2014-04-21 00:12 nicksydney has quit [Remote host closed the connection] 2014-04-21 00:13 nicksydney has joined #qi-hardware 2014-04-21 00:43 michael_lee has joined #qi-hardware 2014-04-21 01:41 dos1 has quit [Ping timeout: 245 seconds] 2014-04-21 02:16 atommann has joined #qi-hardware 2014-04-21 02:55 wej has quit [Ping timeout: 245 seconds] 2014-04-21 03:09 wej has joined #qi-hardware 2014-04-21 03:59 5GHz? I'm still amazed and puzzled that such high frequency still can use cables at all 2014-04-21 04:01 plus the wavelength on free air is prolly short compared to the twisted pair turns-per-inch 2014-04-21 04:01 (too lazy to calculate it now) 2014-04-21 04:03 http://www.wolframalpha.com/input/?i=5GHz 60mm 2014-04-21 04:44 btw do you think file:///home/whitequark/Downloads/327216.pdf is particularly informative? 2014-04-21 04:44 :-) 2014-04-21 04:45 maybe I could deduce where to find it via html://, but I rather go have another short nap 2014-04-21 05:40 michael_lee has quit [Quit: Ex-Chat] 2014-04-21 06:15 jekhor has joined #qi-hardware 2014-04-21 07:50 dandon has joined #qi-hardware 2014-04-21 07:54 nicksydney has quit [Remote host closed the connection] 2014-04-21 08:23 sb0 has joined #qi-hardware 2014-04-21 08:30 kyak has quit [Ping timeout: 240 seconds] 2014-04-21 08:31 bartbes_ is now known as bartbes 2014-04-21 08:32 kyak has joined #qi-hardware 2014-04-21 08:32 kyak has quit [Changing host] 2014-04-21 08:32 kyak has joined #qi-hardware 2014-04-21 09:09 pcercuei has joined #qi-hardware 2014-04-21 09:13 jekhor has quit [Ping timeout: 250 seconds] 2014-04-21 09:17 so I had a look inside the faderfox 2014-04-21 09:17 everything is on a single PCB; seems they managed to find compatible COTS parts 2014-04-21 09:18 I noticed that the faderfox is no longer sold; maybe one of those parts got obsolete sending them straight back to ME hell 2014-04-21 09:19 I also noticed that the knobs on the encoders have a position indicator (which means nothing), which confirms my experience that you cannot source a small knob without an indicator 2014-04-21 09:27 and everything is encoders - no pots. I could not find a compatible pot/encoder combination... 2014-04-21 09:29 also, the search engines of component distributors are frustrating. they only let you search by petty characteristics like resistance, linear vs. log, number of taps on the resistor, etc. which are trivial to adapt to in the electronics 2014-04-21 09:29 the parameters you want is: shaft length, bushing length, body size, etc. 2014-04-21 09:40 rz2k has joined #qi-hardware 2014-04-21 09:51 and the "suggested products" in each component page often show stupid stuff like max232 or AVR ucs 2014-04-21 09:52 what I'd rather see is "encoder/pot/slider you can mount on the same PCB and it'll look good" ... 2014-04-21 09:52 nicksydney has joined #qi-hardware 2014-04-21 10:06 atommann has quit [Quit: Leaving] 2014-04-21 10:23 e.g. http://de.mouser.com/ProductDetail/ALPS/RS6011SP6003/?qs=/ha2pyFaduig0GHhvG2PgbVvcpG1OsX2nf%252bVAv/l3rE8zPJLxL0tcQ== 2014-04-21 10:24 what you want is a knob that mounts on it (which is, actually, a pain in the ass to find) - not AVR stuff, resistors, capacitors and switching regulator 2014-04-21 10:24 grrr 2014-04-21 10:27 oh, another thing I notice right now is this stupid pot went out-of-stock even though I ordered some last week 2014-04-21 10:27 10 weeks lead time now. nice! 2014-04-21 10:30 yeah, I should definitely go panel-mount 2014-04-21 10:32 yeah, most of those "parametric searches" are crap (if they have them at all) 2014-04-21 10:33 panel-mount sounds like a good choice also for ruggedness 2014-04-21 10:34 else, you could try to arrange controls in height groups and give each its own little PCB, then make a custom spacer that puts each board at the right height 2014-04-21 10:35 if something returns to the land of unobtainium, you simple redo that sub-PCB and make a new spacer 2014-04-21 10:35 and yes, such things going out of stock is a constant nuisance 2014-04-21 10:36 yeah, I'm going to go the many-PCB route 2014-04-21 10:36 or even no PCB at all, solder wire directly on the part's terminals 2014-04-21 10:37 if it can be mounted without PCB 2014-04-21 10:37 sb0: you heard of those awesome electronic poti chips that get controlled from encoder by steeping up/down the poti property in dunno 64 or 128 increments, via pulsing 2 inputs 2014-04-21 10:38 I guess you could use a encoder to pulse those stepper inputs 2014-04-21 10:38 DocScrutinizer05: i don't think he needs analog pots (in the end, it all goes to the FPGA). just something smooth and rotary 2014-04-21 10:38 the output of the analog pot needs to be digitized anyway, so using an encoder would actually simplify things a little (though such electronics problems are negligible compared to mech problems) 2014-04-21 10:38 the problem is that I need a zero position 2014-04-21 10:38 and encoders can be rotated continuously 2014-04-21 10:39 push-to-zero ? 