Who is on crack? Me or the chinese DMM? - Page 1
Forum section: electronics / beginners

author: raspberrypi
author_rank: Frequent Contributor
timestamp: March 31, 2017, 09:44:25 pm
content: Or am I just blind. I have a variable DC supply plugged into a simple little circuit that uses two resistors a light sensitive cell( changes resistance when its under light), and an NPN to light up some little ada fruit black light LED.Am I not seeing the meter right, it looks like my circuit is pulling 5.5 AMPS! Volts is on the left in parallel with + and -, amps is on the right hooked up between the + of the supply and the + of the light dimmer circuit. These meters kind of suck because they have no auto range circuit, but costs 8 bucks so I can't really complain. What am I doing wrong? When I put the meter on milliamps it doesn't display since they didn't make the display say OL its hard to tell if you are not hooked up or you are but you are above the range.

author: Avacee
author_rank: Unknown
timestamp: March 31, 2017, 10:01:44 pm
content: The amps range is set to 20mA and you are plugged into the mA socket - looks like you are drawing 5.5mA, 0.05mA and 6.5mA

author: CatalinaWOW
author_rank: Super Contributor
timestamp: March 31, 2017, 10:06:22 pm
content: I couldn't see the difference in hookups or setups in the three pictures, but all appear to be displaying a potentially reasonable current. 5.5 milliamps in the first, 0.05 milliamps in the second and 6.5 milliamps in the third.May not be intuitive, but since the scales are labeled in mA, the display is in mA also. This is not unique to cheap DMMs, it is true on virtually every one I have owned. If it were a Fluke or some other name brand people would tell you to RTFM, but the cheap DMMs may or may not have had a meaningful manual. Another way to bring home the thought is to think of the resistance scales. Usually you read the display as ohms, kohms or megohms depending on a switch or dial setting.

author: xani
author_rank: Frequent Contributor
timestamp: March 31, 2017, 11:02:09 pm
content: Maaaaaaaybe you should've bought auto-ranging meter but I guess it is too late for that

author: raspberrypi
author_rank: Frequent Contributor
timestamp: April 01, 2017, 12:35:49 am
content: Quote from: xani on March 31, 2017, 11:02:09 pmI needed cheap and quick. I'm going to invest in two eevblog ones when I have the funds.

author: alsetalokin4017
author_rank: Super Contributor
timestamp: April 01, 2017, 02:55:36 am
content: Yes. In the last photo for example the meter is set to the 20 mA range (20m) and is reading 6.46 mA.On my meters I've used a white or silver marker to mark the "dot" or arrow indicator on the knob to make it easier to see where it's pointed. Or on the red plastic meter knobs I mark the arrow with a black marker. Whatever makes it easier to see.These cheap meters are fine for the kind of work you are doing. They actually are quite accurate, and the construction is "good enough". If you drop it or step on it, it is easy and cheap to just toss it and buy another one. When you start paying 60 bucks for a meter that really isn't much better than these... it gets a lot harder to toss it if it breaks. Of course, once you get serious and buy yourself a Fluke 87-V.... the whole picture changes.(I do wish the cheap ones had better transistor sockets though. Most of the ones I've tried have really loose contacts and it's hard to get a transistor to make good connections in them.)

author: raspberrypi
author_rank: Frequent Contributor
timestamp: April 01, 2017, 04:24:47 am
content: Quote from: blueskull on April 01, 2017, 03:10:10 am1. I'm legally blind2. I'm legally Blind3. Thats called giving into a disability and very discouraging when you are trying to get your life back on track after losing your vision.4. My fluke just broke.To every one ELSE in this thread, thank you I couldn't see the scale and it seems to be upside down of how you would think it would work. It is good to know I have the resources of qualified people to help out with something so simple as not seeing the scale, and saves my hours of frustration.I am going to get I are on high, now.

author: CatalinaWOW
author_rank: Super Contributor
timestamp: April 01, 2017, 04:42:58 am
content: Quote from: raspberrypi on April 01, 2017, 04:24:47 amI am not sure which form of blindness you have, but there are visual aids that can help to resolve many of the issues of the visually impaired. For item 1 everything from using your cell phone in macro mode so you can see a magnified version of the display up through specialized camera/display systems. Or more old school the magnifying goggles worn over glasses. The set I have cost well under $10 at one of the surplus stores (All Electronics if I remember correctly). A set of loupes (a couple of bucks at Harbor Freight) helps a lot. For item 2 there are many, many aids for the visually impaired built into Windows and other operating systems. I have worked with colleagues who are totally, not just legally blind, and they manage to communicate well. I can't speak to the level of difficulty, but they manage. Their ability to perform high level engineering jobs always earned my respect. They clearly use their memory very effectively.

