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Path: ...!eternal-september.org!feeder2.eternal-september.org!news.eternal-september.org!.POSTED!not-for-mail From: Bill Sloman <bill.sloman@ieee.org> Newsgroups: sci.electronics.design Subject: Re: Curve Tracers Date: Sat, 23 Nov 2024 15:04:32 +1100 Organization: A noiseless patient Spider Lines: 164 Message-ID: <vhrk8s$1io5t$1@dont-email.me> References: <vhkhcg$2ip8$2@dont-email.me> <o50sjjpmjmrdbvs9po8inhcdn961a0923g@4ax.com> <vhl842$70jp$1@dont-email.me> <d5hsjj967gqpgmoja3ndgi5re9o38p3ki5@4ax.com> <vhlt6a$9hat$3@dont-email.me> <j10tjjt05qolld20qtpfpg2nmb1vhcpsrt@4ax.com> <vhn7gk$kdip$1@dont-email.me> <v6mujjtghinmo0gf279taqv4osv63b7ir2@4ax.com> <vhog3g$rlc2$1@dont-email.me> <09hvjjta6p3t9ffe2ji2j30hnautcvdmqa@4ax.com> <vhqhfo$19b0h$3@dont-email.me> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Injection-Date: Sat, 23 Nov 2024 05:04:45 +0100 (CET) Injection-Info: dont-email.me; posting-host="6a0cf29e5f00b75ac96a859d22691f04"; logging-data="1663165"; mail-complaints-to="abuse@eternal-september.org"; posting-account="U2FsdGVkX19s6oQ1VxuhNYzRHXRBOd17+Eb1JSuYZ+o=" User-Agent: Mozilla Thunderbird Cancel-Lock: sha1:ls3J0XgnTSmXQ2z006QU7UehC3k= X-Antivirus-Status: Clean Content-Language: en-US X-Antivirus: Norton (VPS 241122-4, 23/11/2024), Outbound message In-Reply-To: <vhqhfo$19b0h$3@dont-email.me> Bytes: 8595 On 23/11/2024 5:11 am, Cursitor Doom wrote: > On Thu, 21 Nov 2024 15:43:21 -0800, john larkin wrote: > >> On Thu, 21 Nov 2024 23:35:13 -0000 (UTC), Cursitor Doom >> <cd999666@notformail.com> wrote: >> >>> On Thu, 21 Nov 2024 08:03:00 -0800, john larkin wrote: >>> >>>> On Thu, 21 Nov 2024 12:02:28 -0000 (UTC), Cursitor Doom >>>> <cd999666@notformail.com> wrote: >>>> >>>>> On Wed, 20 Nov 2024 16:37:39 -0800, john larkin wrote: >>>>> >>>>>> On Thu, 21 Nov 2024 00:00:10 -0000 (UTC), Cursitor Doom >>>>>> <cd999666@notformail.com> wrote: >>>>>> >>>>>>> On Wed, 20 Nov 2024 12:27:04 -0800, john larkin wrote: >>>>>>> >>>>>>>> On Wed, 20 Nov 2024 18:00:34 -0000 (UTC), Cursitor Doom >>>>>>>> <cd999666@notformail.com> wrote: >>>>>>>> >>>>>>>>> On Wed, 20 Nov 2024 07:40:08 -0800, john larkin wrote: >>>>>>>>> >>>>>>>>>> On Wed, 20 Nov 2024 11:32:32 -0000 (UTC), Cursitor Doom >>>>>>>>>> <cd999666@notformail.com> wrote: >>>>>>>>>> >>>>>>>>>>> Gentlemen, >>>>>>>>>>> >>>>>>>>>>> Curve tracers reveal useful info about the dynamic >>>>>>>>>>> characteristics of semiconductors and make designing for same >>>>>>>>>>> much more predictable and dependable than relying on spice >>>>>>>>>>> models and simulation alone. But they're typically rare beasts >>>>>>>>>>> and expensive to come by and boat anchor varieties are seriously >>>>>>>>>>> heavy and bulky. >>>>>>>>>>> I think therefore that a curve tracer would make an excellent >>>>>>>>>>> project, >>>>>>>>>>> using the X&Y inputs of a scope as the display. Has anyone here >>>>>>>>>>> attempted this? I'd be interested to know what the main >>>>>>>>>>> challenges are likely to be. >>>>>>>>>>> >>>>>>>>>>> -CD >>>>>>>>>> >>>>>>>>>> I've considered it. It would be much more valuable if it traced >>>>>>>>>> capacitances too. >>>>>>>>> >>>>>>>>> A VNA is best for that. I've been using my big HP one this >>>>>>>>> afternoon to label some random bunches of caps and inductors whose >>>>>>>>> values I couldn't read. Trouble is, there doesn't seem to be much >>>>>>>>> agreement on what frequency to test these devices at. I've heard >>>>>>>>> 100khz, 1Mhz, >>>>>>>>> 10Mhz and 100Mhz mentioned from different sources. I'm pretty sure >>>>>>>>> the 100Mhz testing is for RF specified devices only, though. From >>>>>>>>> what I've seen, there's no reliable alternative to testing each >>>>>>>>> batch for oneself, because (certainly with ancient NOS leaded (as >>>>>>>>> in non-SMD) stock) you have no idea what frequency the factory >>>>>>>>> tested them at and different manufacturers in different countries >>>>>>>>> at different times used different methods! >>>>>>>> >>>>>>>> What I want is C-V curves. I guess a VNA can do that with a some >>>>>>>> bias tees and various power supplies. >>>>>>> >>>>>>> If you only want C/V