On 10/28/2018 10:16 PM, bitrex wrote:> On 10/28/2018 09:33 PM, jurb6006@gmail.com wrote: >>> ""youth", in quotes I'm just shy of 40" >> >> Wow, that explains why you're not conservative. You will be in about >> ten years, and don't worry, it doesn't hurt. >> > > I'm probably too long-time New Englander for that I'm afraid, why in the > world would I join a party so beloved by these whackjob "Real America" > holy-roller evangelicals? scumbag scam-artists the lot of 'em and anyone > who panders to themNot to mention habitual kid-touching perverts!"Moral Majority", that's a hoot.
pointers to transistor (semiconductor) curve tracer circuits/projects
Started by ●October 28, 2018
Reply by ●October 28, 20182018-10-28
Reply by ●October 28, 20182018-10-28
On Sun, 28 Oct 2018 17:46:44 -0700 (PDT), jjhudak4@gmail.com wrote:>I've considered an arduino based approach but they have >the limitations of 5V max on the input for the A/Ds and >don't want to scale it.Would 10v work for you? <https://www.ebay.com/itm/141138017533> Note the +/-15VDC power supplies. -- Jeff Liebermann jeffl@cruzio.com 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558
Reply by ●October 28, 20182018-10-28
On 29/10/18 12:33 pm, jurb6006@gmail.com wrote:>> ""youth", in quotes I'm just shy of 40" > > Wow, that explains why you're not conservative. You will be in about ten years, and don't worry, it doesn't hurt.As the saying goes... If you're not a socialist when you're young, you have no heart; If you're not a capitalist when you're old, you have no brain. :)
Reply by ●October 28, 20182018-10-28
On 10/28/2018 10:34 PM, Clifford Heath wrote:> On 29/10/18 12:33 pm, jurb6006@gmail.com wrote: >>> ""youth", in quotes I'm just shy of 40" >> >> Wow, that explains why you're not conservative. You will be in about >> ten years, and don't worry, it doesn't hurt. > > As the saying goes... > > If you're not a socialist when you're young, you have no heart; > If you're not a capitalist when you're old, you have no brain. > > :)"We must secure the existence of our people and a future for white children, because the beauty of the White Aryan woman must not perish from the Earth." The "beauty of the White Aryan woman" could stand to lose about 35 pounds on average in this country, it's way more likely to perish from heart disease than Mexicans
Reply by ●October 28, 20182018-10-28
Curves aren't going to tell you much. There isn't much variation between induvidual transistors, in the parameters that matter. Well, hopefully in circuits that are made insensitive to those parameters. Well, "high end audio", who knows. You'll have to find (or trace) the schematic and analyze it for stability and such. The headline parameters are the more important ones. Vceo (actually Vces under current, Vceo is a minimax parameter) is measured like a zener. Ic(max) is more or less where hFE falls over. hFE and Vce(sat) are measured at typical conditions (not at the same time, mind: hFE drops sharply at low Vce, for obvious reasons!). Those will more or less fix the size of the junction: hFE falls over at high current density, and junction thickness (not necessarily die thickness) sets Vceo. Junction size and thickness also set capacitance, more or less. (I don't think anyone is using super fancy doping profiles in amplifier transistors, and switchmode transistors have shit SOA so hopefully wouldn't be found here.) That leaves the biggest degree of freedom: fT or t_r and such. A ring base connection, like the ancient mesa 2N3055, has shit all fT and Vce(sat), due to large Rbb'. Modern (80s+) epitaxial are planar, made with interdigitated emitter and base, much faster. A lot of power supplies, amplifiers and such fell victim to that, where they sang like a bird after repair... To test that, set up an amplifier and measure the current gain as a function of frequency. It'd be probably a resistor from func gen to base, and collector load of a cascode (with a known faster, equally ampy) transistor. Or just a low resistance (noninductive) so Miller effect is still negligible. Switching behavior isn't quite the same because of the highly nonlinear conditions, but that's easy to test, too, just set up the right turn-on and turn-off base currents. The sharpness of turn-on/off is distinctive of different types. Also noise, but power transistors probably don't need to worry about that. If you're replacing input transistors, you may need to consider it. Testing noise figure is kind of a pain, you'll want to look up some references. Tim -- Seven Transistor Labs, LLC Electrical Engineering Consultation and Design Website: https://www.seventransistorlabs.com/ <jjhudak4@gmail.com> wrote in message news:7fe0e947-7965-45ff-bb2b-49172f9de534@googlegroups.com... I find myself in a situation where I am repairing some high end audio amps and cassette decks that have house numbered semiconductors, mainly transistors as well as JDEC p/n that are NLA. I have found a few transistors that are dead and need to be replaced. Fortunately, they are in parts of the amp where the other channel has an identical transistor. Having one transistor as a base will allow me to match something close to the original. I have made (in the past) the typical transistor curve tracer that shows the curves on a scope - cute but not precise enough for my intentions. I am more interested in a lab type instrument. Basically what I am looking for is a curve tracer that has a micro attached to it that have some A/D's on them that can record the data of interest (e.g. Ib (vb), Vce, etc. I've considered an arduino based approach but they have the limitations of 5V max on the input for the A/Ds and don't want to scale it. I've looked for old Heathkit and Tek curve tracers that I could augment with a micro but they seem to be very scarce, in addition to having transistors in them that are NLA. I could design one myself but in all honesty, I'd prefer to find something where someone has 'plowed the ground' and at the very most, I'd have to augment it with a micro. Yea, I am a bit lazy - the intent was to fix the amp, not develop a curve tracer.... Thanks in advance J
