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Exhausted

Started by David Eather March 16, 2016
If any kind soul can help...

There was a short post/note on SED or SEB about a transistor with a 2.5V  
max Vebo and another one with 3.0 max Vebo. I have spent hours looking for  
the transistors and have run out of options. Does anyone remember which  
transistor numbers these were?

I'm adding transistor junction breakdown noise to a Arduino and they would  
fit the bill perfectly - and cut out problem of providing extra voltage  
sources other than %v power from USB.

As always TIA.
On Wednesday, March 16, 2016 at 6:53:11 AM UTC+1, David Eather wrote:
> If any kind soul can help... > > There was a short post/note on SED or SEB about a transistor with a 2.5V > max Vebo and another one with 3.0 max Vebo. I have spent hours looking for > the transistors and have run out of options. Does anyone remember which > transistor numbers these were? > > I'm adding transistor junction breakdown noise to a Arduino and they would > fit the bill perfectly - and cut out problem of providing extra voltage > sources other than %v power from USB. > > As always TIA.
This one: https://groups.google.com/forum/#!searchin/sci.electronics.design/vebo$203$202.5/sci.electronics.design/_CltveiGmEY/3YcRcP_4QUwJ
On Wednesday, March 16, 2016 at 1:53:11 AM UTC-4, David Eather wrote:
> If any kind soul can help... > > There was a short post/note on SED or SEB about a transistor with a 2.5V > max Vebo and another one with 3.0 max Vebo. I have spent hours looking for > the transistors and have run out of options. Does anyone remember which > transistor numbers these were? > > I'm adding transistor junction breakdown noise to a Arduino and they would > fit the bill perfectly - and cut out problem of providing extra voltage > sources other than %v power from USB. > > As always TIA.
I don't know the transistors, but have you tried a low voltage zener. (The problem with both is that you may not get much more than just the shot noise.) George H.
On Wed, 16 Mar 2016 23:04:13 +1000, George Herold <gherold@teachspin.com>  
wrote:

> On Wednesday, March 16, 2016 at 1:53:11 AM UTC-4, David Eather wrote: >> If any kind soul can help... >> >> There was a short post/note on SED or SEB about a transistor with a 2.5V >> max Vebo and another one with 3.0 max Vebo. I have spent hours looking >> for >> the transistors and have run out of options. Does anyone remember which >> transistor numbers these were? >> >> I'm adding transistor junction breakdown noise to a Arduino and they >> would >> fit the bill perfectly - and cut out problem of providing extra voltage >> sources other than %v power from USB. >> >> As always TIA. > > I don't know the transistors, but have you tried a low voltage zener. > (The problem with both is that you may not get much more than just the > shot noise.) > > George H.
Zener is OK but my experiments suggest noise is about an order of magnitude lower. On the plus side transistor junctions seem to 'age' and become quieter as time goes on. (both effects may be non-existent and just the result of my poor experiments)
George Herold wrote...
> >On Wednesday, March 16, 2016 at 1:53:11 AM UTC-4, David Eather wrote: >> If any kind soul can help... >> >> There was a short post/note on SED or SEB about a transistor with a 2.5V >> max Vebo and another one with 3.0 max Vebo. I have spent hours looking for >> the transistors and have run out of options. Does anyone remember which >> transistor numbers these were? >> >> I'm adding transistor junction breakdown noise to a Arduino and they would >> fit the bill perfectly - and cut out problem of providing extra voltage >> sources other than %v power from USB. >> >> As always TIA. > > I don't know the transistors, but have you tried a low voltage zener. > (The problem with both is that you may not get much more than just the > shot noise.)
Agreed, the zener noise mechanism comes from avalanche, which doesn't kick in until you get to voltages above about 8 volts. Low-current "microplasmas" form and quickly terminate after discharging the zener's self capacitance, creating a kind of popcorn noise. There are extensive threads on the subject 15-20 years ago on s.e.d., where I spent a month (haha, more) making and posting all kinds of nanosecond-scale measurements. The zener physics effect (field emission) predominates at low-voltages, see the ON Semi handbook, HBD854, page 20. https://www.onsemi.com/pub/Collateral/HBD854-D.PDF -- Thanks, - Win
On Wednesday, March 16, 2016 at 10:33:03 AM UTC-4, Winfield Hill wrote:
> George Herold wrote... > > > >On Wednesday, March 16, 2016 at 1:53:11 AM UTC-4, David Eather wrote: > >> If any kind soul can help... > >> > >> There was a short post/note on SED or SEB about a transistor with a 2.5V > >> max Vebo and another one with 3.0 max Vebo. I have spent hours looking for > >> the transistors and have run out of options. Does anyone remember which > >> transistor numbers these were? > >> > >> I'm adding transistor junction breakdown noise to a Arduino and they would > >> fit the bill perfectly - and cut out problem of providing extra voltage > >> sources other than %v power from USB. > >> > >> As always TIA. > > > > I don't know the transistors, but have you tried a low voltage zener. > > (The problem with both is that you may not get much more than just the > > shot noise.) > > Agreed, the zener noise mechanism comes from avalanche, which > doesn't kick in until you get to voltages above about 8 volts. > Low-current "microplasmas" form and quickly terminate after > discharging the zener's self capacitance, creating a kind of > popcorn noise. There are extensive threads on the subject > 15-20 years ago on s.e.d., where I spent a month (haha, more) > making and posting all kinds of nanosecond-scale measurements. > > The zener physics effect (field emission) predominates at > low-voltages, see the ON Semi handbook, HBD854, page 20. > https://www.onsemi.com/pub/Collateral/HBD854-D.PDF > > > -- > Thanks, > - Win
Grin.. everyone should spend a month playing with avalanche breakdown. Say Win, If you want to "waste" a few more hours with avalanches, I can send you some LED's that breakdown ~25 Volts and are single photon detectors. (Spad's) They make great little experiments for electronics courses. (perhaps Paul would be more interested?) These.. you can also get them from Newark. http://www.purdyelectronics.com/pdf/AND113R.pdf A newsletter. http://nebula.wsimg.com/0b846f1e91ab9c7442a61c8c35680a51?AccessKeyId=027C3581808C75E81679&disposition=0&alloworigin=1 George H.
Winfield Hill wrote...
> >George Herold wrote... >> >>On Wednesday, March 16, 2016 at 1:53:11 AM UTC-4, David Eather wrote: >>> If any kind soul can help... >>> >>> There was a short post/note on SED or SEB about a transistor with a 2.5V >>> max Vebo and another one with 3.0 max Vebo. I have spent hours looking for >>> the transistors and have run out of options. Does anyone remember which >>> transistor numbers these were? >>> >>> I'm adding transistor junction breakdown noise to a Arduino and they would >>> fit the bill perfectly - and cut out problem of providing extra voltage >>> sources other than %v power from USB. >>> >>> As always TIA. >> >> I don't know the transistors, but have you tried a low voltage zener. >> (The problem with both is that you may not get much more than just the >> shot noise.) > > Agreed, the zener noise mechanism comes from avalanche, which > doesn't kick in until you get to voltages above about 8 volts. > Low-current "microplasmas" form and quickly terminate after > discharging the zener's self capacitance, creating a kind of > popcorn noise. There are extensive threads on the subject > 15-20 years ago on s.e.d., where I spent a month (haha, more) > making and posting all kinds of nanosecond-scale measurements. > > The zener physics effect (field emission) predominates at > low-voltages, see the ON Semi handbook, HBD854, page 20. > https://www.onsemi.com/pub/Collateral/HBD854-D.PDF
One suggestion: 1.2-volt Vbe voltage references are more noisy than resistors and transistors, etc., due to the 10x voltage step-up intrinsic to their design. If the reference's circuitry runs at low currents, it's even more noisy. The LMV431 with a 50uA core has 230nV/rt-Hz noise. The LM385-1.2, with its core under 10uA shows 400nV/rt-Hz. The REF1112 that runs at 1uA should be even more noisy. The lower-current types will suffer from limited frequency response. Although the noise level is not specified, the basic physics behind BJT transistor noise at low currents (see AoE III, page 481 and especially Figures 8.12, and 8.57) means you may get much better part-to-part consistency than you could get with a zener diode. David, if you try this, let us know what you learn. -- Thanks, - Win
George Herold wrote...
> >On Wednesday, March 16, 2016 at 10:33:03 AM UTC-4, Winfield Hill wrote: >> George Herold wrote... >> > >> >On Wednesday, March 16, 2016 at 1:53:11 AM UTC-4, David Eather wrote: >> >> If any kind soul can help... >> >> >> >> There was a short post/note on SED or SEB about a transistor with a 2.5V >>>> max Vebo and another one with 3.0 max Vebo. I have spent hours looking for >> >> the transistors and have run out of options. Does anyone remember which >> >> transistor numbers these were? >> >> >>>> I'm adding transistor junction breakdown noise to a Arduino and they would >> >> fit the bill perfectly - and cut out problem of providing extra voltage >> >> sources other than %v power from USB. >> >> >> >> As always TIA. >> > >> > I don't know the transistors, but have you tried a low voltage zener. >> > (The problem with both is that you may not get much more than just the >> > shot noise.) >> >> Agreed, the zener noise mechanism comes from avalanche, which >> doesn't kick in until you get to voltages above about 8 volts. >> Low-current "microplasmas" form and quickly terminate after >> discharging the zener's self capacitance, creating a kind of >> popcorn noise. There are extensive threads on the subject >> 15-20 years ago on s.e.d., where I spent a month (haha, more) >> making and posting all kinds of nanosecond-scale measurements. >> >> The zener physics effect (field emission) predominates at >> low-voltages, see the ON Semi handbook, HBD854, page 20. >> https://www.onsemi.com/pub/Collateral/HBD854-D.PDF >> >> >> -- >> Thanks, >> - Win > >Grin.. everyone should spend a month playing with avalanche breakdown. > >Say Win, If you want to "waste" a few more hours with avalanches, >I can send you some LED's that breakdown ~25 Volts and are >single photon detectors. (Spad's) They make great little experiments >for electronics courses. (perhaps Paul would be more interested?) >These.. you can also get them from Newark. >http://www.purdyelectronics.com/pdf/AND113R.pdf > >A newsletter. >http://nebula.wsimg.com/0b846f1e91ab9c7442a61c8c35680a51?AccessKeyId=027C3581808C75E81679&disposition=0&alloworigin=1 > >George H.
Awesome! -- Thanks, - Win
On Wed, 16 Mar 2016 15:53:04 +1000, "David Eather" <eather@tpg.com.au>
wrote:

>If any kind soul can help... > >There was a short post/note on SED or SEB about a transistor with a 2.5V >max Vebo and another one with 3.0 max Vebo. I have spent hours looking for >the transistors and have run out of options. Does anyone remember which >transistor numbers these were? > >I'm adding transistor junction breakdown noise to a Arduino and they would >fit the bill perfectly - and cut out problem of providing extra voltage >sources other than %v power from USB. > >As always TIA.
Just because it's rated for 2.5 volts max doesn't mean it will conduct at 2.5 or even 5 volts. There are other noise sources that don't need a lot of voltge. What do you want to use the noise for? -- John Larkin Highland Technology, Inc lunatic fringe electronics
On Thu, 17 Mar 2016 00:16:22 +1000, David Eather wrote:

> On Wed, 16 Mar 2016 23:04:13 +1000, George Herold > <gherold@teachspin.com> wrote: > >> On Wednesday, March 16, 2016 at 1:53:11 AM UTC-4, David Eather wrote: >>> If any kind soul can help... >>> >>> There was a short post/note on SED or SEB about a transistor with a >>> 2.5V max Vebo and another one with 3.0 max Vebo. I have spent hours >>> looking for the transistors and have run out of options. Does anyone >>> remember which transistor numbers these were? >>> >>> I'm adding transistor junction breakdown noise to a Arduino and they >>> would fit the bill perfectly - and cut out problem of providing extra >>> voltage sources other than %v power from USB. >>> >>> As always TIA. >> >> I don't know the transistors, but have you tried a low voltage zener. >> (The problem with both is that you may not get much more than just the >> shot noise.) >> >> George H. > > Zener is OK but my experiments suggest noise is about an order of > magnitude lower. On the plus side transistor junctions seem to 'age' and > become quieter as time goes on. (both effects may be non-existent and > just the result of my poor experiments)
We had a reverse-biased BE junction noise generator in an old product fail after several years in the field. The problem was that the statistical tests on the entropy source failed yet the DC measurements on the transistor seemed fine when a technician looked at it. The stats came good once the part was changed for a new one. I guess one shouldn't expect too much when using a device outside its abs. max. ratings. Allan