2014-04-21 10:39 hmmm 2014-04-21 10:39 push-to-zero is a bit counterintuitive 2014-04-21 10:39 "innovative" :) 2014-04-21 10:39 not very good user experience compared to a pot that acts like an analog volume pot (as it should) 2014-04-21 10:42 well, when you could use *any* *arbitrary* poty since it's just for digitizing anyway, then I have a hard time thinking you couldn't find a single one that matches your mechanical requirements 2014-04-21 10:42 poti 2014-04-21 10:44 also it's a very common practice to place the poti on PCB and just cut the axis to length you need to exactly come out of your front plate far enough to conveniently attach a knob 2014-04-21 10:44 poti axis is available up to 15cm iirc 2014-04-21 10:45 I seen several cut poti axes in commercial devices 2014-04-21 10:46 ideally your aperture/hole in front plate is narrow and exact enough to give a sort of bearing to axis 2014-04-21 10:51 or, when your poti or encoder simply have too short axis, then there's always axis extensions to attach to the too-short axes of encoders or potis, and then cut *those* to be same length as the longer right-length ones 2014-04-21 10:53 there are even blind axis frontplate mount thingies, you could use a steel spiral spring you "plug" to their inner end, stretch the spiral spring to sufficient length and plug it to the original poti axis 2014-04-21 10:54 advantage: you have a 20% adjusting headroom by the spring, which simplifies greatly the exact ME 2014-04-21 10:57 usually you will stretch the spiral spring just so much that it is a maybe 5..10mm "too short", then the "missing" length is taken care during fixing of frontplate blind axis by elastic extension of the spring 2014-04-21 10:58 I.E. you grab the axis stub coming out of frontplate and pull the whole thing out till it is flush, then fix the nut holding the frontplate blind axis in place 2014-04-21 11:00 downside: this design has the potential to break when somebody applies too much force to it - but then otoh potis with rigid axis do as well 2014-04-21 11:00 just on this design it's only the spring that gets twisted or even breaks when you turn the know 3 turns 2014-04-21 11:01 the PCB needs to be pretty close to the front plate due to the buttons 2014-04-21 11:01 I guess the springs have a special shape of the wire they are made from 2014-04-21 11:02 (if I go the single-PCB route, but I guess I won't) 2014-04-21 11:02 oooh, so you try to find potis that are as low profile as your buttons are? well, this might turn out to be a mission impossible 2014-04-21 11:02 ideally, the pots are screwed to the front plate using their busing, too 2014-04-21 11:02 *bushing 2014-04-21 11:03 so the PCB cannot bend or break 2014-04-21 11:03 :nod: 2014-04-21 11:03 even when the knobs are handled roughly 2014-04-21 11:04 my current preferred approach is to use only that bushing 2014-04-21 11:04 for rotary pots and encoder 2014-04-21 11:04 and connect via flying wires to PCB 2014-04-21 11:05 btw a common problem with several (cheaper) builds of slider potis: they easily get damaged by user "hitting" down the slider knob and thus breaking resp damaging the resistive trace 2014-04-21 11:05 this way, I also don't give much of a crap about the body size or pin layout of whatever pot/encoder is stocked today 2014-04-21 11:05 dos1 has joined #qi-hardware 2014-04-21 11:05 they also collect dust and debris via the slot for the slider knob 2014-04-21 11:06 the slider pot is also a source of trouble right now 2014-04-21 11:06 1) hard to find a knob for it 2014-04-21 11:06 sb0: yes, that's a *very* reasonable approch for this type of device 2014-04-21 11:06 2) if I use its mounting holes, I need to put screws on the front plate 2014-04-21 11:06 thought of electronic "slider" made of sensors? 2014-04-21 11:06 could a capacitative slider be an alternative to a mechanical one ? 2014-04-21 11:07 HAH! 2014-04-21 11:07 faster! 2014-04-21 11:07 great minds think alike ;-) 2014-04-21 11:07 maybe I'll mount it on a small dedicated PCB 2014-04-21 11:07 yeah, eating breakfast and reading the news in parallel slows me down ;) 2014-04-21 11:07 to solve #2. then I'm free to use threaded spacers, possibly welded behind the front plate 2014-04-21 11:07 hmm, good idea. Time for another coffee 2014-04-21 11:08 forget welding of anything to that case 2014-04-21 11:08 (capacitive slider) not really, I want the "fader" feel like on audio tables 2014-04-21 11:08 will turn out to be a nightmare, and ruin your surface 2014-04-21 11:08 apelete has joined #qi-hardware 2014-04-21 11:09 even welding from behind? 