author: SkyMaster
author_rank: Frequent Contributor
timestamp: April 01, 2017, 05:56:52 pm
content: EMPATHY: The ability to understand and share the feelings of another.

author: rstofer
author_rank: Super Contributor
timestamp: April 01, 2017, 08:23:07 pm
content: One issue with meters lacking auto-ranging is probing more or less unknown circuits. I'm not sure it is a good idea to probe 200V while on the 2V scale.In general, we should know what to expect of the meter reading. We know we can't stuff 5A through a 5 Mohm resistor with a 5V source. Just a quick mental calculation shows we are down in the uA range. If the reading doesn't correspond with our quick calculation, the reading is wrong. Or we're measuring the wrong thing!In the day of the VOM, it was unwise to start at a low scale and peg the meter. Meters were expensive and unbending a needle was seldom satisfactory. And, obviously, VOMs didn't auto-range. There was a time before fused meters and measuring 480VAC on the 10A scale was a disaster. Plastic meter case everywhere!

author: DimitriP
author_rank: Super Contributor
timestamp: April 01, 2017, 08:32:58 pm
content: Quote from: SkyMaster on April 01, 2017, 05:56:52 pm1. He is not Canadian.2. He is not Canadian.(Yes it sounds repetitive but I've seen it being done before and it does the job).

author: Seekonk
author_rank: Super Contributor
timestamp: April 01, 2017, 09:23:15 pm
content: I hate auto ranging meters. Just as you get used to looking at certain numbers the scale changes.Think of it, with only 3 1/2 digits how could you display 0.05 milliamps. That is why all meters do this.Asking a question on the internet is something everyone should avoid.

author: tooki
author_rank: Super Contributor
timestamp: April 02, 2017, 12:27:48 am
content: Quote from: raspberrypi on April 01, 2017, 04:24:47 amThere's nothing wrong with those meters for this application, they're more than accurate enough, and perfectly safe at these types of voltages. You've learned to pay closer attention to the range, and all is well in the world (aside from a certain prick here who needs a dose of empathy/compassion).But I am curious, what did you mean that the scale is "upside down of how you would think it would work"? It looks like a standard range switch for a manual ranging meter, i.e. clockwise, the ranges go up (like how the needle on an analog meter turns clockwise as the signal increases).

author: EPTech
author_rank: Regular Contributor
timestamp: April 02, 2017, 01:42:26 am
content: Hi there,I do not know the severity of your blindness but here is an idea: Take a picture of just the dial, scale it to a full sheet size, print it out and hang it in front of you.Or have somebody make spread sheet with the the ranges written in large and the number of clicks and direction you need to turn the switch from the off position to get to that range.I can imagine that magnifying glasses are not always an option as you need both hands for most of the work on the bench.

author: Nusa
author_rank: Super Contributor
timestamp: April 02, 2017, 02:37:00 am
content: If you do get another meter, I suggest finding one with a serial or usb output and matching PC software. Aside from the obvious datalogging capability, it gives you the flexibility of putting your meter output on a PC screen.For instance, my UT61E came with software that repeats the meter display on my PC, as well as logging the data and graphing it for me. If an even larger display is needed, the standard screen Magnifier program should work.I've also seen a few projects where the serial output was used to make a talking multi-meter.

author: Cerebus
author_rank: Super Contributor
timestamp: April 02, 2017, 02:49:51 am
content: Quote from: EPTech on April 02, 2017, 01:42:26 amI think that part of the problem here is that, if I remember correctly, RaspberryPi has lost his sight relatively recently and so hasn't learned some of the coping techniques that come naturally to people who have been sight impaired for a long time. I had a blind friend who seemed to effortlessly remember the physical position of settings on controls. It only seemed effortless because he'd been doing it for a long time. Without looking I haven't a clue where all the settings are on my Fluke except that the DC ones are in the anti-clockwise half, AC clockwise and volts is the first thing away from the vertical either way. Gives one pause for thought, I don't know how well I'd adapt if I found myself severely visually impaired in six months time.

