On a sunny day (Sun, 10 Sep 2023 13:56:54 +0100) it happened Piglet <erichpwagner@hotmail.com> wrote in <udkeen$isne$1@dont-email.me>:>On 06/09/2023 03:38, John Larkin wrote: >> On Wed, 6 Sep 2023 02:31:04 -0000 (UTC), Phil Hobbs >> <pcdhSpamMeSenseless@electrooptical.net> wrote: >> >>> John Larkin <jlarkin@highlandSNIPMEtechnology.com> wrote: >>>> On Wed, 6 Sep 2023 00:58:11 -0000 (UTC), Jasen Betts >>>> <usenet@revmaps.no-ip.org> wrote: >>>> >>>>> On 2023-09-06, John Larkin <jlarkin@highlandSNIPMEtechnology.com> wrote: >>>>>> Imagine an NPN transistor. Ground the emitter and connect the >>>>>> collector to some nice positive voltage. >>>>>> >>>>>> Now pull the base negative, through a current-limiting resistor. What >>>>>> happens? >>>>> >>>>> Nothing until you exceed the emitter base reverse breakdown (or >>>>> collector base breakdown) voltage, >>>> >>>> Not literally nothing, but not much interesting. It gets more >>>> interesting when the base zeners. >>>> >>>>> >>>>> Bitter-base is usually about 5V >>>>> >>>>> Behaves kind of like a zener diode and damages the transistor. >>>> >>>> The base current is limited. But what happens? >>>> >>>> >>> >>> Haven’t tried it, at least not on purpose, but I’d guess that when the >>> avalanche starts, most of the electrons will get sucked up by the >>> collector. >>> >>> Since it’s the electrons and not the holes that do the avalanching in >>> silicon, that might partially suppress the avalanche. If that were true, >>> putting a positive voltage on the collector would make the base voltage >>> slightly more negative. >>> >>> Cheers >>> >>> Phil Hobbs >> >> I'd expect that zenering fills the b-e junction with lots of carriers, >> and some find their way into the collector. I don't know how many. >> >> Probably a lot less than foward base current. >> >> I suppose I should try it. >> > >Did you try it? I did today with a junk box NPN and results are kind of >as expected: > ><https://www.dropbox.com/scl/fi/rqr7n3uunosswqhx4e59h/NPNunusualQuadrant.pdf?rlkey=6kcqwz3soawgxws2ouhbdktq3&raw=1>Interesting!
NPN in unusual quadrant
Started by ●September 5, 2023
Reply by ●September 10, 20232023-09-10
Reply by ●September 10, 20232023-09-10
On 10/09/2023 15:44, Ricky wrote:> On Sunday, September 10, 2023 at 8:57:03 AM UTC-4, Piglet wrote: >> On 06/09/2023 03:38, John Larkin wrote: >>> On Wed, 6 Sep 2023 02:31:04 -0000 (UTC), Phil Hobbs >>> <pcdhSpamM...@electrooptical.net> wrote: >>> >>>> John Larkin <jla...@highlandSNIPMEtechnology.com> wrote: >>>>> On Wed, 6 Sep 2023 00:58:11 -0000 (UTC), Jasen Betts >>>>> <use...@revmaps.no-ip.org> wrote: >>>>> >>>>>> On 2023-09-06, John Larkin <jla...@highlandSNIPMEtechnology.com> wrote: >>>>>>> Imagine an NPN transistor. Ground the emitter and connect the >>>>>>> collector to some nice positive voltage. >>>>>>> >>>>>>> Now pull the base negative, through a current-limiting resistor. What >>>>>>> happens? >>>>>> >>>>>> Nothing until you exceed the emitter base reverse breakdown (or >>>>>> collector base breakdown) voltage, >>>>> >>>>> Not literally nothing, but not much interesting. It gets more >>>>> interesting when the base zeners. >>>>> >>>>>> >>>>>> Bitter-base is usually about 5V >>>>>> >>>>>> Behaves kind of like a zener diode and damages the transistor. >>>>> >>>>> The base current is limited. But what happens? >>>>> >>>>> >>>> >>>> Haven’t tried it, at least not on purpose, but I’d guess that when the >>>> avalanche starts, most of the electrons will get sucked up by the >>>> collector. >>>> >>>> Since it’s the electrons and not the holes that do the avalanching in >>>> silicon, that might partially suppress the avalanche. If that were true, >>>> putting a positive voltage