2014-04-21 11:09 yes 2014-04-21 11:09 hmm, yeah, the weld might burn the powder coat... 2014-04-21 11:09 meh 2014-04-21 11:09 glue or snap, or forget about it 2014-04-21 11:10 is there any chance that glue will be resistant enough? 2014-04-21 11:10 probably yes 2014-04-21 11:11 even to attach spacers, which then receive screws which are mounted with some amount of torque, and then take whatever abuse the user gives to the fader? 2014-04-21 11:12 well, maybe screws in the front plate are good enough for v1 :) 2014-04-21 11:12 no, but you could weld (or whatever) the spacers to a dedicated mounting plate and then glue that plate to inside of frontplate 2014-04-21 11:12 it's not like I've been in this hell for months and I'm very fed up about it 2014-04-21 11:13 ah, yes, good idea 2014-04-21 11:13 thanks :) 2014-04-21 11:13 yw 2014-04-21 11:13 actually 2014-04-21 11:14 I won't need glue, since I could use the pots with bushing for attaching that plate 2014-04-21 11:14 it's more milling work, though 2014-04-21 11:14 to make all the holes in that plate 2014-04-21 11:15 (mounting plate) as a general rule, the more you can do in 2D, the easier. limit fancy 3D milling/molding/printing to what you strictly can't avoid. 2014-04-21 11:15 2D milling is trivial compared to 3D ;-) 2014-04-21 11:18 drilling a few holes through a stack of 50 flat mounting plates is trivial 2014-04-21 11:18 actually, I could use that plate as support for the screen's glass, too 2014-04-21 11:19 yes, you could 2014-04-21 11:19 this way I don't have to 1) find unsourcable and expensive highly-resistant thin glass (gorilla etc.) 2) mill a groove in the top surface of the case to support it 2014-04-21 11:19 so the second plate looks like a very good idea 2014-04-21 11:19 sure it is ;-D 2014-04-21 11:19 I can also adjust its height to make the knobs reach the proper position 2014-04-21 11:19 and you can make a spacer if you have to. again, cut from a board of known thickness. e.g., pre-colored acrylic 2014-04-21 11:20 in the end you may have a lot of mechanical parts but if they're all relatively painless to make, it's still easier than finding the one holy grail that solves all your problems 2014-04-21 11:21 check how commercial stuff like e.g. home stereo is doing it, thay *all* have a mounting plate and they have a frontplate to go parallel to the mountingplate 2014-04-21 11:23 yeah. direct-to-pcb is a relatively new thing and basically needs a lot of people doing almost the same thing, so it makes sense to produce lines of matching components 2014-04-21 11:23 of you need to "patch" things. e.g., buttons with intermediate knobs or the the pot-tery DocScrutinizer05 mentioned 2014-04-21 11:24 direct-to-PCB is first and foremost a cheap "trick" 2014-04-21 11:24 cheap? :) 2014-04-21 11:24 yes, it's done because for huge batches it#s cheaper than proper mounting plate design 2014-04-21 11:24 much cheaper 2014-04-21 11:31 saves a lot of manual assembly expense, and quite a number of mech components 2014-04-21 11:32 but it's flimsy and doesn't provide any proper repair-path 2014-04-21 11:32 and it's also pleasant for the designer - you control all the key parameters of your product's geometry with the layout alone 2014-04-21 11:33 (repair) toss bad pcb, insert good new one. after all, it's cheap :) 2014-04-21 11:33 exactly 2014-04-21 11:34 built to get discarded 2014-04-21 11:36 well, if you draw a graph of cost to replace and value of repair (that is, cost to replace - cost of repair - benefit of replacing old with new), you have the cost reduction not once but even twice in that formula. so if it makes sense to do the pcb approach for new items, it makes even more sense to not repair them. 2014-04-21 11:37 sure 2014-04-21 11:38 for stage proven rugged devices PCB mount isn't the design of choice anyway 2014-04-21 11:39 it's simply too shoddy for that rough treatment 2014-04-21 11:42 well, i suppose you can stabilize small PCB. they're still nice for connectivity. much easier to debug a messed-up assembly than with a ton of manually sold wires 2014-04-21 11:43 but yes, anything on which significant forces work, especially pots and such, should better not depend on the PCB for mechanical stability 2014-04-21 11:45 DocScrutinizer05: oh fuck. Ctrl+C didn't copy the proper link. http://www.usb.org/developers/whitepapers/327216.pdf 2014-04-21 11:46 s/and such/and any kind of jacks/ 2014-04-21 11:47 and pushbuttons, they should get their own small PCB with proper mech support when they are PCB type 2014-04-21 11:50 a design like (mountingscrew)____________(pushbutton)____(pushbutton)____(pushbutton)_________(mounting-screw) is usually a design gauranteed to break sooner rather than later. The PCB is not meant nor built for coping with mechanical load 2014-04-21 11:52 * whitequark reads http://hackaday.com/2014/04/21/whats-inside-a-usb-isolator/ 2014-04-21 11:52 "[Lindsay] followed [Ben Krasnow]‘s video tutorial on how to decap chips, but replaced the nitric acid with concentrated sulphuric acid, which is a bit easier to obtain." 