author: EPTech
author_rank: Regular Contributor
timestamp: April 02, 2017, 03:36:44 am
content: Yes, indeed, that is exactly what I am saying.I would surround myself with visual aids like the one I suggested just because of the fact that I obviously do not know where the VAC setting is on my meter is.That being said, I wish for him to keep on doing electronics stuff as he does, utmost respect.Happy measuring.

author: CatalinaWOW
author_rank: Super Contributor
timestamp: April 02, 2017, 05:55:27 am
content: There are often community resources for training blind skills. Unfortunately it is very common, so the need is widely filled. They give tips and training. Things like gluing little felt dots at appropriate places around a dial to provide additional tactile reference. Or always making the black lead shorter than the red lead, and putting a rubber band around it, so that it can be distinguished by touch.I am lucky, other than presbyopia my vision is basically intact. But I have many peers and colleagues who have not been so lucky.

author: ebastler
author_rank: Super Contributor
timestamp: April 02, 2017, 03:26:32 pm
content: Quote from: blueskull on April 01, 2017, 04:57:25 amYou might want to re-read your signature every now and then, and give it some thought?

author: james_s
author_rank: Super Contributor
timestamp: April 02, 2017, 08:11:46 pm
content: Quote from: Seekonk on April 01, 2017, 09:23:15 pmMy meters auto-range by default but you can manually lock in the range if you want. I find that very convenient, it will autorange and then if I'm having problems with the range jumping around I just hit the range button and it holds the range it last selected.

author: IanB
author_rank: Super Contributor
timestamp: April 02, 2017, 08:41:37 pm
content: There is really no reason for the first post in this thread. Firstly the poster was apparently able to read the numbers on the display quite accurately. Secondly there are photos of the setup that can be zoomed in or enlarged to any amount, and which clearly show the selector turned to the 20 mA range and the test lead plugged into the mA socket. Thirdly, even without good sight there is the tactile feel of turning the selection knob. It is easy to learn that the 20 mA range is 5 clicks to the right from the off position.

author: Cerebus
author_rank: Super Contributor
timestamp: April 02, 2017, 08:47:41 pm
content: Quote from: blueskull on April 02, 2017, 06:01:17 pmThe O.P. has had the signature on the post you were commenting to for quite some time because some people couldn't account for the possibility that other people, as it turned out literally, see things differently which caused him to be accused of trolling or similar by others, and now by you. Perhaps you should have bothered to read that signature and then you wouldn't have failed to be cognisant of his handicap and made such a fool of yourself.

author: guenthert
author_rank: Frequent Contributor
timestamp: April 02, 2017, 09:51:01 pm
content: I promised myself to stay out of this kind of discussions, but I can't help myself right now. I don't quite understand why blueskull is now on the receiving end of the collective eevblog wrath. I read his post as earnest, if harsh, attempts at help. I'm in the lucky position to be only slightly vision impaired (but getting into an age where this becomes worse). I find reading labels on chips quite difficult at times, as they are really of amazing low contrast. So I wonder, if electronics is really the best venue, if one is legally blind. Is then looking for something else to do giving in to disability, as the OP states or is it giving in to reason (and given the topic he's not giving up too much)?I actually came here because of the thread's title -- I can't stand those categorical rejection of Chinese products. A good share of all products come from China now and it's certainly not all poor quality (as it might have been in the seventies and eighties). Afaik, the iPhone comes from there too. The old-timers might fondly remember the 'Made in W. Germany', but surely there were duds with that label too (I think the VW Golf I, sold as 'rabbit' in the US, was one).

author: Cerebus
author_rank: Super Contributor
timestamp: April 02, 2017, 10:22:37 pm
content: Quote from: blueskull on April 02, 2017, 09:32:14 pmSo let me see, your justification for this is "Two wrongs make a right". You were, at best, insensitive towards a handicapped person when the evidence for their handicap was staring you in the face, at worst deliberately offensive - only you know which it was. It doesn't matter who it is, or what they have done, you don't pick on people over things they have no control over, be that colour of skin, handicap, gender or whatever. That's not PC platitudes, it's common decency. That's what's got people's panties in a bunch about your behaviour.