on the collector would make the base voltage >>>> slightly more negative. >>>> >>>> Cheers >>>> >>>> Phil Hobbs >>> >>> I'd expect that zenering fills the b-e junction with lots of carriers, >>> and some find their way into the collector. I don't know how many. >>> >>> Probably a lot less than foward base current. >>> >>> I suppose I should try it. >>> >> Did you try it? I did today with a junk box NPN and results are kind of >> as expected: >> >> <https://www.dropbox.com/scl/fi/rqr7n3uunosswqhx4e59h/NPNunusualQuadrant.pdf?rlkey=6kcqwz3soawgxws2ouhbdktq3&raw=1> > > Does the collector current go through the base, or the emitter? >I took the photo of those measurements before trying changing the collector voltage supply. Ic did not change from the Vc=10V value despite varying Vc from zero to 20V. I think that ties in with the collector current being the photo-diode effect in the CB junction and so therefore the return path would be through the base wire. piglet
Reply by ●September 10, 20232023-09-10
On Sunday, September 10, 2023 at 7:57:03 AM UTC-5, Piglet wrote:> On 06/09/2023 03:38, John Larkin wrote: > > On Wed, 6 Sep 2023 02:31:04 -0000 (UTC), Phil Hobbs > > <pcdhSpamM...@electrooptical.net> wrote: > > > >> John Larkin <jla...@highlandSNIPMEtechnology.com> wrote: > >>> On Wed, 6 Sep 2023 00:58:11 -0000 (UTC), Jasen Betts > >>> <use...@revmaps.no-ip.org> wrote: > >>> > >>>> On 2023-09-06, John Larkin <jla...@highlandSNIPMEtechnology.com> wrote: > >>>>> Imagine an NPN transistor. Ground the emitter and connect the > >>>>> collector to some nice positive voltage. > >>>>> > >>>>> Now pull the base negative, through a current-limiting resistor. What > >>>>> happens? > >>>> > >>>> Nothing until you exceed the emitter base reverse breakdown (or > >>>> collector base breakdown) voltage, > >>> > >>> Not literally nothing, but not much interesting. It gets more > >>> interesting when the base zeners. > >>> > >>>> > >>>> Bitter-base is usually about 5V > >>>> > >>>> Behaves kind of like a zener diode and damages the transistor. > >>> > >>> The base current is limited. But what happens? > >>> > >>> > >> > >> Haven’t tried it, at least not on purpose, but I’d guess that when the > >> avalanche starts, most of the electrons will get sucked up by the > >> collector. > >> > >> Since it’s the electrons and not the holes that do the avalanching in > >> silicon, that might partially suppress the avalanche. If that were true, > >> putting a positive voltage on the collector would make the base voltage > >> slightly more negative. > >> > >> Cheers > >> > >> Phil Hobbs > > > > I'd expect that zenering fills the b-e junction with lots of carriers, > > and some find their way into the collector. I don't know how many. > > > > Probably a lot less than foward base current. > > > > I suppose I should try it. > > > Did you try it? I did today with a junk box NPN and results are kind of > as expected: > > <https://www.dropbox.com/scl/fi/rqr7n3uunosswqhx4e59h/NPNunusualQuadrant.pdf?rlkey=6kcqwz3soawgxws2ouhbdktq3&raw=1> > > pigletVery good, Piglet. That is very linear which I did not expect. Your data results in Ic(nA) = 9.2536Veb - 74.33
Reply by ●September 11, 20232023-09-11
