On Mon, 6 Feb 2023 09:32:53 -0500, Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:>On 2023-02-06 01:47, Jan Panteltje wrote: >> On a sunny day (Sun, 5 Feb 2023 16:42:49 -0500) it happened Phil Hobbs >> <pcdhSpamMeSenseless@electrooptical.net> wrote in >> <c5e52388-6aff-79e8-76d8-6e91b5f1eb29@electrooptical.net>: >> >>>>> and hang 3D printed stuff off to the side. (It all looks like DKNY >>>>> black/gold bling anyway.) >>>> >>>> SMD RF shield cans are pretty cheap too >>>> >>> >>> Yup. We use them a fair amount to control local interference, but just >>> letting a noisy wire into the box creates problems from unknown outside >>> stuff. >> >> In the old days when I did some audio design I used potcores with several windings >> making a sine oscillator to make + an - voltages from a simple 12 V or so DC input. >> I remember EPROM programmer needed a higher voltage too: >> http://panteltje.com/pub/8052AH_BASIC_computer/8052AH_BASIC_computer_inside_img_1727.jpg >> http://panteltje.com/pub/8052AH_BASIC_computer/8052AH_BASIC_computer_8049_programmer_board_img_1731.jpg >> http://panteltje.com/pub/8052AH_BASIC_computer/dc_dc_converter_detail/5V_to_30V_converter.jpg >> >> And all that is still working to this day (tested last year)! >> >> Eurocard, 100x160 mm, standard housing >> http://panteltje.com/pub/8052AH_BASIC_computer/8052AH_BASIC_computer_img_1725.jpg >> >> potcores do not radiate much. >> > >We build some things with ~ 2 MHz switchers inside, to keep the spurs >out of band. They're a pain, though, because they can do unexpected >things such as exciting unexpected PCB resonances in the hundreds of >megahertz. Hobbyist approaches such as hand-winding potcores are fun >the first couple of times, but get seriously old when you have lots of >products to support with very limited manpower. They're also physically >large, and have to be soldered manually.The LTC synchronous switchers make ghastly rings in roughly the 400 MHz range. That gets everywhere. The adorable little TPS5xxx switchers are much better, and about 1/10 the price. TPS562208 is 19 cents, but 17 volts input max. TPS54302 is 61 cents, ok for 24v in. They are 400 KHz spread-spectrum. Any time one uses a switcher it should be tested for high-frequency crud. Some include unintentional step-recovery substrate diodes. https://www.dropbox.com/s/wxorqqhj5u899bc/LM3102_SwitcherRise.JPG?raw=1> >The idea here is to make it easy for a CM or a licensee to build and >test stuff, so that we get paid without having to do all the work ourselves. > >Simon has done a lot of work on making bed-of-nails fixtures >automatically, using the Kicad board files to get the pin positions, 3D >printing to make the actual fixtures, and automatically-generated PCBs >to hold the DUT and pins and replace the rat's nest of hand wiring that >bed-of-nails testers usually have. It's really slick--he uses >standard-ish jigs from AliExpress to hold the jig, DUT, and pressure >plate, pressure pins properly distributed to keep the board straight, >the whole proverbial nine yards (*) done by a couple of Python scripts. >(He blogs about this sort of stuff periodically at <https://maskset.net>.)Is he available for hire? We've been machining them. https://www.dropbox.com/s/ljtp8kwqwun7pu2/Test_1.jpg?raw=1 https://www.dropbox.com/s/2ogmu21egve0g66/T_Sheet.jpg?raw=1> >AC wall warts aren't a solution either. Getting even vaguely enough >filtering at 120 Hz takes huge capacitors, because the inductors >required to get even two poles would be as big as the entire box.And the power diodes can snap too.> >Cheers > >Phil Hobbs > >(*) It was once thought that this originally referred to the capacity of >a cement truck in cubic yards, but it doesn't.
