On Wednesday, September 6, 2023 at 2:59:10 PM UTC-5, John Larkin wrote:> On Wed, 6 Sep 2023 19:19:20 +0100, piglet <erichp...@hotmail.com> > wrote: > >On 06/09/2023 01:04, John Larkin 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? > >> > > > >If the collector is already positive > That was a stated condition > >and pullup resistor is not > >extremely high then I think not much detectable will happen even once > >the Veb junction breaks down. > "Detectable" can include amps or picoamps of currents. > > Curious that nobody seems to address this case.How could the information be used? It seems to have not been needed in the past, yes?
NPN in unusual quadrant
Started by ●September 5, 2023
Reply by ●September 6, 20232023-09-06
Reply by ●September 6, 20232023-09-06
On Wed, 6 Sep 2023 14:34:12 -0700 (PDT), John Smiht <utube.jocjo@xoxy.net> wrote:>On Wednesday, September 6, 2023 at 2:59:10?PM UTC-5, John Larkin wrote: >> On Wed, 6 Sep 2023 19:19:20 +0100, piglet <erichp...@hotmail.com> >> wrote: >> >On 06/09/2023 01:04, John Larkin 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? >> >> >> > >> >If the collector is already positive >> That was a stated condition >> >and pullup resistor is not >> >extremely high then I think not much detectable will happen even once >> >the Veb junction breaks down. >> "Detectable" can include amps or picoamps of currents. >> >> Curious that nobody seems to address this case. > >How could the information be used? It seems to have not been needed in the past, yes?I'd expect that understanding transistors is a generally good thing to do. Looking at schematics on the web, it seems like few people do. If it behaves as I suspect it may, I might have a use for it.
Reply by ●September 6, 20232023-09-06
On 9/6/23 22:34, John Larkin wrote:> On Wed, 6 Sep 2023 14:34:12 -0700 (PDT), John Smiht > <utube.jocjo@xoxy.net> wrote: > >> On Wednesday, September 6, 2023 at 2:59:10?PM UTC-5, John Larkin wrote: >>> On Wed, 6 Sep 2023 19:19:20 +0100, piglet <erichp...@hotmail.com> >>> wrote: >>>> On 06/09/2023 01:04, John Larkin 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? >>>>> >>>> >>>> If the collector is already positive >>> That was a stated condition >>>> and pullup resistor is not >>>> extremely high then I think not much detectable will happen even once >>>> the Veb junction breaks down. >>> "Detectable" can include amps or picoamps of currents. >>> >>> Curious that nobody seems to address this case. >> >> How could the information be used? It seems to have not been needed in the past, yes? > > I'd expect that understanding transistors is a generally good thing to > do. Looking at schematics on the web, it seems like few people do. > > If it behaves as I suspect it may, I might have a use for it. >Back in the 60's/70's there were some germanium transistors marketed for avalanche pulse generator work. May have been Mullard / Philips, but don't remember any circuit details. Years ago, found myself fixing more than a few high power audio amps and built a simple breakdown tester with a variac, stepdown transformer, limiting resistor and full wave rectifer. Got some interesting effects at breakdown, very high frequency oscillation on the scope. 2n3055 class power devices, normally quite low frequency use. Interesting effect, perhaps similar to other weird stuff of the time, like impatt diodes... Chris
Reply by ●September 6, 20232023-09-06