On Sunday, September 10, 2023 at 12:55:12 PM UTC-7, John Smiht wrote:> On Sunday, September 10, 2023 at 7:57:03 AM UTC-5, Piglet wrote: > > On 06/09/2023 03:38, John Larkin wrote: > > > On Wed, 6 Sep 2023 02:31:04 -0000 (UTC), Phil Hobbs > > > <pcdhSpamM...@electrooptical.net> wrote: > > > > > >> John Larkin <jla...@highlandSNIPMEtechnology.com> wrote:> > >>>>> Now pull the base negative, through a current-limiting resistor. What > > >>>>> happens? > > >>>> > > >>>> Nothing until you exceed the emitter base reverse breakdown (or > > >>>> collector base breakdown) voltage, > > >>> > > >>> Not literally nothing, but not much interesting. It gets more > > >>> interesting when the base zeners. > > >>> > > >>>> > > >>>> Bitter-base is usually about 5V > > >>>> > > >>>> Behaves kind of like a zener diode and damages the transistor.> > >> Haven’t tried it, at least not on purpose, but I’d guess that when the > > >> avalanche starts, most of the electrons will get sucked up by the > > >> collector. > > >> > > >> Since it’s the electrons and not the holes that do the avalanching in > > >> silicon, that might partially suppress the avalanche. If that were true, > > >> putting a positive voltage on the collector would make the base voltage > > >> slightly more negative. > > >> > > >> Cheers > > >> > > >> Phil Hobbs > > > > > > I'd expect that zenering fills the b-e junction with lots of carriers, > > > and some find their way into the collector. I don't know how many. > > > > > > Probably a lot less than foward base current. > > > > > > I suppose I should try it. > > > > > Did you try it? I did today with a junk box NPN and results are kind of > > as expected: > > > > <https://www.dropbox.com/scl/fi/rqr7n3uunosswqhx4e59h/NPNunusualQuadrant.pdf?rlkey=6kcqwz3soawgxws2ouhbdktq3&raw=1>> Very good, Piglet. That is very linear which I did not expect. Your data results in > Ic(nA) = 9.2536Veb - 74.33So, to expect this in future, should we assume the B-E breakdown creates light, and the collector current is a photodiode detecting that light? That does explain the effect, and predicts emitter current proportional to collector current.
Reply by ●September 11, 20232023-09-11
On 11/09/2023 4:16 am, whit3rd wrote:> On Sunday, September 10, 2023 at 12:55:12 PM UTC-7, John Smiht wrote: >> On Sunday, September 10, 2023 at 7:57:03 AM UTC-5, Piglet wrote: >>> On 06/09/2023 03:38, John Larkin wrote: >>>> On Wed, 6 Sep 2023 02:31:04 -0000 (UTC), Phil Hobbs >>>> <pcdhSpamM...@electrooptical.net> wrote: >>>> >>>>> John Larkin <jla...@highlandSNIPMEtechnology.com> wrote: > >>>>>>>> Now pull the base negative, through a current-limiting resistor. What >>>>>>>> happens? >>>>>>> >>>>>>> Nothing until you exceed the emitter base reverse breakdown (or >>>>>>> collector base breakdown) voltage, >>>>>> >>>>>> Not literally nothing, but not much interesting. It gets more >>>>>> interesting when the base zeners. >>>>>> >>>>>>> >>>>>>> Bitter-base is usually about 5V >>>>>>> >>>>>>> Behaves kind of like a zener diode and damages the transistor. > >>>>> Haven’t tried it, at least not on purpose, but I’d guess that when the >>>>> avalanche starts, most of the electrons will get sucked up by the >>>>> collector. >>>>> >>>>> Since it’s the electrons and not the holes that do the avalanching in >>>>> silicon, that might partially suppress the avalanche. If that were true, >>>>> putting a positive voltage on the collector would make the base voltage >>>>> slightly more negative. >>>>> >>>>> Cheers >>>>> >>>>> Phil Hobbs >>>> >>>> I'd expect that zenering fills the b-e junction with lots of carriers, >>>> and some find their way into the collector. I don't know how many. >>>> >>>> Probably a lot less than foward base current. >>>> >>>> I suppose I should try it. >>>> >>> Did you try it? I did today with a junk box NPN and results are kind of >>> as expected: >>> >>> <https://www.dropbox.com/scl/fi/rqr7n3uunosswqhx4e59h/NPNunusualQuadrant.pdf?rlkey=6kcqwz3soawgxws2ouhbdktq3&raw=1> > >> Very good, Piglet. That is very linear which I did not expect. Your data results in >> Ic(nA) = 9.2536Veb - 74.33 > > So, to expect this in future, should we assume the B-E breakdown creates light, and > the collector current is a photodiode detecting that light? That does explain the > effect, and predicts emitter current proportional to collector current.Yes, I think you meant collector current proportional to emitter current? We did discusss all this back in 2015 under the thread "a very silly circuit". About 25 years ago I think Stephen Woodward posted a design idea in ED magazine using the effect to create a tiny negative bias for opamp offset nulling in a positive rail only environment. piglet