2014-04-21 11:52 hahahaha 2014-04-21 11:52 of, the pcb flexes very nicely. and you get beautiful microfractures in the traces to examine as well :) 2014-04-21 11:52 clearly they never actually tried to obtain them 2014-04-21 11:53 any good source for slide pot knobs? 2014-04-21 11:54 whitequark: things seem to be a little weird in russia. i guess it's much easier to get a kilo of Pu than a liter of HCl ;-) 2014-04-21 11:55 * wpwrak wonders whether they have at least the decency to put the Pu in the upper shelves, out of reach of the smaller children in the supermarket 2014-04-21 11:55 wpwrak: well, Pu is definitely not considered a precursor for drugs 2014-04-21 11:55 at least not for the drugs they want to regulate 2014-04-21 11:55 so here's that 2014-04-21 11:56 hmm. it's toxic -> should make a suitable drug :) 2014-04-21 11:56 I actually wonder how hard would really be obtaining a warhead 2014-04-21 11:57 what if our military bases are about as secure as OpenSSL? that's a scary thought 2014-04-21 11:57 take two bottles and vodka and visit the next scrapyard ? 2014-04-21 11:58 that's how the jokes usually go, yes 2014-04-21 11:59 there's probably a big red button right where the head of the operator normally comes to rest when he's drunk himself into a coma again. fortunately for mankind, the contacts are too corroded to actually make contact ... 2014-04-21 12:00 one of the funniest openbsd changes in openssl lately is "remove support for big-endian i386 and x86_64" 2014-04-21 12:00 you mean funnier than the constant stream of VAX/VMS removals? 2014-04-21 12:00 seriously, it's like openssl contained United States' strategic reserve of VMS code 2014-04-21 12:01 at least VAXen are existing machines :) 2014-04-21 12:02 well, by this definition dinosarus exist too, to some degree of "existence" 2014-04-21 12:04 sb0: grmbl. soon, they'll drop support for PDP byte order too :( (PDP had mixed little and big-endian, one at the 16 bit level, the other at the 32 bit level, forgot which way it was. so 0xaabbccdd became something like { 0xcc, 0xdd, 0xaa, 0xbb }) 2014-04-21 12:05 there seem to be some people which run big-endian code in x86 2014-04-21 12:05 http://openssl.6102.n7.nabble.com/openssl-org-2789-SHA-256-bug-Big-endian-arch-td36139.html 2014-04-21 12:05 whitequark: there probably are numerous vaxen still in operation 2014-04-21 12:06 whitequark: and some of them probably doing highly mission-critical tasks. tasks too important to risk changing the platform. 2014-04-21 12:08 whitequark: e.g., there was some plant, may have been hydroelectric, in switzerland that bought old PDP-11 in the mid-1980es, for spare parts to keep their super-critical process control units running 2014-04-21 12:18 wpwrak: yes yes yes, I know, I've read an article in usenix (I think) about some atomic power plant which replaced PDP-11 with emulated PDP-11 2014-04-21 12:18 still, mission-critical infra hardly runs openssl... at least I hope so. 2014-04-21 12:19 wpwrak: which way? there's an easy way to remember. UNIX (BE) → NUXI (PDP11E) 2014-04-21 12:19 I don't think this fact will *ever* be useful in my life though 2014-04-21 12:24 ((at least I hope so)) dreamer! 2014-04-21 12:26 * DocScrutinizer05 wonders how many M80 are still running on the windows emu, using BS-M operating system 2014-04-21 12:27 then OTOH they were built til at least 1990, so prolly not EOL time for such a SIEMENS product 2014-04-21 12:27 nicksydney has quit [Remote host closed the connection] 2014-04-21 12:28 nicksydney has joined #qi-hardware 2014-04-21 12:28 IOW I'd not be surprised if you still can buy PROMEA-M in original package from SIEMENS, for maybe 10k bucks or somesuch 2014-04-21 12:30 gbraad has joined #qi-hardware 2014-04-21 12:30 gbraad has joined #qi-hardware 2014-04-21 12:31 hmmpf, at least cables ;-P https://www.google.com/search?q=PROMEA+siemens 2014-04-21 12:31 what *is* PROMEA-M? 2014-04-21 12:37 http://cache.automation.siemens.com/dnl/DM2NTUxNwAA_18320044_HB/C79000-G8076-C246_04.pdf 2014-04-21 12:38 Programmable Multi Eingabe(input)Ausgabe(output). A monster UART 2014-04-21 12:38 size of a usual contemprary PC mainboard 2014-04-21 12:39 wow, a light pen 2014-04-21 12:40 SICOMP Mxx computers 2014-04-21 12:40 http://www.tentacle.franken.de/m80/index.html 2014-04-21 12:41 I think that thing worked by synchronizing with CRT scanline start signal? 