whit3rd wrote: ----------------------> 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>** 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
Rail-splitting a wall wart
Started by ●February 3, 2023
Reply by ●February 6, 20232023-02-06
Reply by ●February 6, 20232023-02-06
On 2/6/2023 8:24 PM, Phil Allison wrote:> whit3rd wrote: > ---------------------- >> 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> > > > ** 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. <https://imgur.com/a/Vi0as26>
Reply by ●February 6, 20232023-02-06
On Monday, February 6, 2023 at 5:24:49 PM UTC-8, palli...@gmail.com 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.Oh, I swap power supplies freely, but there's the small matter of reverse-engineering the connections beforehand. There's some amusing moments: lots of 13V zeners burn up fuses protecting CD/HD external drives. The +12 for those drives tolerates lots of overvoltage, the zeners and fuses were overkill, and axed perfectly functional (but loose specification) power. My Samsung television from the thrift store works fine with the right Dell power brick. There's likely never to be a Samsung power brick next to such an item...
Reply by ●February 6, 20232023-02-06
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
Reply by ●February 7, 20232023-02-07
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?
Reply by ●February 7, 20232023-02-07
On a sunny day (Mon, 6 Feb 2023 09:32:53 -0500) it happened Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote in <d93efa31-613a-c9ff-ef1d-f9f13267a75a@electrooptical.net>:>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.But never fail! Little EI core PMT supply: http://panteltje.com/pub/PMT_HV_supply_with_regulator_img_3175.jpg http://www.panteltje.com/pub/PMT_regulated_power_supply_diagram_img_3182.jpg still working!>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.Yes all depends on quantity, I wind such a core in a few minutes...>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>.)Interesting site, it loops back to you too..>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. > >CheersThe PMT thing above runs on 4 AA Eneloops cells inside and controlled by this box: http://panteltje.com/pub/gamma_spectrometer_plus_probe_plus_geiger_counter_2_IMG_4185.JPG the PMT itself and that HV generator, input stage and scintillation crystal are in the cardboard tube. The spectrum analyzer and control are in the alu box.. That little box is just a Geiger counter with RS232 interface running from a 12V wallwart logging to a Raspberry Pi, it uses an old army surplus geiger tube. As to transformers, and now I trigger John L. on 'out of spec' in my other geiger counter I make the HV by using a standard 1:10 audio output transformer in reverse: http://panteltje.com/panteltje/pic/gm_pic2/ scroll down to circuit diagram... Also been working fine now for many years... So not always 'winding' is needed. But not sure it is in that audio transformer flashover spec... :-)
Reply by ●February 7, 20232023-02-07
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 -- 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
This is a multi-part message in MIME format. --------------8B2DB46CD4D12C50B6533965 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit 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. (I'll post it again with the .asc file inline for those whose news servers don't support text attachments.) 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 --------------8B2DB46CD4D12C50B6533965 Content-Type: text/plain; charset=UTF-8; name="railsplitProtection.asc" Content-Transfer-Encoding: base64 Content-Disposition: attachment; filename="railsplitProtection.asc" VmVyc2lvbiA0ClNIRUVUIDEgODgwIDY4MApXSVJFIC0xNTg0IDExMiAtMTYxNiAxMTIKV0lS RSAtMTUwNCAxMTIgLTE1ODQgMTEyCldJUkUgLTEzMTIgMTEyIC0xNDA4IDExMgpXSVJFIC0x MTM2IDExMiAtMTMxMiAxMTIKV0lSRSAtOTkyIDExMiAtMTEzNiAxMTIKV0lSRSAtODk2IDEx MiAtOTkyIDExMgpXSVJFIC03NjggMTEyIC04MDAgMTEyCldJUkUgLTQxNiAxMTIgLTQzMiAx MTIKV0lSRSAtMTMxMiAxMjggLTEzMTIgMTEyCldJUkUgLTExMzYgMTI4IC0xMTM2IDExMgpX SVJFIC05OTIgMTI4IC05OTIgMTEyCldJUkUgLTE2MTYgMTQ0IC0xNjE2IDExMgpXSVJFIC0x MTg0IDE0NCAtMTIxNiAxNDQKV0lSRSAtNDMyIDE0NCAtNDMyIDExMgpXSVJFIC02MDggMTky 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Reply by ●February 7, 20232023-02-07
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, 2023-02-07 -- 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 04:41, Phil Hobbs wrote: <snip>> > 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. > > (I'll post it again with the .asc file inline for those whose news > servers don't support text attachments.) >I should add that there's nothing special about the choice of FETs--they're just what came up in the LTspice library dialog. Obviously things like ESD protection capacitors are missing as well--probably 1 uF ceramic from each side of the wart to ground. 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