Reply by ●September 11, 20232023-09-11
On Sun, 10 Sep 2023 13:56:54 +0100, Piglet <erichpwagner@hotmail.com> wrote:>On 06/09/2023 03:38, John Larkin wrote: >> On Wed, 6 Sep 2023 02:31:04 -0000 (UTC), Phil Hobbs >> <pcdhSpamMeSenseless@electrooptical.net> wrote: >> >>> John Larkin <jlarkin@highlandSNIPMEtechnology.com> wrote: >>>> On Wed, 6 Sep 2023 00:58:11 -0000 (UTC), Jasen Betts >>>> <usenet@revmaps.no-ip.org> wrote: >>>> >>>>> On 2023-09-06, John Larkin <jlarkin@highlandSNIPMEtechnology.com> wrote: >>>>>> Imagine an NPN transistor. Ground the emitter and connect the >>>>>> collector to some nice positive voltage. >>>>>> >>>>>> Now pull the base negative, through a current-limiting resistor. What >>>>>> happens? >>>>> >>>>> Nothing until you exceed the emitter base reverse breakdown (or >>>>> collector base breakdown) voltage, >>>> >>>> Not literally nothing, but not much interesting. It gets more >>>> interesting when the base zeners. >>>> >>>>> >>>>> Bitter-base is usually about 5V >>>>> >>>>> Behaves kind of like a zener diode and damages the transistor. >>>> >>>> The base current is limited. But what happens? >>>> >>>> >>> >>> Haven�t tried it, at least not on purpose, but I�d guess that when the >>> avalanche starts, most of the electrons will get sucked up by the >>> collector. >>> >>> Since it�s the electrons and not the holes that do the avalanching in >>> silicon, that might partially suppress the avalanche. If that were true, >>> putting a positive voltage on the collector would make the base voltage >>> slightly more negative. >>> >>> Cheers >>> >>> Phil Hobbs >> >> I'd expect that zenering fills the b-e junction with lots of carriers, >> and some find their way into the collector. I don't know how many. >> >> Probably a lot less than foward base current. >> >> I suppose I should try it. >> > >Did you try it? I did today with a junk box NPN and results are kind of >as expected: > ><https://www.dropbox.com/scl/fi/rqr7n3uunosswqhx4e59h/NPNunusualQuadrant.pdf?rlkey=6kcqwz3soawgxws2ouhbdktq3&raw=1> > >pigletThere's some fences around here that only the privileged will be allowed to paint. I have a few tickets left . RL
Reply by ●September 11, 20232023-09-11
On Mon, 11 Sep 2023 11:01:46 +0100, piglet <erichpwagner@hotmail.com> wrote:>On 11/09/2023 4:16 am, whit3rd wrote: >> On Sunday, September 10, 2023 at 12:55:12?PM UTC-7, John Smiht wrote: >>> On Sunday, September 10, 2023 at 7:57:03?AM UTC-5, Piglet wrote: >>>> On 06/09/2023 03:38, John Larkin wrote: >>>>> On Wed, 6 Sep 2023 02:31:04 -0000 (UTC), Phil Hobbs >>>>> <pcdhSpamM...@electrooptical.net> wrote: >>>>> >>>>>> John Larkin <jla...@highlandSNIPMEtechnology.com> wrote: >> >>>>>>>>> Now pull the base negative, through a current-limiting resistor. What >>>>>>>>> happens? >>>>>>>> >>>>>>>> Nothing until you exceed the emitter base reverse breakdown (or >>>>>>>> collector base breakdown) voltage, >>>>>>> >>>>>>> Not literally nothing, but not much interesting. It gets more >>>>>>> interesting when the base zeners. >>>>>>> >>>>>>>> >>>>>>>> Bitter-base is usually about 5V >>>>>>>> >>>>>>>> Behaves kind of like a zener diode and damages the transistor. >> >>>>>> Haven�t tried it, at least