2014-04-21 12:41 xx=10..80 2014-04-21 12:41 >tentacle.franken.de 2014-04-21 12:41 right, that's how lightpens used to work 2014-04-21 12:42 simply latch the address lines of the "framebuffer" 2014-04-21 12:42 oh yes, that's much simpler 2014-04-21 12:43 how did it calibrate itself? I mean, there's afterglow of the phosphor 2014-04-21 12:44 or is CRT actually a persistence-of-vision display? 2014-04-21 12:44 sample on rising edge ? 2014-04-21 12:44 unlike e.g. oscilloscope, where it's "persistence-of-phosphor" 2014-04-21 12:44 wpwrak: right. 2014-04-21 12:47 I'm pretty sure ~50% of nuclear power plants used (or still use) SICOMP-M, and probably ~90% of powergrid infra does 2014-04-21 12:48 gbraad_ has joined #qi-hardware 2014-04-21 12:48 gbraad_ has quit [Changing host] 2014-04-21 12:48 gbraad_ has joined #qi-hardware 2014-04-21 12:48 those were dedicated process controller minicomputers 2014-04-21 12:48 (yes, they were "mini2 by the time they were new) 2014-04-21 12:49 gbraad has quit [Ping timeout: 264 seconds] 2014-04-21 12:50 traffic lights in Nuernberg/Fuerth/Erlangen been controlled by those critters, as well as Hbahn-dortmund and HBan-Duesseldorf 2014-04-21 12:50 +h 2014-04-21 12:50 I'd take SICOMP-M over some Windows machine at any time of day 2014-04-21 12:50 even today, prolly 2014-04-21 12:51 yup 2014-04-21 12:51 except for transport and energy cost ;-P 2014-04-21 12:51 then they replaced them. and thus the (lack of) punctuality of Deutsche Bahn became legend :) 2014-04-21 12:51 (250kg, ~3kW) 2014-04-21 12:52 wpwrak: something isn't punctual in germany? I refuse to believe :p 2014-04-21 12:52 (250 kg) "real computer can't be carried away" ;-) 2014-04-21 12:53 SIEMENS had an own transport branch only responsible for delivering those critters to the exact to the cm place where you needed them 2014-04-21 12:53 whitequark: apparently their train system has become a total mess after it got privatized 2014-04-21 12:54 actually it's not privatized yet 2014-04-21 12:54 wpwrak: does "total mess" mean "the timetable precision went from 30s to under 5min?" :) 2014-04-21 12:54 for punctuality, try the swiss. at train stations, there's a service announcement if a train has the temerity of being a minute late 2014-04-21 12:54 it's preparing for going stock-exchange noted 2014-04-21 12:55 and since nobody buys shares of a company that doesn't create revenue, they messed up stuff terribly during the last 10 or so years of preparing for that 2014-04-21 12:55 eugh 2014-04-21 12:56 whitequark: more like cancellations, 30-60 minutes delays on commuter transports. trains breaking down, and so on 2014-04-21 12:56 wpwrak: so like RZHD, then 2014-04-21 12:56 odd 2014-04-21 12:56 or simply whole large stations *closed* for 2 weeks due to lack of personell 2014-04-21 12:57 one dude got a flu 2014-04-21 12:57 station closed 2014-04-21 12:57 jekhor has joined #qi-hardware 2014-04-21 12:57 ROTFL 2014-04-21 12:58 and apparently also in back-office functions. e.g., i heard a story that deutsche bahn sold tickets from .de to somewhere in austria or beyond. turns out that service was cancelled for a few weeks due to construction work. so people who traveled on those tickets ended up at the last station before the construction site with nowhere to go. 2014-04-21 12:59 now the fun part: austria went out of its way to inform everybody. not only did they publish it, but they also send notifications to the other railways operators and i think they even did some ads to make sure really everybody knew. yet, ... 2014-04-21 12:59 lol, usually they provide "busersatzverkehr" 2014-04-21 13:00 dunno how they solved that. i think it was a major mountain pass or tunnel. so the detour may have been complicated. 2014-04-21 13:00 ASHPD? 2014-04-21 13:00 and you don't say austrian "officials" really were eager to inform "piefkes", eh? 2014-04-21 13:01 also, they're probably not obliged to help you if you have a ticket for a service that doesn't exist :) 2014-04-21 13:02 well, in austria I always feel like in GDR, really 2014-04-21 13:04 in general or when on the train ? 