lead feeding thru a hole drilled in the connector pin on the top; looks preserved. The dicey part is the insulation between the stack and the inside metal shell..
