2N2222 Zener noise

voltage?

diode is in series with > the zener stabilizes the effects between the two.

No, it means the both of you are confused. Don't count your chickens boy, before they hatch..

P.S. Yes, you need all the help you can get, so fitting for him to join in. Good luck with that one.

voltage?

Good noise approximates a physical, random process. Different defects matter to different people. The RF boys want spectral flatness. Crypto people want zero predictability. Process people might want a nearly Gaussian PD. Audio folks don't want audible defects, like hum or popcorn noise or detected RF.

Look it up.

John

On a sunny day (Sat, 27 Nov 2010 13:28:33 -0800) it happened John Larkin wrote in :

I assume you mean a few volt?

what constitutes high quality noise? I've never heard it put that way! :)

Noise is noise, be it white, pink, brown and your analogy "Popcorn", first time I've heard that one ect !

Am 27.11.2010 20:17, schrieb John Larkin: o $0.61 each, which is pretty close to a "sand power"

Probably data shhet spec. Bringing BE to breakdown ruins the low noise property of a transistor. For example, in the Infineon npn BC847-850 and pnp BC857-860 series, the BC850 / 860 subtypes are guaranteed for noise and promptly have reduced Vbe specs IIRC. I assume the whole familly is made on the same process, maybe same wafers.

Most of my customers would blacklist you for admitting that.

Gerhard

I don't have my data here, but I recall a BCX70 running around 8 volts Vbe zener voltage, and changing maybe a tenth of a volt over a few days.

Gathering some better data, including beta degradation, would be an ideal project for some unemployed PhD.

John

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voltage?

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diode is in series with > the zener stabilizes the effects between the two.

Did you even READ the link I posted? That Harvard prof says you're full of shit, too. ...but of course you know more than everyone.

To tell any newbs here that you're chronically full of shit, sure. I'm more than happy to help.

The schottky in question is intended for RF detector use, so there's no reason the vendor should spec them past -2. They probably don't even test for it.

To get really high performance, especially speed, you have to stress parts. The trick is to test them carefully and back off some prudent amount. Schottkies, fortunately, just leak more as voltage goes up, and if there's not a lot of current available, there's probably no long-term degradation mechanism. No problems so far.

Lots of parts, especially RF stuff, are simply missing key specs, so all you can do is test.

Sloppy design within ratings probably kills more circuits than the occasional, thoughtfully considered spec push. Lots of tantalum caps, for example, have exploded into flames while operating well within their specs.

John

voltage?

That's interesting, I did look that up, and it appears to be another name of something I was already aware of.. I read a parcel on Wki and it mention behavior of defects found in transistors.

I did have a batch of smt 2222's that would not work in linear applications, only switching because at a specific current (Ice) No mater the configuration, I was getting a small noise that could be seen via scope in the collector circuit. You go below or above this current point and it would go away.. When I set the scope up to expand the view on that section, I go what looked like a random oscillation.

I used a spectrum analyzer on that point and got random noise that started around 100hz up to about 1 mhz.. It would change just by varying the bias slightly.

I have since replaced that batch and all is well once again.

MMBT2222 iirc...

Popcorn noise is short bursts of very loud noise caused by contamination with heavy metal ions. Much like the sound of popcorn in statu nascendi. In the 1974 RCA intgegrated circuits data book there was an app note on how to measure it.

PCN is no problem in products from better manufacturers nowadays.

regards, Gerhard

Gerhard, sometimes the envelope needs to be pushed. I doubt the Space Shuttle would have ever flown if they would not have done that. Yeah, it does carry a risk. But as they say, no risk, no reward. The risk can be minimized. For example, in the case of a Schottky used past limits you make sure no excess current can flow and, if needed, there are redundant system so the mission can be completed.

Very popular: Frequency range 100MHz to xGHz. Upon contacting the mfgs it often turns out that they simply did not measure below 100MHz so they had no data. So they cut the spec there but it runs all the way down to DC.

Oh yeah. I remember the words of a production tech: "There was a loud bang, and then it was like popcorn".

voltage?

Popcorn noise is super low frequency and is usually seen in the form of discrete/bimodal level shifts, like the output of a random pulse generator. It's common for it to look like pulses, milliseconds in duration, milliseconds to seconds apart, or random in time level shifts. Sometimes a part will sit quietly for hours and then let out a burst. The magnitude is in the ballpark of 10s of microvolts RTI. The cause is supposedly ionic contamination in oxide layers or something. It's named because it sounds like corn popping.

Analog Devices has an appnote where they claim it's a thing of the past. They should test some of their own DACs.

John

That would be called a silicon fart :-)

You mean like the claim a long time ago that the recession is over? Or that increasing public employee pensions by 50% will have no noticeable effect on the asset levels of pension funds?

Am 28.11.2010 00:07, schrieb John Larkin:

OK, but the wording then has to be like "We took the burden to re-characterize the part in this non-standard environment" and not "the mfg says -2, but -6 seems to work" :-)

(my 1st language is not English)

For NEC and other reputable mfgs the spec says 1/3 Ohm per Volt source resistance, and then they won't explode.

Gerhard

Am 28.11.2010 00:44, schrieb Joerg:

Can't you keep this political liqui-shit out of sci.electronics.design? This group could be really interesting, but that 95% of "left-wing" vs "AmeriNazi" content makes it just useless.

Gerhard

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So you are not only stupid, but also young.

Not only the 709 but also the 741 suffered from thos problem

RCA even went to the trouble of making a version of the 741 with a popcorn noise specification.

I've been assured that modern 741's don't have this problem, but around 1988 I appreciably improved the performance of the Cambridge Instruments/ Metals Research Gallium Arsenide Crystal Puller by replacing one uA741 with an OP-07, which does happen to have a popocorn noise specification.

I did quite a bit more to the machine's electronics, but the absence of popcorn noise made a very perceptible difference to the way the machine performed, and probably reduced the residual thermal stresses in the single-crystal GaAs that the machine produced (roughly 95% of the single cyrstal GasAs produced in the west at the time).

-- Bill Sloman, Nijmegen

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You would.

I'm quoting the data-sheet specification. I'm well aware that even a little reverse break-down of a base-emitter junction can degrade the forward current gain of a transistor, and I've heard the story about the HP technicians who used to "repair" metal-cased output transistors by stubbing their cigarettes out on the device - it provided just enough thermal annealing to get rid of the worst of the damage.

I never had the occasion to destroy a broad-band transistor by finding out it's actual reverse breakdown voltage.

-- Bill Sloman, Nijmegen

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If he had the gear and the transistors. Electronics is an expensive hobby.

-- Bill Sloman, Nijmegen

Then take a sledge hammer to your computer, before you kill yourself over it.