Rail-splitting a wall wart
Started by ●February 3, 2023
Reply by ●February 7, 20232023-02-07
Reply by ●February 7, 20232023-02-07
On Tue, 7 Feb 2023 02:48:47 -0500, Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:>On 2023-02-06 20:11, whit3rd wrote: >> On Monday, February 6, 2023 at 3:38:45 PM UTC-8, John Larkin wrote: >>> On Mon, 6 Feb 2023 15:28:31 -0800 (PST), Phil Allison >>> <palli...@gmail.com> wrote: >> >> >>>> There is no such thing as " wrong" polarity when DC plugs are fitted to leads. >>>> Some are positive tip and the rest negative. >>>> Wot planet do you live on ? >> >>> We buy DC warts that have the inner part of the barrel connector >>> positive. Negative would certainly be wrong. >> >> That's a flawed certainty. >> Here is a counterexample; the center is negative, and it isn't just >> the label, my multimeter says so too. >> >> <https://photos.app.goo.gl/7RSyQpJ4NQrKzfgu5> >> >> What's really spooky, is that I recall an identical manufacturer and part number unit >> with center positive (also correctly labelled). >> > >A P-channel FET or a series Schottky diode fixes that. I'd never omit >polarity protection from any design--even my hand-wired protos have >shunt 1N5819s or 1N5823s. > >I don't use shunt diodes in products or customer designs--in the >low-noise instruments world, it's far from unknown for people to power >24V stuff from two boat batteries in series. > >Interesting point, though--it might be a good idea to put an NFET in the >negative lead as well as a PFET in the positive one, to protect against >shorts from V- to ground. It could be a depletion device to guarantee >startup behavior. I'll think about that. > >Cheers > >Phil HobbsI generally use a polyfuse and a big unipolar TVS first thing. That handles reverse voltage and some (not all) over-voltage cases. But I'd rather have the TVS fail shorted, than blow up everything downstream. TVS shorted can be blamed on the customer! Bulletproof startup can be challenging. We hard-ground everything in our boxes and assume that a customer might want to power us from their, usually grounded, roughly 24 volt DC buss.
Reply by ●February 7, 20232023-02-07
On Tue, 07 Feb 2023 07:03:57 GMT, Jan Panteltje <alien@comet.invalid> wrote:>On a sunny day (Mon, 06 Feb 2023 07:27:00 -0800) it happened John Larkin ><jlarkin@highlandSNIPMEtechnology.com> wrote in ><5m62uhl7b3q975e5mgk2mu178nj9p7p79s@4ax.com>: > >>On Sun, 5 Feb 2023 21:11:11 -0800 (PST), Phil Allison >><pallison49@gmail.com> wrote: >> >>>John Larkin wrote: >>> >>>------------------------------ >>>> https://www.dropbox.com/s/e6okuzog0nulvjm/Rail_Splitter_B.jpg?raw=1 >>> >>> >>>** Using a AC ( transformer) wall wart has a few notable advantages it you are going to use linear regs. >>> >>>One with a single 12 volt secondary will supply +/- 16VDC or so using a ( 2 cap, 2 diode) voltage doubler. >>>Highly reliable, no SMPS noise, very safe mains isolation. >>> >>> >>>.... Phil >> >>Ac warts aren't common any more. We do try to design units that will >>work, or at least not blow up, when someone grabs the wrong cord off >>the tangle on the bench and plugs it into our box. >> >>+24DC is our default input. A box might not work at 12, but at least >>won't blow up. Warts above 24 are uncommon. >> >>I guess eventually everything will be USB-C with smart voltage >>selection. But still positive only. >> >>I guess a USB-C power source is not generally isolated. Maybe never? > >Makes no sense, its a politically [and politicians are idiots as far as science is concerned] decicion >to only allow one interfece. > >We need diversity and the optimal solution on a case by case basis. >The extra chip and possible software to make everything USB-C increases the chance of faults. > >If you want to be floating, for example because of ground loops, use transformers, potcores etc. > >Same for ever smaller, in 99 % of the cases size does not matter a lot, sometimes bigger is better, >at least you can find it back when looking for it... readable displays, useful size switches and connectors. >And if winding a transformer is too complicated for you then have those made,,, in China? > > > >USB-C is great. It's truly universal and can be mated first try in the dark. It's data line compatible with old USB connectors and provides 5 volts if you want it. I think europe is over-regulated, but the requirement that everything charge from USB-C is great. https://www.europarl.europa.eu/news/en/press-room/20220930IPR41928/long-awaited-common-charger-for-mobile-devices-will-be-a-reality-in-2024 The "Universal" serial buss is a connector and cable nightmare.