On Wed, 6 Sep 2023 22:56:12 +0000, chrisq <devzero@nospam.com> wrote:>On 9/6/23 22:34, John Larkin wrote: >> On Wed, 6 Sep 2023 14:34:12 -0700 (PDT), John Smiht >> <utube.jocjo@xoxy.net> wrote: >> >>> On Wednesday, September 6, 2023 at 2:59:10?PM UTC-5, John Larkin wrote: >>>> On Wed, 6 Sep 2023 19:19:20 +0100, piglet <erichp...@hotmail.com> >>>> wrote: >>>>> On 06/09/2023 01:04, John Larkin 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? >>>>>> >>>>> >>>>> If the collector is already positive >>>> That was a stated condition >>>>> and pullup resistor is not >>>>> extremely high then I think not much detectable will happen even once >>>>> the Veb junction breaks down. >>>> "Detectable" can include amps or picoamps of currents. >>>> >>>> Curious that nobody seems to address this case. >>> >>> How could the information be used? It seems to have not been needed in the past, yes? >> >> I'd expect that understanding transistors is a generally good thing to >> do. Looking at schematics on the web, it seems like few people do. >> >> If it behaves as I suspect it may, I might have a use for it. >> > >Back in the 60's/70's there were some germanium transistors >marketed for avalanche pulse generator work. May have been >Mullard / Philips, but don't remember any circuit details.Early Tek and HP sampling scopes used an avalanche transistor to drive the sampler. I think maybe Lumatron did that first.> >Years ago, found myself fixing more than a few high power >audio amps and built a simple breakdown tester with a variac, >stepdown transformer, limiting resistor and full wave rectifer. >Got some interesting effects at breakdown, very high frequency >oscillation on the scope. 2n3055 class power devices, normally >quite low frequency use. Interesting effect, perhaps similar >to other weird stuff of the time, like impatt diodes... > >ChrisTransistors do all sorts of fun stuff that's not on the label. Zetex makes SOT23 silicon transistors that are designed to avalanche. As in <1 ns, 300 volts, 60 amps. Some other tricks: unclamped inductor flyback avalanche zero volt saturation step-recovery effects stored charge effects inverse beta temp-compensated b-e zenering
Reply by ●September 7, 20232023-09-07
On a sunny day (Wed, 6 Sep 2023 22:56:12 +0000) it happened chrisq <devzero@nospam.com> wrote in <udb02d$2m6li$1@dont-email.me>:>On 9/6/23 22:34, John Larkin wrote: >> On Wed, 6 Sep 2023 14:34:12 -0700 (PDT), John Smiht >> <utube.jocjo@xoxy.net> wrote: >> >>> On Wednesday, September 6, 2023 at 2:59:10?PM UTC-5, John Larkin wrote: >>>> On Wed, 6 Sep 2023 19:19:20 +0100, piglet <erichp...@hotmail.com> >>>> wrote: >>>>> On 06/09/2023 01:04, John Larkin 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? >>>>>> >>>>> >>>>> If the collector is already positive >>>> That was a stated condition >>>>> and pullup resistor is not >>>>> extremely high then I think not much detectable will happen even once >>>>> the Veb junction breaks down. >>>> "Detectable" can include amps or picoamps of currents. >>>> >>>> Curious that nobody seems to address this case. >>> >>> How could the information be used? It seems to have not been needed in the past, yes? >> >> I'd expect that understanding transistors is a generally good thing to >> do. Looking at schematics on the web, it seems like few people do. >> >> If it behaves as I suspect it may, I might have a use for it. >> > >Back in the 60's/70's there were some germanium transistors >marketed for avalanche pulse generator work. May have been >Mullard / Philips, but don't remember any circuit details. > >Years ago, found myself fixing more than a few high power >audio amps and built a simple breakdown tester with a variac, >stepdown transformer, limiting resistor and full wave rectifer. >Got some interesting effects at breakdown, very high frequency >oscillation on the scope. 2n3055 class power devices, normally >quite low frequency use. Interesting effect, perhaps similar >to other weird stuff of the time, like impatt diodes...Yes, and not all 2N3055 were the same, different manufactures.. diffferent ft Build quite a few audio amps with those. https://en.m.wikipedia.org/wiki/2N3055 Same likely goes for John Larkin's experiment, And manufacturers can change process any time, not something recommended to use out of spec.