not on purpose, but I�d guess that when the >>>>>> avalanche starts, most of the electrons will get sucked up by the >>>>>> collector. >>>>>> >>>>>> Since it�s the electrons and not the holes that do the avalanching in >>>>>> silicon, that might partially suppress the avalanche. If that were true, >>>>>> putting a positive voltage on the collector would make the base voltage >>>>>> slightly more negative. >>>>>> >>>>>> Cheers >>>>>> >>>>>> Phil Hobbs >>>>> >>>>> I'd expect that zenering fills the b-e junction with lots of carriers, >>>>> and some find their way into the collector. I don't know how many. >>>>> >>>>> Probably a lot less than foward base current. >>>>> >>>>> I suppose I should try it. >>>>> >>>> Did you try it? I did today with a junk box NPN and results are kind of >>>> as expected: >>>> >>>> <https://www.dropbox.com/scl/fi/rqr7n3uunosswqhx4e59h/NPNunusualQuadrant.pdf?rlkey=6kcqwz3soawgxws2ouhbdktq3&raw=1> >> >>> Very good, Piglet. That is very linear which I did not expect. Your data results in >>> Ic(nA) = 9.2536Veb - 74.33 >> >> So, to expect this in future, should we assume the B-E breakdown creates light, and >> the collector current is a photodiode detecting that light? That does explain the >> effect, and predicts emitter current proportional to collector current. > >Yes, I think you meant collector current proportional to emitter >current? We did discusss all this back in 2015 under the thread "a very >silly circuit". About 25 years ago I think Stephen Woodward posted a >design idea in ED magazine using the effect to create a tiny negative >bias for opamp offset nulling in a positive rail only environment. > >pigletPV optocouplers are great for genereating a quiet floating voltage, but a transistor is cheaper. I guess a regular, transistor type optocoupler, will generate a floating voltage too. Something else to try.
Reply by ●September 11, 20232023-09-11
On 2023-09-11 08:32, John Larkin wrote:> On Mon, 11 Sep 2023 11:01:46 +0100, piglet <erichpwagner@hotmail.com> > wrote: > >> On 11/09/2023 4:16 am, whit3rd wrote: >>> On Sunday, September 10, 2023 at 12:55:12?PM UTC-7, John Smiht wrote: >>>> On Sunday, September 10, 2023 at 7:57:03?AM UTC-5, Piglet wrote: >>>>> On 06/09/2023 03:38, John Larkin wrote: >>>>>> On Wed, 6 Sep 2023 02:31:04 -0000 (UTC), Phil Hobbs >>>>>> <pcdhSpamM...@electrooptical.net> wrote: >>>>>> >>>>>>> John Larkin <jla...@highlandSNIPMEtechnology.com> wrote: >>> >>>>>>>>>> Now pull the base negative, through a current-limiting resistor. What >>>>>>>>>> happens? >>>>>>>>> >>>>>>>>> Nothing until you exceed the emitter base reverse breakdown (or >>>>>>>>> collector base breakdown) voltage, >>>>>>>> >>>>>>>> Not literally nothing, but not much interesting. It gets more >>>>>>>> interesting when the base zeners. >>>>>>>> >>>>>>>>> >>>>>>>>> Bitter-base is usually about 5V >>>>>>>>> >>>>>>>>> Behaves kind of like a zener diode and damages the transistor. >>> >>>>>>> Haven’t tried it, at least not on purpose, but I’d guess that when the >>>>>>> avalanche starts, most of the electrons will get sucked up by the >>>>>>> collector. >>>>>>> >>>>>>> Since it’s the electrons and not the holes that do the avalanching in >>>>>>> silicon, that might partially suppress the avalanche. If that were true, >>>>>>> putting a positive voltage on the collector would make the base voltage >>>>>>> slightly more negative. >>>>>>> >>>>>>> Cheers >>>>>>> >>>>>>> Phil Hobbs >>>>>> >>>>>> I'd expect that zenering fills the b-e junction with lots of carriers, >>>>>> and some find their way into the collector. I don't know how many. >>>>>> >>>>>> Probably a lot less than foward base current. >>>>>> >>>>>> I suppose I should try