Reply by ●February 7, 20232023-02-07
On Tue, 7 Feb 2023 04:43:08 -0500, Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:>On 2023-02-06 10:25, Phil Hobbs wrote: >> On 2023-02-05 23:43, John Larkin wrote: >>> >>> https://www.dropbox.com/s/e6okuzog0nulvjm/Rail_Splitter_B.jpg?raw=1 >>> >> >> That works great in two quadrants, and has the nice feature of dumping >> most of the waste heat into the zeners, which are cheap and can work at >> high temperature.� From a belt-and-suspenders POV, it's comforting if it >> works in all four quadrants.� (These boxes don't have motors in them, >> but it's been known to happen even so.)� An extra couple of zeners would >> fix that up reasonably OK. >> >> The op amp gizmo doesn't protect against both outputs being pulled >> outwards simultaneously, but is good in four quadrants otherwise, and a >> single unipolar TVS diode on the power input fixes that.� (That would be >> a very uncommon occurrence anyway.) >> >> The main high-dissipation scenario for our stuff is if somebody shorts >> the output when it's trying to produce a large signal.� We generally >> solve that by using 22- or 33-ohm/10 uf RCs in the power leads of the >> output amp and a 2520-size 50-ohm series termination on the output. >> >> With a properly terminated load, 10V output costs 100 mA, which drops >> the positive supply by a couple of volts.� We specify +- 10V outputs, >> and generally use +-14Vish supplies, so nothing weird happens at that >> level.� The maximum dissipation in the output amp occurs at half-supply, >> where it dissipates about half a watt--not awful for a beefy part such >> as a THS3091.� (We used to use more of those, but they're getting >> expensive these days--AD8045s and THS4631s are good.� Even LM6171s are >> pretty good, if noisy, and they have thermal protection too.) > >Okay, here's one possibility. It protects against reverse polarity >warts as well as shorts to ground from either side of the wart. > >The short-circuit protection needs 5 extra parts--four FETs and one quad >pack resistor. > >(Reposting with the .asc file inline for those whose news servers don't >support text attachments.) > >Cheers > >Phil Hobbs > >Version 4 >SHEET 1 880 680 >WIRE -1584 112 -1616 112 >WIRE -1504 112 -1584 112 >WIRE -1312 112 -1408 112 >WIRE -1136 112 -1312 112 >WIRE -992 112 -1136 112 >WIRE -896 112 -992 112 >WIRE -768 112 -800 112 >WIRE -416 112 -432 112 >WIRE -1312 128 -1312 112 >WIRE -1136 128 -1136 112 >WIRE -992 128 -992 112 >WIRE -1616 144 -1616 112 >WIRE -1184 144 -1216 144 >WIRE -432 144 -432 112 >WIRE -608 192 -624 192 >WIRE -608 208 -608 192 >WIRE -192 224 -192 208 >WIRE -992 240 -992 208 >WIRE -992 240 -1184 240 >WIRE -880 240 -880 160 >WIRE -880 240 -992 240 >WIRE -384 256 -480 256 >WIRE -1616 272 -1616 224 >WIRE -1568 272 -1616 272 >WIRE -1424 272 -1424 160 >WIRE -1424 272 -1488 272 >WIRE -1360 272 -1424 272 >WIRE -1312 272 -1312 208 >WIRE -1312 272 -1360 272 >WIRE -1264 272 -1312 272 >WIRE -1216 272 -1216 144 >WIRE -1216 272 -1264 272 >WIRE -432 272 -432 224 >WIRE -1360 288 -1360 272 >WIRE -480 288 -480 256 >WIRE -464 288 -480 288 >WIRE -1312 304 -1312 272 >WIRE -1136 304 -1136 224 >WIRE -992 304 -1136 304 >WIRE -880 304 -992 304 >WIRE -384 304 -384 256 >WIRE -384 304 -400 304 >WIRE -368 304 -384 304 >WIRE -1184 320 -1184 240 >WIRE -608 320 -608 288 >WIRE -544 320 -608 320 >WIRE -464 320 -544 320 >WIRE -368 320 -368 304 >WIRE -192 320 -192 304 >WIRE -992 336 -992 304 >WIRE -608 336 -608 320 >WIRE -432 352 -432 336 >WIRE -1424 384 -1424 272 >WIRE -880 384 -880 304 >WIRE -1264 400 -1264 272 >WIRE -1232 400 -1264 400 >WIRE -1616 432 -1616 272 >WIRE -1552 432 -1616 432 >WIRE -1504 432 -1552 432 >WIRE -1312 432 -1312 384 >WIRE -1312 432 -1408 432 >WIRE -1184 432 -1184 416 >WIRE -1184 432 -1312 432 >WIRE -992 432 -992 416 >WIRE -992 432 -1184 432 >WIRE -896 432 -992 432 >WIRE -768 432 -800 432 >WIRE -608 432 -608 416 >WIRE -592 432 -608 432 >WIRE -432 448 -432 432 >WIRE -416 448 -432 448 >FLAG -1584 112 +wart >FLAG -1552 432 wartRET >FLAG -368 320 0 >FLAG -592 432 loadRet >FLAG -624 192 +Load >FLAG -1360 288 0 >FLAG -192 208 +Load >FLAG -192 320 0 >FLAG -768 112 +Load >FLAG -768 432 LoadRet >FLAG -544 320 div >FLAG -416 112 +Load >FLAG -416 448 LoadRet >SYMBOL voltage -1616 128 M0 >SYMATTR InstName V2 >SYMATTR Value 24 >SYMBOL res -624 192 R0 >SYMATTR InstName R1 >SYMATTR Value 10k >SYMBOL res -624 320 R0 >SYMATTR InstName R2 >SYMATTR Value 6k >SYMBOL Opamps\\UniversalOpamp2 -432 304 R0 >WINDOW 0 74 -39 Left 2 >WINDOW 39 28 51 Left 2 >SYMATTR InstName U1 >SYMATTR SpiceLine Ilimit=1.5A >SYMATTR Value2 Avol=1Meg GBW=1.5Meg Slew=1Meg >SYMATTR SpiceLine2 Rail=0 Vos=0 En=0 Enk=0 In=0 Ink=0 Rin=500Meg >SYMBOL res -176 208 M0 >SYMATTR InstName R10 >SYMATTR Value 20 >SYMBOL pmos -800 160 M270 >WINDOW 0 16 -37 VRight 2 >WINDOW 3 -28 -28 VRight 2 >SYMATTR InstName q1 >SYMATTR Value AO6407 >SYMBOL nmos -800 384 R90 >WINDOW 0 -10 133 VLeft 2 >WINDOW 3 -23 57 VLeft 2 >SYMATTR InstName Q4 >SYMATTR Value AP9465GEM >SYMBOL res -1472 256 R90 >WINDOW 0 0 56 VBottom 2 >WINDOW 3 32 56 VTop 2 >SYMATTR InstName R7 >SYMATTR Value {Rshort} >SYMBOL res -416 128 M0 >SYMATTR InstName R5 >SYMATTR Value 1m >SYMBOL res -416 336 M0 >SYMATTR InstName R6 >SYMATTR Value 1m >SYMBOL res -1008 112 