curves, what's wrong with a plain 'scope and a >>>>>>> pulse generator? >>>>>> >>>>>> How would you do that? >>>>> >>>>> Ah! Well, I obviously mis-read your earlier statement. My bad, soz. >>>>> >>>>>>>>>> The display should be on a computer and the data archived. >>>>>>>>> >>>>>>>>> For people such as yourself, certainly. For me as a hobbyist, a >>>>>>>>> CRT is fine. >>>>>>>> >>>>>>>> You have to read the analog screen and write down numbers. Or take >>>>>>>> a picture. >>>>>>> >>>>>>> It would only be a (slight) issue if I needed to share an image with >>>>>>> a third party. Aside from that, there's nothing I couldn't live >>>>>>> with. You're obviously requiring more than that, though. >>>>>>> >>>>>>>>>> I often just set up a breadboard and test parts. Last week I >>>>>>>>>> blew out some power mosfet gates. Some have internal zeners; >>>>>>>>>> this one doesn't. >>>>>>>>> >>>>>>>>> I can kill a MOSFET at 50' just by looking at it (certainly in >>>>>>>>> winter). In fact I shock myself from all the static I build up and >>>>>>>>> it ain't funny. Having dry skin is great for when I touch HV by >>>>>>>>> accident (happens quite a lot) but the flip side is I accumulate >>>>>>>>> and hold static charge like no one else I know. >>>>>>>> >>>>>>>> Some fets have protective gate zeners. They typically clamp at >>>>>>>> +-40 volts. >>>>>>>> >>>>>>>> Here in San Francisco, we never get static zapped. High humidity. >>>>>>> >>>>>>> So you never need to wear a wrist/earth strap? That's a big plus. I >>>>>>> find them *so* restrictive and irritating when they (invariably) >>>>>>> catch on something. >>>>>>> >>>>>>>>>> Most mosfets drain avalanche, but the voltage is never >>>>>>>>>> specified, in fact deliberately hidden. I have to measure that. >>>>>>>>>> A good curve tracer should measure that too. >>>>>>>>>> >>>>>>>>>> Currents should go down to picoamps. >>>>>>>>>> >>>>>>>>>> The fact that there aren't many curve tracers for sale suggests >>>>>>>>>> a small market. >>>>>>>>> >>>>>>>>> But a market, though small perhaps, there must be. >>>>>>>> >>>>>>>> Sure. It would be a fun project. >>>>>>> >>>>>>> And with thanks to Trump's tariffs, you might even make a few buxx >>>>>>> out of it, too. >>>>>> >>>>>> Is there going to be tariffs on USB capacitance-measuring curve >>>>>> tracers? >>>>> >>>>> Not specifically, but I imagine Trump will want tariffs on Chinese >>>>> imports in general, which should give some breathing space profit-wise >>>>> to US manufacturers. >>>>> I have to say I do admire Trump's job creation ideas, which should >>>>> produce solid results, as opposed to old Joe's approach of destroying >>>>> US jobs, seemingly on purpose. I say old Joe's approach, but what I >>>>> really mean is the approach of the Globalists who tell him and his ilk >>>>> what to do. >>>> >>>> We should stop paying the Chinese for the shipping costs of cheap >>>> junk, >>>> for starters. >>> >>> The US does that too?? Wow. I thought that was just a European thing. >> >> The Chinese are a "disadvantaged country" per the International Postal >> Union. > > That needs updating! > >> They will ship a cheap ebay thing here for free. It would cost me a >> bundle to ship it back. > > Same here. Function generator arrived today direct from China and I didn't > have to pay a penny in sales tax for it. No duties whatsoever. Express > postage was free, too. The treasuries of Europe must be losing untold tens > of billions in taxes due to this. And yet everyone has to pay sales tax on > domestically-produced goods! It's madness on steroids. They'll probably > claim it would cost more to collect the tax than the revenue doing so > would generate, but that's indefensible BS plain and simple. Inventing what you imagine will be their response and describing that imagined response as "indefensible BS plain and simple" is a pretty obvious example of indefensible BS. If they were to conform to your prediction, then you would have been right, but a prophet you aren't up to much. Kamala Harris didn't win the recent US election, not matter how much your imaginary globalists might have like her too. -- Bill Sloman, Sydney -- Bil Sloman, Sydney