Reply by ●September 7, 20232023-09-07
On 9/6/2023 7:28 PM, John Larkin wrote:> On Wed, 6 Sep 2023 22:56:12 +0000, chrisq <devzero@nospam.com> wrote: > >> On 9/6/23 22:34, John Larkin wrote: >>> On Wed, 6 Sep 2023 14:34:12 -0700 (PDT), John Smiht >>> <utube.jocjo@xoxy.net> wrote: >>> >>>> On Wednesday, September 6, 2023 at 2:59:10?PM UTC-5, John Larkin wrote: >>>>> On Wed, 6 Sep 2023 19:19:20 +0100, piglet <erichp...@hotmail.com> >>>>> wrote: >>>>>> On 06/09/2023 01:04, John Larkin 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? >>>>>>> >>>>>> >>>>>> If the collector is already positive >>>>> That was a stated condition >>>>>> and pullup resistor is not >>>>>> extremely high then I think not much detectable will happen even once >>>>>> the Veb junction breaks down. >>>>> "Detectable" can include amps or picoamps of currents. >>>>> >>>>> Curious that nobody seems to address this case. >>>> >>>> How could the information be used? It seems to have not been needed in the past, yes? >>> >>> I'd expect that understanding transistors is a generally good thing to >>> do. Looking at schematics on the web, it seems like few people do. >>> >>> If it behaves as I suspect it may, I might have a use for it. >>> >> >> Back in the 60's/70's there were some germanium transistors >> marketed for avalanche pulse generator work. May have been >> Mullard / Philips, but don't remember any circuit details. > > Early Tek and HP sampling scopes used an avalanche transistor to drive > the sampler. I think maybe Lumatron did that first. > >> >> Years ago, found myself fixing more than a few high power >> audio amps and built a simple breakdown tester with a variac, >> stepdown transformer, limiting resistor and full wave rectifer. >> Got some interesting effects at breakdown, very high frequency >> oscillation on the scope. 2n3055 class power devices, normally >> quite low frequency use. Interesting effect, perhaps similar >> to other weird stuff of the time, like impatt diodes... >> >> Chris > > Transistors do all sorts of fun stuff that's not on the label. > > Zetex makes SOT23 silicon transistors that are designed to avalanche. > As in <1 ns, 300 volts, 60 amps. > > Some other tricks: > > unclamped inductor flyback avalanche > > zero volt saturation > > step-recovery effects > > stored charge effects > > inverse beta > > temp-compensated b-e zenering > >They can be used as current-controlled resistors in reverse-saturation mode, where the collector-emitter resistance becomes generally proportional to the base current.
Reply by ●September 7, 20232023-09-07
On Thursday, September 7, 2023 at 2:59:05 PM UTC+10, Jan Panteltje wrote:> On a sunny day (Wed, 6 Sep 2023 22:56:12 +0000) it happened chrisq <dev...@nospam.com> wrote in <udb02d$2m6li$1...@dont-email.me>: > >On 9/6/23 22:34, John Larkin wrote: > >> On Wed, 6 Sep 2023 14:34:12 -0700 (PDT), John Smiht <utube...@xoxy.net> wrote: > >>> On Wednesday, September 6, 2023 at 2:59:10?PM UTC-5, John Larkin wrote: > >>>> On Wed, 6 Sep 2023 19:19:20 +0100, piglet <erichp...@hotmail.com> wrote: > >>>>> On 06/09/2023 01:04, John Larkin wrote:> Yes, and not all 2N3055 were the same, different manufactures.. diffferent ft > Build quite a few audio amps with those. > https://en.m.wikipedia.org/wiki/2N3055 > > Same likely goes for John Larkin's experiment, > And manufacturers can change process any time, not something recommended to use out of spec.The Mototola 2N3055 was notoriously a much smaller and faster die than the RCA part, and correspondingly easier to blow up. I used it in home-brew audio amplifier and the output stage never blew up. -- Bill Sloman, Sydney
Reply by ●September 7, 20232023-09-07
On Thursday, 7 September 2023 at 00:28:31 UTC+1, John Larkin wrote:> On Wed, 6 Sep 2023 22:56:12 +0000, chrisq <dev...@nospam.com> wrote: > > >On 9/6/23 22:34, John Larkin wrote: > >> On Wed, 6 Sep 2023 14:34:12 -0700 (PDT), John Smiht > >> <utube...@xoxy.net> wrote: > >> > >>> On Wednesday, September 6, 2023 at 2:59:10?PM UTC-5, John Larkin wrote: > >>>> On Wed, 6 Sep 2023 19:19:20 +0100, piglet <erichp...