2014-04-21 13:04 alas, i can't find the story ... was a reader comment on telepolis, i think 2014-04-21 13:07 when on the highway to get out of it as ASAP, and then stopping at one of the gas stations/restaurants 2014-04-21 13:09 a donafion, a donafion!! 2014-04-21 13:10 356 2014-04-21 13:12 wpwrak: i need help in understanding this circuit http://www.electronicecircuits.com/electronic-circuits/555-negative-voltage-power-supply-circuit 2014-04-21 13:12 Service Temporarily Unavailable 2014-04-21 13:13 503 Service Temporarily Unavailable error was encountered 2014-04-21 13:13 hmm better 2014-04-21 13:13 DocScrutinizer05: huh, why do you have to leave a highway in a panic ? 2014-04-21 13:14 nicksydney: what's unclear? 2014-04-21 13:14 it says "When the output switches to ground, the C3 cap discharges through the D2 and charges the C4 capacitor to a negative voltage" ... what i'm bit confused is how C3 discharge through D2 is it through reverse bias ? 2014-04-21 13:14 (donafion) you had me wonder for a moment whether there would be hordes of beggars at gas stations in austria these days :) 2014-04-21 13:15 C3 gets charged (via D1), then when IC1:3 switches to GND level, it discharges via D2 2014-04-21 13:15 ooh, so it says exactly same as me 2014-04-21 13:16 when C3 has positive charge on IC1:3 end and gets connnected to GND, then it discharges to ground creating negative voltage on D2 2014-04-21 13:16 DocScrutinizer05: the discharging left me confused because in my mind D2 is a diode and the position of the D2 in that circuit should not allow current to flow from C3 to C4 via D2 ? 2014-04-21 13:17 well, that's exactly why it creates *negative* output voltage 2014-04-21 13:18 think of it like a tiny gnome with a mini rechargable battery charging it at V+ and then moving it to C4 to charge C4 with it, with inverted voltage with rspect to GND 2014-04-21 13:20 let me see if i get this right in my head....when PIN 3 is OFF because C3 is charged the current travels to D1 to GND while at the same time it 'pulls' current via D2 to GND which allow current to flow through C4 ? does that make sense ? 2014-04-21 13:20 http://en.wikipedia.org/wiki/Charge_pump 2014-04-21 13:21 nope, not much sense 2014-04-21 13:21 nicksydney: it want's to get to a equilibrium so it basically moves some of the negative charge at c3 to c4 2014-04-21 13:23 ok let's take one baby step at at time...... 2014-04-21 13:23 you can basically ignore everything except of C3 and C4 of the circuit 2014-04-21 13:23 nicksydney: http://wstaw.org/m/2014/04/21/plasma-desktoptH6541.png 2014-04-21 13:24 turn around the two diodes and it still works similar, just with negative output voltage 2014-04-21 13:25 nicksydney: you might have missed: NE555 is an oscilator that constantly switches pin3 between V+ and GND 2014-04-21 13:25 larsc: if you put it that way..that makes more sense to me...but since D2 is in the picture I get lost again 2014-04-21 13:25 imagine the charges to be like this: 5 |C3| -5 --- <|D2| --- 0 |C3| 0 2014-04-21 13:25 now you change the 5 on the left side to -5 2014-04-21 13:26 BZZ wrong! GND 2014-04-21 13:27 I guess what nicksydney is missing is the dynamics in the system, it oscilates 2014-04-21 13:27 you get something like this -5 |C3| -2.5 --- <|D2| --- -2.5 |C3| 0 2014-04-21 13:27 now I bet everything is claer as vacuum, larsc ;-) 2014-04-21 13:27 now i'm more lost :( 2014-04-21 13:28 thought as much ;-) 2014-04-21 13:28 ignore all that, think of a pendulum and look at http://wstaw.org/m/2014/04/21/plasma-desktoptH6541.png 2014-04-21 13:28 ok...this frickin' D2 is what confuse the hell out of me...the theory of D2 (diode) is it should conduct current in the schematics from right to left from -V it should travel to D1 ? 2014-04-21 13:29 that tiny picture shows the two phases of the oscilation process 2014-04-21 13:30 +l*3 2014-04-21 13:31 it should travel from C4 through D1 and NE555 to GND 2014-04-21 13:31 driven by charge of C3 2014-04-21 13:33 after C3 has handed over its charge to C$ via D2, the NE555 switches to other state and connects C3 to V+ again, so it charges again via v+ -> NE555:3 -> *C3* -> D1 -> GND 2014-04-21 13:33 when it's charged, NE555:3 switches to GND again 2014-04-21 13:34 nicksydney: are you clear on what charge is? 2014-04-21 13:34 so C4 -> D2 -> *C3* -> NE555:3 -> GND 2014-04-21 13:34 http://postimg.org/image/mkxeh0dcf/ 2014-04-21 13:34 NOOOO! :-) 2014-04-21 13:35 i draw up the current (1) and (2) 2014-04-21 13:35 http://wstaw.org/m/2014/04/21/plasma-desktoptH6541.png 2014-04-21 13:35 DocScrutinizer05: http://wstaw.org/m/2014/04/21/plasma-desktoptH6541.png this one shows that current does not flow via diode ... am i reading it correctly ? 