R0 >SYMATTR InstName R4.3 >SYMATTR Value 10k >SYMBOL res -976 320 M0 >SYMATTR InstName R4.4 >SYMATTR Value 10k >SYMBOL nmos -1232 320 R0 >SYMATTR InstName M1 >SYMATTR Value 2N7002 >SYMBOL pmos -1184 224 M180 >SYMATTR InstName M2 >SYMATTR Value BSS84 >SYMBOL res -1328 112 R0 >SYMATTR InstName R4.1 >SYMATTR Value 10k >SYMBOL res -1296 288 M0 >WINDOW 3 30 109 Left 2 >SYMATTR Value 10k >SYMATTR InstName R4.2 >SYMBOL pmos -1504 160 R270 >WINDOW 0 16 -37 VRight 2 >WINDOW 3 -28 -28 VRight 2 >SYMATTR InstName q2 >SYMATTR Value AO6407 >SYMBOL nmos -1504 384 M90 >WINDOW 0 -17 54 VLeft 2 >WINDOW 3 70 124 VLeft 2 >SYMATTR InstName Q3 >SYMATTR Value AP9465GEM >TEXT -136 376 Left 2 !.tran 1m >TEXT -416 208 Left 2 ;Behavioral\nTCA0372 >TEXT -136 400 Left 2 !.param Rshort 1m\n.step param Rshort list 1meg 100m >TEXT -56 88 Left 2 ;Wall Wart Polarity and\nShort Circuit Protection\n >\nP. Hobbs, 2023-02-07That's kinda complex for my taste. My zeners do reverse polarity protection, with a polyfuse or such to limit current. Most warts current limit pretty well, cw or burp mode. I'd love a fast 2-terminal current limiter device with thermal shutdown. We've tried some ic e-fuse parts which liked to blow up. TCA0372 is supposed to thermal limit but it doesn't always.
Reply by ●February 7, 20232023-02-07
On a sunny day (Tue, 07 Feb 2023 09:41:50 -0800) it happened John Larkin <jlarkin@highlandSNIPMEtechnology.com> wrote in <8v25uh57g2p2il0gcb6chtfc5odrdgvlas@4ax.com>:>USB-C is great. It's truly universal and can be mated first try in the >dark. It's data line compatible with old USB connectors and provides 5 >volts if you want it.USB-C sucks, my smartphone has it and already one time I did not put the connector in far enough and it had not charged. Its too small for real power, how many times can you put that stuff in? I already had an other problem with a normal USB cable just hours ago. Oh and again yesterday with a USB hub that had switched off ports.. OK it is all intensively used, but even your phone is plugged in for charging on a daily bases, so 365 times a year. Mechanical wear.. electrical damage / burn in to contacts ..what not I was thinking about wireless charging but that sucks too as it causes even more RF .. We really need fusion powered eternal batteries and fusion powered cars. Wallwarts are OK, I have some big ones for LED strips for room lighting. The small ones I have from Reichelt have a switch to select the voltage and came with a bunch of adaptors but you can put those in + / - reversed. http://panteltje.com/pub/universal_wart_IXIMG_0879.JPG So use a bridge rectifier in your gadget, should be OK.