@hotmail.com> > >>>> wrote: > >>>>> On 06/09/2023 01:04, John Larkin 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? > >>>>>> > >>>>> > >>>>> If the collector is already positive > >>>> That was a stated condition > >>>>> and pullup resistor is not > >>>>> extremely high then I think not much detectable will happen even once > >>>>> the Veb junction breaks down. > >>>> "Detectable" can include amps or picoamps of currents. > >>>> > >>>> Curious that nobody seems to address this case. > >>> > >>> How could the information be used? It seems to have not been needed in the past, yes? > >> > >> I'd expect that understanding transistors is a generally good thing to > >> do. Looking at schematics on the web, it seems like few people do. > >> > >> If it behaves as I suspect it may, I might have a use for it. > >> > > > >Back in the 60's/70's there were some germanium transistors > >marketed for avalanche pulse generator work. May have been > >Mullard / Philips, but don't remember any circuit details. > Early Tek and HP sampling scopes used an avalanche transistor to drive > the sampler. I think maybe Lumatron did that first. > > > >Years ago, found myself fixing more than a few high power > >audio amps and built a simple breakdown tester with a variac, > >stepdown transformer, limiting resistor and full wave rectifer. > >Got some interesting effects at breakdown, very high frequency > >oscillation on the scope. 2n3055 class power devices, normally > >quite low frequency use. Interesting effect, perhaps similar > >to other weird stuff of the time, like impatt diodes... > > > >Chris > Transistors do all sorts of fun stuff that's not on the label. > > Zetex makes SOT23 silicon transistors that are designed to avalanche. > As in <1 ns, 300 volts, 60 amps. > > Some other tricks: > > unclamped inductor flyback avalanche > > zero volt saturation > > step-recovery effects > > stored charge effects > > inverse beta > > temp-compensated b-e zeneringYou missed noise generation from eb breakdown. John
Reply by ●September 7, 20232023-09-07
On Thu, 7 Sep 2023 01:06:21 -0400, bitrex <user@example.net> wrote:>On 9/6/2023 7:28 PM, John Larkin wrote: >> On Wed, 6 Sep 2023 22:56:12 +0000, chrisq <devzero@nospam.com> wrote: >> >>> On 9/6/23 22:34, John Larkin wrote: >>>> On Wed, 6 Sep 2023 14:34:12 -0700 (PDT), John Smiht >>>> <utube.jocjo@xoxy.net> wrote: >>>> >>>>> On Wednesday, September 6, 2023 at 2:59:10?PM UTC-5, John Larkin wrote: >>>>>> On Wed, 6 Sep 2023 19:19:20 +0100, piglet <erichp...@hotmail.com> >>>>>> wrote: >>>>>>> On 06/09/2023 01:04, John Larkin 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? >>>>>>>> >>>>>>> >>>>>>> If the collector is already positive >>>>>> That was a stated condition >>>>>>> and pullup resistor is not >>>>>>> extremely high then I think not much detectable will happen even once >>>>>>> the Veb junction breaks down. >>>>>> "Detectable" can include amps or picoamps of currents. >>>>>> >>>>>> Curious that nobody seems to address this case. >>>>> >>>>> How could the information be used? It seems to have not been needed in the past, yes? >>>> >>>> I'd expect that understanding transistors is a generally good thing to >>>> do. Looking at schematics on the web, it seems like few people do. >>>> >>>> If it behaves as I suspect it may, I might have a use for it. >>>> >>> >>> Back in the 60's/70's there were some germanium transistors >>> marketed for avalanche pulse generator work. May have been >>> Mullard / Philips, but don't remember any circuit details. >> >> Early Tek and HP sampling scopes used an avalanche transistor to drive >> the sampler. I think maybe Lumatron did that first. >> >>> >>> Years ago, found myself fixing more than a few high power >>> audio amps and built a simple breakdown tester with a variac, >>> stepdown transformer, limiting resistor and full wave rectifer. >>> Got some interesting effects at breakdown, very high frequency >>> oscillation on the scope. 2n3055 class power devices, normally >>> quite low frequency use. Interesting effect, perhaps similar >>> to other weird stuff of the time, like impatt diodes... >>> >>> Chris >> >> Transistors do all sorts of fun stuff that's not on the label. >> >> Zetex makes SOT23 silicon transistors that are designed to avalanche. >> As in <1 ns, 300 volts, 60 amps. >> >> Some other tricks: >> >> unclamped inductor flyback avalanche >> >> zero volt saturation >> >> step-recovery effects >> >> stored charge effects >> >> inverse beta >> >> temp-compensated b-e zenering >> >> > >They can be used as current-controlled resistors in reverse-saturation >mode, where the collector-emitter resistance becomes generally >proportional to the base current. >Ohmic region? Cute.