it. >>>>>> >>>>> Did you try it? I did today with a junk box NPN and results are kind of >>>>> as expected: >>>>> >>>>> <https://www.dropbox.com/scl/fi/rqr7n3uunosswqhx4e59h/NPNunusualQuadrant.pdf?rlkey=6kcqwz3soawgxws2ouhbdktq3&raw=1> >>> >>>> Very good, Piglet. That is very linear which I did not expect. Your data results in >>>> Ic(nA) = 9.2536Veb - 74.33 >>> >>> So, to expect this in future, should we assume the B-E breakdown creates light, and >>> the collector current is a photodiode detecting that light? That does explain the >>> effect, and predicts emitter current proportional to collector current. >> >> Yes, I think you meant collector current proportional to emitter >> current? We did discusss all this back in 2015 under the thread "a very >> silly circuit". About 25 years ago I think Stephen Woodward posted a >> design idea in ED magazine using the effect to create a tiny negative >> bias for opamp offset nulling in a positive rail only environment. >> >> piglet > > PV optocouplers are great for genereating a quiet floating voltage, > but a transistor is cheaper. > > I guess a regular, transistor type optocoupler, will generate a > floating voltage too. Something else to try. >It will, but you have to accept an efficiency on the order of CTR/beta, i.e. something below 0.1%. Cheers Phil Hobbs -- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC / Hobbs ElectroOptics Optics, Electro-optics, Photonics, Analog Electronics Briarcliff Manor NY 10510 http://electrooptical.net http://hobbs-eo.com
Reply by ●September 11, 20232023-09-11
On 2023-09-11 08:30, legg wrote:> On Sun, 10 Sep 2023 13:56:54 +0100, Piglet <erichpwagner@hotmail.com> > wrote: > >> On 06/09/2023 03:38, John Larkin wrote: >>> On Wed, 6 Sep 2023 02:31:04 -0000 (UTC), Phil Hobbs >>> <pcdhSpamMeSenseless@electrooptical.net> wrote: >>> >>>> John Larkin <jlarkin@highlandSNIPMEtechnology.com> wrote: >>>>> On Wed, 6 Sep 2023 00:58:11 -0000 (UTC), Jasen Betts >>>>> <usenet@revmaps.no-ip.org> wrote: >>>>> >>>>>> On 2023-09-06, John Larkin <jlarkin@highlandSNIPMEtechnology.com> wrote: >>>>>>> Imagine an NPN transistor. Ground the emitter and connect the >>>>>>> collector to some nice positive voltage. >>>>>>> >>>>>>> Now pull the base negative, through a current-limiting resistor. What >>>>>>> happens? >>>>>> >>>>>> Nothing until you exceed the emitter base reverse breakdown (or >>>>>> collector base breakdown) voltage, >>>>> >>>>> Not literally nothing, but not much interesting. It gets more >>>>> interesting when the base zeners. >>>>> >>>>>> >>>>>> Bitter-base is usually about 5V >>>>>> >>>>>> Behaves kind of like a zener diode and damages the transistor. >>>>> >>>>> The base current is limited. But what happens? >>>>> >>>>> >>>> >>>> Haven’t tried it, at least not on purpose, but I’d guess that when the >>>> avalanche starts, most of the electrons will get sucked up by the >>>> collector. >>>> >>>> Since it’s the electrons and not the holes that do the avalanching in >>>> silicon, that might partially suppress the avalanche. If that were true, >>>> putting a positive voltage on the collector would make the base voltage >>>> slightly more negative. >>>> >>>> Cheers >>>> >>>> Phil Hobbs >>> >>> I'd expect that zenering fills the b-e junction with lots of carriers, >>> and some find their way into the collector. I don't know how many. >>> >>> Probably a lot less than foward base current. >>> >>> I suppose I should try it. >>> >> >> Did you try it? I did today with a junk box NPN and results are kind of >> as expected: >> >> <https://www.dropbox.com/scl/fi/rqr7n3uunosswqhx4e59h/NPNunusualQuadrant.pdf?rlkey=6kcqwz3soawgxws2ouhbdktq3&raw=1> >> >> piglet > > There's some fences around here that only the privileged will > be allowed to paint. > > I have a few tickets left . > > RL >Well, you can go fishing any day. ;) Cheers Phil Hobbs