2014-04-21 13:35 pin 3 never is "off" it's either connected to V+ or to GND 2014-04-21 13:36 yes 2014-04-21 13:36 DocScrutinizer05: sorry...it's GND when i say oFF :) 2014-04-21 13:36 this is an important difference though 2014-04-21 13:36 since current flows via D2 and C3 to GND 2014-04-21 13:37 C4 -> D2 -> *C3* -> NE555:3 -> GND 2014-04-21 13:38 actually lemme augment that 2014-04-21 13:38 GND -> C4 -> D2 -> *C3* -> NE555:3 -> GND 2014-04-21 13:38 DocScrutinizer05: "so C4 -> D2 -> *C3* -> NE555:3 -> GND" ... this means the even though it pass D2 and C3 no current flow through D1 ? 2014-04-21 13:38 yes 2014-04-21 13:39 current flows *either* through D1, *or* D2, for phase1 resp phase2 2014-04-21 13:41 V+ -> NE555:3 -> *C3* -> D1 -> GND **OR** GND -> C4 -> D2 -> *C3* -> NE555:3 -> GND 2014-04-21 13:41 much better :) 2014-04-21 13:42 but now i'm lost why it does not travel to D1 when "GND -> C4 -> D2 -> *C3* -> NE555:3 -> GND" 2014-04-21 13:42 _______ C3 charges _________________*OR*_____________C3 DIScharges, charging C4 2014-04-21 13:42 because the potential is lower at C3 then at GND 2014-04-21 13:43 the electrons don't want to move back to gnd 2014-04-21 13:43 larsc: correct me ...so C3 at that stage is minus which is lower than GND ? 2014-04-21 13:43 yes 2014-04-21 13:43 that's why it is called -V ;) 2014-04-21 13:43 it's minus on right end and positive on left end 2014-04-21 13:44 ahhhhhh.... 2014-04-21 13:44 since we previously charged it that way 2014-04-21 13:44 that's because the C3 is positioned with the plus near PIN 3 and minus on the other side so that's why it becomes lower than GND ? 2014-04-21 13:45 V+ -> NE555:3 -> *+C3-* -> D1 -> GND **OR** GND -> +C4- -> D2 -> *-C3+* -> NE555:3 -> GND 2014-04-21 13:45 the plus and the minus on the capacitor don't really matter for the theory behind this 2014-04-21 13:46 well, somehow it does, but it's not what's meant by the schematics sign 2014-04-21 13:46 hmmm 2014-04-21 13:46 interesting...so C3 when it's V+ is +C3- and then it's GND it become -C3+ 2014-04-21 13:47 lets go through this step by step 2014-04-21 13:47 initially the system is uncharged 2014-04-21 13:47 V+ -> NE555:3 -> *+C3-* -> D1 -> GND **OR** GND <- +*C3- <- D2 -C4+ <- GND 2014-04-21 13:47 then you apply a positive voltage on the left side of C3 2014-04-21 13:48 this creates a force and will move electrons from GND through D1 to the right side of C3 2014-04-21 13:48 V+ -> NE555:3 -> *+C3-* -> D1 -> GND **OR** GND <- NE555:3 <- +*C3- <- D2 -C4+ <- GND 2014-04-21 13:48 now you have a negative charge on the right side of D3 2014-04-21 13:48 C3 2014-04-21 13:48 clear so far? 2014-04-21 13:49 clear 2014-04-21 13:49 now you connect GND to the left side of C3 2014-04-21 13:49 which means you'll have a negative charge on both sides of C3 2014-04-21 13:49 ouch 2014-04-21 13:50 which means they'll create a opposing force 2014-04-21 13:50 ok 2014-04-21 13:50 which works on the left side of C3 2014-04-21 13:50 right side 2014-04-21 13:50 sorry 2014-04-21 13:50 found the train story :) here is the report about the problem: http://www.heise.de/tp/foren/S-Noch-ne-Bahn-Geschichte/forum-273657/msg-24689710/read/ 2014-04-21 13:50 HAH, very tricky explanation 2014-04-21 13:51 now the electrons can't move back through D1 2014-04-21 13:51 and here's some background about what they did to warn prospective travelers and other railway operators: http://www.heise.de/tp/foren/S-Re-Noch-ne-Bahn-Geschichte/forum-273657/msg-24691386/read/ 2014-04-21 13:51 but they move through D2 2014-04-21 13:51 which they will 2014-04-21 13:51 now C4 was previously uncharged 2014-04-21 13:52 since you are pushing electrons onto the top side there will be a negative charge 2014-04-21 13:52 this will continue until the forces created by the charges on C3 and C4 are in equilibirum 2014-04-21 13:52 "since you are pushing electrons onto the top side there will be a negative charge" top side of C4 ? 2014-04-21 13:52 make electrons -> holes, and I agree ;-) 2014-04-21 13:53 nicksydney: top = connected to D2 2014-04-21 13:53 rz2k has quit [] 2014-04-21 13:53 ooh, nope 2014-04-21 13:53 ok 2014-04-21 13:53 nm 2014-04-21 13:54 nicksydney: and if you switch fast enough between GND and VCC on C3 you are able to produce a constant current on -V 2014-04-21 13:54 nicksydney: yes, exactly. electrons get pushed to top of C4 by C3, via D2 2014-04-21 13:56 if you only switch once you'll have a negative potential on -V 2014-04-21 13:56 i see...that makes it easier....so the correct flow is like what DocScrutinizer05 mentioned... V+ -> NE555:3 -> *+C3-* -> D1 -> GND **OR** GND <- NE555:3 <- +*C3- <- D2 -C4+ <- GND ? 