Reply by ●September 7, 20232023-09-07
On Thu, 7 Sep 2023 04:22:41 -0700 (PDT), John Walliker <jrwalliker@gmail.com> wrote:>On Thursday, 7 September 2023 at 00:28:31 UTC+1, John Larkin wrote: >> On Wed, 6 Sep 2023 22:56:12 +0000, chrisq <dev...@nospam.com> wrote: >> >> >On 9/6/23 22:34, John Larkin wrote: >> >> On Wed, 6 Sep 2023 14:34:12 -0700 (PDT), John Smiht >> >> <utube...@xoxy.net> wrote: >> >> >> >>> On Wednesday, September 6, 2023 at 2:59:10?PM UTC-5, John Larkin wrote: >> >>>> On Wed, 6 Sep 2023 19:19:20 +0100, piglet <erichp...@hotmail.com> >> >>>> wrote: >> >>>>> On 06/09/2023 01:04, John Larkin 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? >> >>>>>> >> >>>>> >> >>>>> If the collector is already positive >> >>>> That was a stated condition >> >>>>> and pullup resistor is not >> >>>>> extremely high then I think not much detectable will happen even once >> >>>>> the Veb junction breaks down. >> >>>> "Detectable" can include amps or picoamps of currents. >> >>>> >> >>>> Curious that nobody seems to address this case. >> >>> >> >>> How could the information be used? It seems to have not been needed in the past, yes? >> >> >> >> I'd expect that understanding transistors is a generally good thing to >> >> do. Looking at schematics on the web, it seems like few people do. >> >> >> >> If it behaves as I suspect it may, I might have a use for it. >> >> >> > >> >Back in the 60's/70's there were some germanium transistors >> >marketed for avalanche pulse generator work. May have been >> >Mullard / Philips, but don't remember any circuit details. >> Early Tek and HP sampling scopes used an avalanche transistor to drive >> the sampler. I think maybe Lumatron did that first. >> > >> >Years ago, found myself fixing more than a few high power >> >audio amps and built a simple breakdown tester with a variac, >> >stepdown transformer, limiting resistor and full wave rectifer. >> >Got some interesting effects at breakdown, very high frequency >> >oscillation on the scope. 2n3055 class power devices, normally >> >quite low frequency use. Interesting effect, perhaps similar >> >to other weird stuff of the time, like impatt diodes... >> > >> >Chris >> Transistors do all sorts of fun stuff that's not on the label. >> >> Zetex makes SOT23 silicon transistors that are designed to avalanche. >> As in <1 ns, 300 volts, 60 amps. >> >> Some other tricks: >> >> unclamped inductor flyback avalanche >> >> zero volt saturation >> >> step-recovery effects >> >> stored charge effects >> >> inverse beta >> >> temp-compensated b-e zenering > >You missed noise generation from eb breakdown. >JohnRight. I was thinking that my original quadrant comment could suggest a mode where the b-e zener makes noise and the c-b junction amplifies it. That depends on where the zener-inspired carriers go. Somebody should try that. I can't do that this week or so.
