Tim Williams wrote:> "Robert Baer" <robertbaer@localnet.com> wrote in message > news:IpqdnflGK8W9KY3NnZ2dnUVZ_uWdnZ2d@posted.localnet... >> I need a 2-terminal device so tat i can put hundreds of them in series >> for 25KV. >> So far, only one person divined that and his comment was trounced, and >> not politely. > > Like I said before (though possibly not in this thread), cascode some HV > MOSFETs. Only way you'll get the stability and noise you demand, without > stacking a bajillion 431's. > > Tim >Stacking 431s does work, but that cannot be used for this app as the standby or keep-alive current is too high. And the other reference voltage parts cost too much (say 2.5V times 10,000 times price each).
Zener noise / oscillations
Started by ●July 23, 2012
Reply by ●July 27, 20122012-07-27
Reply by ●July 27, 20122012-07-27
Jan Panteltje wrote:> On a sunny day (Wed, 25 Jul 2012 20:06:05 -0700) it happened Robert Baer > <robertbaer@localnet.com> wrote in > <IpqdnflGK8W9KY3NnZ2dnUVZ_uWdnZ2d@posted.localnet>: > >> Jan Panteltje wrote: >>> On a sunny day (Tue, 24 Jul 2012 23:39:15 -0700) it happened Robert Baer >>> <robertbaer@localnet.com> wrote in >>> <WeudnYHn_bcLCZLNnZ2dnUVZ_jOdnZ2d@posted.localnet>: >>> >>>> Tim Williams wrote: >>>>> "Robert Baer"<robertbaer@localnet.com> wrote in message >>>>> news:y4CdnbWbSZcVtpPNnZ2dnUVZ_rGdnZ2d@posted.localnet... >>>>>> Yes, a TL431 is cheap but the minimal standing current is way above >>>>>> what is needed. >>>>> >>>>> 1mA? TLV431 is 100uA and 1.240V, much improved. >>>>> >>>>> Tim >>>>> >>>> Range needed: 10uA-500uA. >>> >>> It is interesting to note that the PIC 18F14K22 is specified with FVR only running at: >>> 1.8V 28 uA >>> 3V 65 uA >>> 5V 101 uA >>> For a reference output of 1.024V >>> >>> I would think that if you put it into sleep mode, that would make your specs... >>> Datasheet page 337 >>> It is possible to send the Vref output to a pin in that mode AFAIK. >> I need a 2-terminal device so tat i can put hundreds of them in >> series for 25KV. >> So far, only one person divined that and his comment was trounced, >> and not politely. > > OK, so I did not see you mention 25kV @ say<100uA. > That will not be easy with zeners.* Tell me about it; seems almost all have a negative R region right where i need to operate.> > You also need to mention stabilisation factor in percent for example, > for anybody to even think about it.* What exactly do you mean by stabilization? See below.> > I could easily generate 25kV locally with a transistor circuit and > even some feedback turns, without a bleeder on the whole HV. > Any decent last century CRT solid state color TV does it that way. > Zeners do not make that much sense here to me.* This is a TV restoration project; ideally the looks are preserved. *** Have done some suggested testing of the 75V part and compared the result to the same testing of the 68V part. What i find interesting is that for negative resistance parts, the (what i call) the "N" type where voltage goes down as current increases (eg: Esaki or tunnel diode), it is very easy to get to oscillate; for the (what i call) the "S" type where current goes down as voltage increases (eg: Zeners with "switchback"), it is hard to make it oscillate. The 75V part looks good, now i will chain some together..
Reply by ●July 27, 20122012-07-27
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..
Reply by ●July 27, 20122012-07-27
Jan Panteltje wrote:> On a sunny day (Thu, 26 Jul 2012 07:49:00 -0500) it happened "Tim Williams" > <tmoranwms@charter.net> wrote in<jurec9$hke$1@dont-email.me>: > >> Ah, so suppose I were to order 10000 uCs from Digikey, preprogrammed. HOw >> shall I tell them they each need a unique #define? >> >> Tim > > > Thats is silly, for normal applications the reference is accurate enough, > only for super precise things and test equipment where calibration is needed > would you use the #define method. > And I could even automate that, see how? > Same goes for internal oscillator settings, it [some PIC} has a factory adjusted byte > that presets it to +-1%, but you can, in your production test, easily > include an auto-calibration against some super accurate source you have. > If you do not test you products at all yes then you make X % crap anyways. > Was not that saying: > Those who say it cannot be done should not interrupt person doing it? > >Most especially do NOT disturb someone doing the "impossible"!
Reply by ●July 27, 20122012-07-27
Fred Abse wrote:> On Wed, 25 Jul 2012 20:50:26 -0700, Robert Baer wrote: > >> I have posted a 7CT1N curve tracer screen photo under the heading >> "ref:Zener noise / oscillations". > > Which 7000 series mainframe has a *red* phosphor? >Not red, is yellow; digital camera and color inversion does the rest (note BLUE graticule).
Reply by ●July 27, 20122012-07-27
Fred Abse wrote:> On Thu, 26 Jul 2012 13:02:58 -0700, Fred Abse wrote: > >> On Wed, 25 Jul 2012 20:50:26 -0700, Robert Baer wrote: >> >>> I have posted a 7CT1N curve tracer screen photo under the heading >>> "ref:Zener noise / oscillations". >> >> Which 7000 series mainframe has a *red* phosphor? > > I forgot to ask: > > What zener? > > What voltage and current scales? > > What series resistance? > > I'd like to try that. >Worst one seen: Vishay MMBZ5266C-V-GS08, 68V SOT-23; expect their DO-35 to be exactly the same (one datasheet covers all of them). 20V/div and 50uA/div using the 7CT1N curve tracer; no series resistance selectable.
Reply by ●July 27, 20122012-07-27
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 (Thu, 26 Jul 2012 22:29:12 -0700) it happened Robert Baer <robertbaer@localnet.com> wrote in <pZGdnYMvoYe2uo_NnZ2dnUVZ_qqdnZ2d@posted.localnet>:>Jan Panteltje wrote: >> On a sunny day (Thu, 26 Jul 2012 07:49:00 -0500) it happened "Tim Williams" >> <tmoranwms@charter.net> wrote in<jurec9$hke$1@dont-email.me>: >> >>> Ah, so suppose I were to order 10000 uCs from Digikey, preprogrammed. HOw >>> shall I tell them they each need a unique #define? >>> >>> Tim >> >> >> Thats is silly, for normal applications the reference is accurate enough, >> only for super precise things and test equipment where calibration is needed >> would you use the #define method. >> And I could even automate that, see how? >> Same goes for internal oscillator settings, it [some PIC} has a factory adjusted byte >> that presets it to +-1%, but you can, in your production test, easily >> include an auto-calibration against some super accurate source you have. >> If you do not test you products at all yes then you make X % crap anyways. >> Was not that saying: >> Those who say it cannot be done should not interrupt person doing it? >> >> > Most especially do NOT disturb someone doing the "impossible"!Impossible is a very flexible thing. http://www.youtube.com/watch?v=JRPC7a_AcQo I hope you have high banddwidth by now, video is very interesting, not so much electronics, but more physics.
Reply by ●July 27, 20122012-07-27
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...
Reply by ●July 27, 20122012-07-27
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.