Reply by ●September 11, 20232023-09-11
On Mon, 11 Sep 2023 08:50:54 -0400, Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:>On 2023-09-11 08:32, John Larkin wrote: >> On Mon, 11 Sep 2023 11:01:46 +0100, piglet <erichpwagner@hotmail.com> >> wrote: >> >>> On 11/09/2023 4:16 am, whit3rd wrote: >>>> On Sunday, September 10, 2023 at 12:55:12?PM UTC-7, John Smiht wrote: >>>>> On Sunday, September 10, 2023 at 7:57:03?AM UTC-5, Piglet wrote: >>>>>> On 06/09/2023 03:38, John Larkin wrote: >>>>>>> On Wed, 6 Sep 2023 02:31:04 -0000 (UTC), Phil Hobbs >>>>>>> <pcdhSpamM...@electrooptical.net> wrote: >>>>>>> >>>>>>>> John Larkin <jla...@highlandSNIPMEtechnology.com> wrote: >>>> >>>>>>>>>>> Now pull the base negative, through a current-limiting resistor. What >>>>>>>>>>> happens? >>>>>>>>>> >>>>>>>>>> Nothing until you exceed the emitter base reverse breakdown (or >>>>>>>>>> collector base breakdown) voltage, >>>>>>>>> >>>>>>>>> Not literally nothing, but not much interesting. It gets more >>>>>>>>> interesting when the base zeners. >>>>>>>>> >>>>>>>>>> >>>>>>>>>> Bitter-base is usually about 5V >>>>>>>>>> >>>>>>>>>> Behaves kind of like a zener diode and damages the transistor. >>>> >>>>>>>> Haven�t tried it, at least not on purpose, but I�d guess that when the >>>>>>>> avalanche starts, most of the electrons will get sucked up by the >>>>>>>> collector. >>>>>>>> >>>>>>>> Since it�s the electrons and not the holes that do the avalanching in >>>>>>>> silicon, that might partially suppress the avalanche. If that were true, >>>>>>>> putting a positive voltage on the collector would make the base voltage >>>>>>>> slightly more negative. >>>>>>>> >>>>>>>> Cheers >>>>>>>> >>>>>>>> Phil Hobbs >>>>>>> >>>>>>> I'd expect that zenering fills the b-e junction with lots of carriers, >>>>>>> and some find their way into the collector. I don't know how many. >>>>>>> >>>>>>> Probably a lot less than foward base current. >>>>>>> >>>>>>> I suppose I should try it. >>>>>>> >>>>>> Did you try it? I did today with a junk box NPN and results are kind of >>>>>> as expected: >>>>>> >>>>>> <https://www.dropbox.com/scl/fi/rqr7n3uunosswqhx4e59h/NPNunusualQuadrant.pdf?rlkey=6kcqwz3soawgxws2ouhbdktq3&raw=1> >>>> >>>>> Very good, Piglet. That is very linear which I did not expect. Your data results in >>>>> Ic(nA) = 9.2536Veb - 74.33 >>>> >>>> So, to expect this in future, should we assume the B-E breakdown creates light, and >>>> the collector current is a photodiode detecting that light? That does explain the >>>> effect, and predicts emitter current proportional to collector current. >>> >>> Yes, I think you meant collector current proportional to emitter >>> current? We did discusss all this back in 2015 under the thread "a very >>> silly circuit". About 25 years ago I think Stephen Woodward posted a >>> design idea in ED magazine using the effect to create a tiny negative >>> bias for opamp offset nulling in a positive rail only environment. >>> >>> piglet >> >> PV optocouplers are great for genereating a quiet floating voltage, >> but a transistor is cheaper. >> >> I guess a regular, transistor type optocoupler, will generate a >> floating voltage too. Something else to try. >> > >It will, but you have to accept an efficiency on the order of CTR/beta, >i.e. something below 0.1%.One could parallel the c-b and b-e junctions. Might help a little.> >Cheers > >Phil HobbsOK for some tiny bias thing, probably not for running motors. This would be another curiosity measurement. You never know if such a thing might be useful some day.