Reply by ●February 7, 20232023-02-07
On 2023-02-07 12:54, John Larkin wrote:> On Tue, 7 Feb 2023 04:43:08 -0500, Phil Hobbs > <pcdhSpamMeSenseless@electrooptical.net> wrote: > >> On 2023-02-06 10:25, Phil Hobbs wrote: >>> On 2023-02-05 23:43, John Larkin wrote: >>>> >>>> https://www.dropbox.com/s/e6okuzog0nulvjm/Rail_Splitter_B.jpg?raw=1 >>>> >>> >>> That works great in two quadrants, and has the nice feature of dumping >>> most of the waste heat into the zeners, which are cheap and can work at >>> high temperature. From a belt-and-suspenders POV, it's comforting if it >>> works in all four quadrants. (These boxes don't have motors in them, >>> but it's been known to happen even so.) An extra couple of zeners would >>> fix that up reasonably OK. >>> >>> The op amp gizmo doesn't protect against both outputs being pulled >>> outwards simultaneously, but is good in four quadrants otherwise, and a >>> single unipolar TVS diode on the power input fixes that. (That would be >>> a very uncommon occurrence anyway.) >>> >>> The main high-dissipation scenario for our stuff is if somebody shorts >>> the output when it's trying to produce a large signal. We generally >>> solve that by using 22- or 33-ohm/10 uf RCs in the power leads of the >>> output amp and a 2520-size 50-ohm series termination on the output. >>> >>> With a properly terminated load, 10V output costs 100 mA, which drops >>> the positive supply by a couple of volts. We specify +- 10V outputs, >>> and generally use +-14Vish supplies, so nothing weird happens at that >>> level. The maximum dissipation in the output amp occurs at half-supply, >>> where it dissipates about half a watt--not awful for a beefy part such >>> as a THS3091. (We used to use more of those, but they're getting >>> expensive these days--AD8045s and THS4631s are good. Even LM6171s are >>> pretty good, if noisy, and they have thermal protection too.) >> >> Okay, here's one possibility. It protects against reverse polarity >> warts as well as shorts to ground from either side of the wart. >> >> The short-circuit protection needs 5 extra parts--four FETs and one quad >> pack resistor. >> >> (Reposting with the .asc file inline for those whose news servers don't >> support text attachments.) >> >> Cheers >> >> Phil Hobbs >> >> Version 4 >> SHEET 1 880 680<snip>> > That's kinda complex for my taste. My zeners do reverse polarity > protection, with a polyfuse or such to limit current. Most warts > current limit pretty well, cw or burp mode.My threat model includes: 1. Reverse polarity wart 2. Either side of the wart shorted to ground, normal otherwise 3. Either side shorted to ground, reversed. I have customers who like to use huge boat/RV batteries to power low-noise test setups, and I have occasionally been guilty of siamesing one wall wart into two boxes, so I assume others are too. The NFET/PFET thing turns off both sides, so no damage or weird behavior should occur. An extra five tiny parts to do all that isn't bad, I don't think. (All the FETs can be SC-70s, probably.)> I'd love a fast 2-terminal current limiter device with thermal > shutdown. We've tried some ic e-fuse parts which liked to blow up. > > TCA0372 is supposed to thermal limit but it doesn't always.Well, with way over an amp worth of output and a small thermal mass, I can easily believe you might melt an output device before the thermal limiter knew about it. Unlikely to be an issue in this case because of the series-terminated outputs. 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 ●February 7, 20232023-02-07
On 2023-02-07 12:35, John Larkin wrote:> On Tue, 7 Feb 2023 02:48:47 -0500, Phil Hobbs > <pcdhSpamMeSenseless@electrooptical.net> wrote: > >> On 2023-02-06 20:11, whit3rd wrote: >>> On Monday, February 6, 2023 at 3:38:45 PM UTC-8, John Larkin wrote: >>>> On Mon, 6 Feb 2023 15:28:31 -0800 (PST), Phil Allison >>>> <palli...