Zener noise / oscillations

current,

think the standard topology of high impedance source charging the parallel combination of zener || C should bring it out. There you would monitor zener current. Worth trying; thanks.

On a sunny day (Tue, 24 Jul 2012 23:39:15 -0700) it happened Robert Baer wrote in :

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.

Google groups still has it. Searching on "Zener diode oscillation" in google groups advanced search found it immediately. 96 posts, last post July 20, 1997.

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Bill Sloman, Nijmegen

On 24/07/12 09.39, Jan Panteltje wrote: ...

Please note it is spelled:

MCP1525

Glenn

On a sunny day (Wed, 25 Jul 2012 16:52:43 +0200) it happened Glenn wrote in :

Ooops :-)

LT1004-1.2 .. about 20 cents.

Or if you want to be a cheapskate and live without guarantees, using green LEDs as references has been discussed here a few times. With a one-Vbe drop (eg. follower) the tempco typically isn't nearly as bad as it could be.

Best regards, Spehro Pefhany

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7% accuracy too!

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running at:

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.

Thanks! Noticed the (first?) posting by Mike 7/20/97 where he was rather adamant about "No one can produce a sample of a zener that oscillates." and (to me) rather flippantly states "The person who first demonstrated the existence of oscillations in zeners would be up for the Nobel prize."

I must state "hogwash", in all that one needs for an oscillator is a device that exhibits negative resistance (note he _does_ mention Dr. Leo Esaki immediately afterwards). eXplicitly to the point, buy some Vishay MMBZ5266C-V-GS08 68V SOT-23 zeners and put them on a curve tracer; very nice negR jump in the

40-60uA region where the voltage DECREASES as the current INCREASES. I think the same die is available in the DO-35 package by Vishay if you need better power dissipation for your oscillator.

I have posted a 7CT1N curve tracer screen photo under the heading "ref:Zener noise / oscillations". Mike can send me a cash equivalent of the Nobel Prize any day now; i will be glad to share it with all those here that know better (ie: beans from duck-eggs).

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

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On a sunny day (Wed, 25 Jul 2012 20:06:05 -0700) it happened Robert Baer wrote in :

running at:

specs...

OK, so I did not see you mention 25kV @ say

On a sunny day (Thu, 26 Jul 2012 12:01:13 +1000) it happened "David Eather" wrote in :

Absolute accuracy as to 1.024 perhaps? I have used that reference in at least 3 projects now, also very long term, and also in temp stabilised (in the tritium decay experiment it is constantly compared against an other external reference), data shows it is still within 1 part in

1000 after more than 70 days (sampled each hour), Absolute accuracy is often not that important, as it can be calculated out, simply a #define in the software.

Ah, so suppose I were to order 10000 uCs from Digikey, preprogrammed. HOw shall I tell them they each need a unique #define?

Tim

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Tim Williams a écrit :

Nah, have it programmed with a C compiler and small bootstrap that calibrate the #define generate the source, compile the program and then flash it :-)

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Thanks,
Fred.

On a sunny day (Thu, 26 Jul 2012 07:49:00 -0500) it happened "Tim Williams" wrote in :

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?

Which 7000 series mainframe has a *red* phosphor?

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I forgot to ask:

What zener?

What voltage and current scales?

What series resistance?

I'd like to try that.

--
"For a successful technology, reality must take precedence 
over public relations, for nature cannot be fooled."
                                       (Richard Feynman)

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).

If the internal reference has the stated accuracy (~0.1%, i.e., "1.024"), this should be trivial. If not, then don't call it what it clearly is not. This goes double for the manufacturer, to whom less attention should be paid as a result.

Note that "1.024" at 7% is 0.952 to 1.096. It's closer to "1.0", which implies 10% error, than it is to "1.02", which implies 1%.

Tim

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