2014-04-21 13:56 yes 2014-04-21 13:56 but the potential will discharge as soon as you connect e.g. GND to -V 2014-04-21 13:58 nicksydney: note that my arrows (" <- ") are technical direction from + to -, not physical direction of electrons (from - to +) 2014-04-21 13:58 this is consistent with all usual schamtics symbols 2014-04-21 13:58 schematics 2014-04-21 14:00 DocScrutinizer05: understood 2014-04-21 14:00 so pretty much if i naively understand the whole thing is like a push and pull scenario 2014-04-21 14:00 as current flows towards the least resistance 2014-04-21 14:00 yes, exactly 2014-04-21 14:01 to understand this you need to know what voltage, current and charge is and what their relationship is 2014-04-21 14:01 larsc: i do understand that part the part that something confuses me is to understand where flows to what side....but now if i think of it as pull and push that makes it easier to understand 2014-04-21 14:02 :-) 2014-04-21 14:02 yea, I guess you can think of it as push and pull with D1 and D2 being valves 2014-04-21 14:02 first you open D1 and close D2 2014-04-21 14:02 then pull stuff in 2014-04-21 14:02 then close D1 and open D2 2014-04-21 14:02 and push stuff out 2014-04-21 14:03 hmm, for physical direction that's correct 2014-04-21 14:03 for technical direction you swap push and pull 2014-04-21 14:03 i kept on thinking that because D1 and D2 is a diode it has a breakdown voltage property which i think will not be broken as the voltage will not be that high enough 2014-04-21 14:04 DocScrutinizer05: you first pull nothing in and then push nothing out ;) 2014-04-21 14:04 sorry i meant "Reverse Voltage " 2014-04-21 14:04 less than nothing 2014-04-21 14:04 nicksydney: think of them as ideal diodes for this example 2014-04-21 14:04 actually electrons which are negative 2014-04-21 14:05 for technical pragma you push a lack of electrons out, then pull a lack of electrons in and down to GND 2014-04-21 14:06 as seen from output of 555 2014-04-21 14:06 after understanding this circuit is it wrong for me to think when reading schematics that current can flow from either direction of + and GND ? 2014-04-21 14:07 when you pull in the lack of electrons from C3, there will be more electrons on left side of C3, making the electrons on right side move to C4 2014-04-21 14:08 nicksydney: you're better off thinking about lack of electrons for reading schematics, so called "holes" 2014-04-21 14:08 it's actually those holes that move 2014-04-21 14:08 and they move the direction of the arrows in the symbols 2014-04-21 14:09 and from + to - 2014-04-21 14:09 DocScrutinizer05: "when you pull in the lack of electrons from C3, there will be more electrons on left side of C3, making the electrons on right side move to C4" this is when PIN3 is V+ ? 2014-04-21 14:09 no, this is when pin3 is connected to GND 2014-04-21 14:10 DocScrutinizer05: so this is like what larsc was saying it repels 2014-04-21 14:10 yes 2014-04-21 14:11 but I start getting confused by this comnstant switching in our convo between technical and physical pragma 2014-04-21 14:11 physical makes this so much easier ;) 2014-04-21 14:11 :) ... if you are confused than i'm 100x confused :) 2014-04-21 14:12 every sane electrician tells you that current flows from plus to minus, while they all know electrons move the opposite direction 2014-04-21 14:12 so current is "holes moving" 2014-04-21 14:13 a hole is a lack of an electron where an electron could be but isn't 2014-04-21 14:14 those holes move from plus to minus 2014-04-21 14:14 and are commonly called electric current 2014-04-21 14:14 the thing is that you have almost infinite holes 2014-04-21 14:14 larsc: I don't care 2014-04-21 14:14 neither soes nicksydney 2014-04-21 14:14 does* 2014-04-21 14:15 when I explain my water piping in my house, I don't need to consider water molecules pushing each other around 2014-04-21 14:15 same for gas pipes 2014-04-21 14:17 when i compare this circuit with other 555 circuit that uses capacitor the position of the capacitor (+/-) is what determine the negative voltage...if it is not positioned correctly it will not get negative voltage 2014-04-21 14:18 to understand how a charge pump work you can safely ignore the (+/-) signs on the capacitor and assume that it is an ideal capacitor 2014-04-21 14:19 when it's not positioned correctly, it will break - when it's a polarized capacitor. There are capacitors that have no polirization and thus no + and - side, yet they will work all the same for C3 in this circuit 2014-04-21 14:20 the + sign is connected to the side which has the bigger charge, this doesn't mean that the plus side acutally as a positive charge 2014-04-21 14:20