@gmail.com> wrote: >>> >>> >>>>> There is no such thing as " wrong" polarity when DC plugs are fitted to leads. >>>>> Some are positive tip and the rest negative. >>>>> Wot planet do you live on ? >>> >>>> We buy DC warts that have the inner part of the barrel connector >>>> positive. Negative would certainly be wrong. >>> >>> That's a flawed certainty. >>> Here is a counterexample; the center is negative, and it isn't just >>> the label, my multimeter says so too. >>> >>> <https://photos.app.goo.gl/7RSyQpJ4NQrKzfgu5> >>> >>> What's really spooky, is that I recall an identical manufacturer and part number unit >>> with center positive (also correctly labelled). >>> >> >> A P-channel FET or a series Schottky diode fixes that. I'd never omit >> polarity protection from any design--even my hand-wired protos have >> shunt 1N5819s or 1N5823s. >> >> I don't use shunt diodes in products or customer designs--in the >> low-noise instruments world, it's far from unknown for people to power >> 24V stuff from two boat batteries in series. >> >> Interesting point, though--it might be a good idea to put an NFET in the >> negative lead as well as a PFET in the positive one, to protect against >> shorts from V- to ground. It could be a depletion device to guarantee >> startup behavior. I'll think about that. >>> I generally use a polyfuse and a big unipolar TVS first thing. That > handles reverse voltage and some (not all) over-voltage cases. But I'd > rather have the TVS fail shorted, than blow up everything downstream. > > TVS shorted can be blamed on the customer! > > Bulletproof startup can be challenging. > > We hard-ground everything in our boxes and assume that a customer > might want to power us from their, usually grounded, roughly 24 volt > DC buss.We often do that too, and used to do it more when we could still get PolyZens, which were a wonderfully complete and compact solution (*sniff* *sniff*). A big TVS can desolder itself and fall off the board if the PCB is vertical. Most of our stuff has switchers and lots of filtering, and so runs fine off a common power buss. The rail splitter thing is for light-duty use. 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 ●February 7, 20232023-02-07
On 07/02/2023 6:01 pm, Jan Panteltje wrote:> On a sunny day (Tue, 07 Feb 2023 09:41:50 -0800) it happened John Larkin > <jlarkin@highlandSNIPMEtechnology.com> wrote in > <8v25uh57g2p2il0gcb6chtfc5odrdgvlas@4ax.com>: > >> USB-C is great. It's truly universal and can be mated first try in the >> dark. It's data line compatible with old USB connectors and provides 5 >> volts if you want it. > > USB-C sucks, my smartphone has it and already one time I did not put the connector > in far enough and it had not charged. > Its too small for real power, how many times can you put that stuff in? > I already had an other problem with a normal USB cable just hours ago. > Oh and again yesterday with a USB hub that had switched off ports.. > OK it is all intensively used, but even your phone is plugged in > for charging on a daily bases, so 365 times a year. > Mechanical wear.. electrical damage / burn in to contacts ..what not > I was thinking about wireless charging but that sucks too as it causes even more RF .. > We really need fusion powered eternal batteries and fusion powered cars. > > Wallwarts are OK, I have some big ones for LED strips for room lighting. > The small ones I have from Reichelt have a switch to select the voltage > and came with a bunch of adaptors but you can put those in + / - reversed. > http://panteltje.com/pub/universal_wart_IXIMG_0879.JPG > So use a bridge rectifier in your gadget, should be OK. > > >USB-C has 24 pins on 0.5mm pitch on something that rattles around in overcoat pockets and handbags. Sure sounds like great recipe for robust and reliable contact </sarcasm> piglet
Reply by ●February 7, 20232023-02-07
On 2/6/2023 10:36 PM, Phil Allison wrote:> bitrex wrote: > =============== >> On 2/6/2023 8:24 PM, Phil Allison wrote: >> >>> >>> ** Most customers ( or consumers ) know to use ONLY the wall wart that came packed with the item they bought. >>> Only IDIOTS think you can "plug and play" with such items. >>> >>> That JL claims to deal with idiots on a regular basis surprises me not. >>> >>> >>> ...... Phil >>> >> I also thought he didn't deal with musicians and didn't even like music! >> >> Here's the power supply section of a Korg MS2000 synthesizer, I worked >> on one one time that somebody had plugged an AC adapter of unknown