Reply by ●October 29, 20182018-10-29
On Sun, 28 Oct 2018 18:33:48 -0700 (PDT), jurb6006@gmail.com wrote:>>""youth", in quotes I'm just shy of 40 " > >Wow, that explains why you're not conservative. You will be >in about ten years, and don't worry, it doesn't hurt.Y're right. I'm just short of 71. I started out as a radical leftist, commie pinko, anti-everything, chronically protesting, hippie freak: <http://www.learnbydestroying.com/jeffl/pics/jeffl/slides/jeffl-06.html> Fast forward about 40 years, and today I'm an arch conservative, somewhat reactionary, right leaning, registered Republican, member of the establishment: <http://www.learnbydestroying.com/jeffl/pics/jeffl/slides/jeffl-08.html> It can and probably will happen to you. Resistance is futile. -- Jeff Liebermann jeffl@cruzio.com 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558
Reply by ●October 29, 20182018-10-29
On Sun, 28 Oct 2018 19:27:50 -0700, Jeff Liebermann <jeffl@cruzio.com> wrote: (...) "Simple V-I curve tracer using an oscilloscope and function generator" <https://www.youtube.com/watch?v=WWY-pakm_OM> (5:24) I recently had to match four 2N3771 power transistors in an Astron VS-35m linear power supply repair so that each transistor would overheat equally and so that the output current meter would produce sane numbers. I don't own a curve tracer, so I threw together something similar to the above video, except that the ramp (function) generator provided the current to the base, scope vertical across a small value emitter resistor, and scope horizontal to the ramp generator output. Not the best, but good enough for a quick fix. Sorry, no photos. "More Circuit Fun: Simple transistor curve tracer using Stairstep generator circuit" <https://www.youtube.com/watch?v=ZOLLoa2fH24> (11:13) <https://www.qsl.net/w2aew/youtube/curvetracer.pdf> -- Jeff Liebermann jeffl@cruzio.com 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558
Reply by ●October 29, 20182018-10-29
On 10/28/2018 11:00 PM, Jeff Liebermann wrote:> On Sun, 28 Oct 2018 18:33:48 -0700 (PDT), jurb6006@gmail.com wrote: > >>> ""youth", in quotes I'm just shy of 40" >> >> Wow, that explains why you're not conservative. You will be >> in about ten years, and don't worry, it doesn't hurt. > > Y're right. I'm just short of 71. I started out as a radical > leftist, commie pinko, anti-everything, chronically protesting, hippie > freak: > <http://www.learnbydestroying.com/jeffl/pics/jeffl/slides/jeffl-06.html> > Fast forward about 40 years, and today I'm an arch conservative, > somewhat reactionary, right leaning, registered Republican, member of > the establishment:Woah, how unusual.> <http://www.learnbydestroying.com/jeffl/pics/jeffl/slides/jeffl-08.html> > It can and probably will happen to you. Resistance is futile. > >You don't have to explain to us that the "baby boomer" generation were sellouts with no real values who'd gladly hawk their souls for ten bucks. We know, already ;-)
Reply by ●October 29, 20182018-10-29
On 10/29/2018 01:34 AM, bitrex wrote:> On 10/28/2018 11:00 PM, Jeff Liebermann wrote: >> On Sun, 28 Oct 2018 18:33:48 -0700 (PDT), jurb6006@gmail.com wrote: >> >>>> ""youth", in quotes I'm just shy of 40" >>> >>> Wow, that explains why you're not conservative. You will be >>> in about ten years, and don't worry, it doesn't hurt. >> >> Y're right. I'm just short of 71. I started out as a radical >> leftist, commie pinko, anti-everything, chronically protesting, hippie >> freak: >> <http://www.learnbydestroying.com/jeffl/pics/jeffl/slides/jeffl-06.html> >> Fast forward about 40 years, and today I'm an arch conservative, >> somewhat reactionary, right leaning, registered Republican, member of >> the establishment: > > Woah, how unusual. > >> <http://www.learnbydestroying.com/jeffl/pics/jeffl/slides/jeffl-08.html> >> It can and probably will happen to you. Resistance is futile. >> >> > > You don't have to explain to us that the "baby boomer" generation were > sellouts with no real values who'd gladly hawk their souls for ten > bucks. We know, already ;-)"Get us the funny man with the monkey! that's who we want for prez. The funny man with the monkey!!"
Reply by ●October 29, 20182018-10-29
On Monday, 29 October 2018 05:34:47 UTC, bitrex wrote:> On 10/28/2018 11:00 PM, Jeff Liebermann wrote: > > On Sun, 28 Oct 2018 18:33:48 -0700 (PDT), jurb6006@gmail.com wrote: > > > >>> ""youth", in quotes I'm just shy of 40" > >> > >> Wow, that explains why you're not conservative. You will be > >> in about ten years, and don't worry, it doesn't hurt. > > > > Y're right. I'm just short of 71. I started out as a radical > > leftist, commie pinko, anti-everything, chronically protesting, hippie > > freak: > > <http://www.learnbydestroying.com/jeffl/pics/jeffl/slides/jeffl-06.html> > > Fast forward about 40 years, and today I'm an arch conservative, > > somewhat reactionary, right leaning, registered Republican, member of > > the establishment: > > Woah, how unusual. > > > <http://www.learnbydestroying.com/jeffl/pics/jeffl/slides/jeffl-08.html> > > It can and probably will happen to you. Resistance is futile. > > > > > > You don't have to explain to us that the "baby boomer" generation were > sellouts with no real values who'd gladly hawk their souls for ten > bucks. We know, already ;-)you'll learn