type >> into, as I recall the list of fucked components was long, some bits like >> the SMT input filter and diode were rattling around in the enclosure, F1 >> was done, IC15 was done, FU1 was open, fortunately no damage to the CPU >> or DSP though. > > ** Long time ago, I was sent a Korg analog synth for repair that was the *victim* of a main power accident. > A faulty ( home made ) extension lead had exploded a 12 inch length of ground track on the PCB along with a cup full of ICs, tantalum caps, diodes etc. Took quite some time, but I eventually fixed it. > I remember the young owner was grumpy about the fee. > > ...... Phil > >I don't usually repair things professionally (probably a good idea), so this one I ended up keeping for myself once it was running again. I bought it off a friend's buddy for $50 in unknown condition other than no power-up. Sounds like you had to rebuild most of the internal power supply-bits, in the case of this later all-digital Korg product in the interest of expedience I replaced what I could get easily enough from Mouser and then just carefully bypassed the blown 3.3 volt buck, and bodged in one of these: <https://www.pololu.com/product/2830> with the shutdown pin connected appropriately and it works OK. I expect some fashion of hypothetical client out there would be unhappy with that as it would then not be "original" (maybe the same type that would be unhappy if I'd charged what it cost to ensure it was.) But I didn't really feel like messing with 3rd party vendors selling discontinued buck controller ICs of unknown provenance and hope for the best...
Reply by ●February 7, 20232023-02-07
On 2/7/2023 12:35 PM, John Larkin wrote:> On Tue, 7 Feb 2023 02:48:47 -0500, Phil Hobbs > <pcdhSpamMeSenseless@electrooptical.net> wrote: > >> On 2023-02-06 20:11, whit3rd wrote: >>> On Monday, February 6, 2023 at 3:38:45 PM UTC-8, John Larkin wrote: >>>> On Mon, 6 Feb 2023 15:28:31 -0800 (PST), Phil Allison >>>> <palli...@gmail.com> wrote: >>> >>> >>>>> There is no such thing as " wrong" polarity when DC plugs are fitted to leads. >>>>> Some are positive tip and the rest negative. >>>>> Wot planet do you live on ? >>> >>>> We buy DC warts that have the inner part of the barrel connector >>>> positive. Negative would certainly be wrong. >>> >>> That's a flawed certainty. >>> Here is a counterexample; the center is negative, and it isn't just >>> the label, my multimeter says so too. >>> >>> <https://photos.app.goo.gl/7RSyQpJ4NQrKzfgu5> >>> >>> What's really spooky, is that I recall an identical manufacturer and part number unit >>> with center positive (also correctly labelled). >>> >> >> A P-channel FET or a series Schottky diode fixes that. I'd never omit >> polarity protection from any design--even my hand-wired protos have >> shunt 1N5819s or 1N5823s. >> >> I don't use shunt diodes in products or customer designs--in the >> low-noise instruments world, it's far from unknown for people to power >> 24V stuff from two boat batteries in series. >> >> Interesting point, though--it might be a good idea to put an NFET in the >> negative lead as well as a PFET in the positive one, to protect against >> shorts from V- to ground. It could be a depletion device to guarantee >> startup behavior. I'll think about that. >> >> Cheers >> >> Phil Hobbs > > I generally use a polyfuse and a big unipolar TVS first thing. That > handles reverse voltage and some (not all) over-voltage cases. But I'd > rather have the TVS fail shorted, than blow up everything downstream. > > TVS shorted can be blamed on the customer! > > Bulletproof startup can be challenging.Sounds like an application for an SPLD with analog comparators and state machine, e.g. <https://www.mouser.com/datasheet/2/698/SLG46537r106_05242017_1141056-2956193.pdf> They're about 50 cents in quantity programmed. 8 states seems like enough to build a little fault tree that could quickly determine the most common disallowed states (over or under-voltage, reverse polarity, AC plugged in instead of DC) and respond appropriately> We hard-ground everything in our boxes and assume that a customer > might want to power us from their, usually grounded, roughly 24 volt > DC buss. >