author: timb
author_rank: Super Contributor
timestamp: April 02, 2017, 11:10:34 pm
content: Quote from: Cerebus on April 02, 2017, 10:22:37 pmJust FYI, not everyone can see user signatures. For example, Tapatalk does not show the normal user signature at the bottom of their posts, nor does it show the custom user tag that's under their username like the normal forum web view does. In Tapatalk, I see their profile picture, username and post, that's it. (Which is actually quite nice as it's a lot less cluttered!)Also, since you're trying to be PC, you should know handicapped is no longer the apropos term. Try "handicapable" instead. "Differentlyabled" is also acceptable. ;>Anyway, I had no idea the OP was visually impaired until he said something, although it explains a lot now that I know. He's also fairly young if I recall correctly, so everyone should keep that in mind and cut him a bit of slack. I think he's honestly trying and maybe just has a weird sense of humor on top of everything else (or doesn't understand about sarcasm and the internet), that's why his posts come off the way they do.

author: Cerebus
author_rank: Super Contributor
timestamp: April 02, 2017, 11:16:18 pm
content: Quote from: blueskull on April 02, 2017, 10:30:44 pmYou're not worth the candle mate, you've made that quite clear. If you want to make any more threatening noises from behind your keyboard feel free, but I won't be listening to them and I won't be responding. I've no desire to have the pointless slanging march that you seem to be asking for. At some point in real life you are going to get yourself into a situation where your attitude and behaviour is going to do you real harm, where the consequences aren't mild, polite rebuke from behind another keyboard but a lost job, or a good hard kicking from some red-neck whose tolerance for your 'I can say what I like about who I like' attitude isn't as mild as mine. Good luck, I suspect you're going to need it.

author: DimitriP
author_rank: Super Contributor
timestamp: April 02, 2017, 11:21:41 pm
content: QuoteYou can say that again!!!Unfortunately there is always someone willing to post a To-Long-T-Read diatrabe on the subject. Which only propagates the problem.QuoteI believe there was a really really crappy version that ended up getting sent here. In the 80's the european "versiions" were not as crappy and looked a lot better than the tuna cans they sent here.QuoteCollective maybe, but certainly not unanimous !!!QuoteThe dynamic range of your opinion is highly compressed.How about he responded as if it was anyone else complaining about their dog eating their homework and they need help "right now"!!!.QuotePosting history shows plenty of common decency.QuoteYou can speak for yourself all day long.Not everyone panties got in a bunch. Good for him to speak up and say what other were also thinking!!!Quote

author: Cerebus
author_rank: Super Contributor
timestamp: April 02, 2017, 11:24:17 pm
content: Quote from: timb on April 02, 2017, 11:10:34 pmI didn't realise that. Which would take the wind from my sails, save that Blueskull has now made it abundantly clear that this is personal animus and that the facts of the case are now probably completely irrelevant.Quote from: timb on April 02, 2017, 11:10:34 pmThe very last thing I'm trying to be is PC. Hell, I'm a London Eastender, we don't know how to be PC. My mother used to describe my Father as a man who wouldn't "call a spade a spade, he'd call it a bloody shovel" - I take after him. I just don't believe in seeing a man kicked when he's down.

author: Mr. Scram
author_rank: Super Contributor
timestamp: April 02, 2017, 11:58:53 pm
content: Quote from: Seekonk on April 01, 2017, 09:23:15 pmI always wondered why people were so adamant about auto-ranging meters, but your post confirms my feelings. I do think they can be useful and easy, but they also sometimes jump all over the place without a chance of seeing what you are dealing with. Having both types around certainly does not seem to hurt.Quote from: blueskull on April 02, 2017, 11:36:28 pmI like that one, I need to remember it.

author: RobertHolcombe
author_rank: Frequent Contributor
timestamp: April 03, 2017, 02:46:26 am
content: Quote from: Mr. Scram on April 02, 2017, 11:58:53 pmA decent auto-ranging meter will have a range button allowing selection of manual ranges. Working as a tech I can only think of a handful of times I've needed to disable the auto range function, but you're right; it is invaluable when a voltage is alternating between ranges.

author: neko efecktz
author_rank: Regular Contributor
timestamp: April 03, 2017, 03:53:03 am
content: WHY DON'Y YOU ALL JUST DROP IT.Raspberrypi has a vision problem and misread his meter that I believe he has only just recently purchased due to the failure of his fluke.You are all wrong and you are all right.Now he probably feels like a fool for not seeing the obvious.I would hate to see someone being driven away from a valuable forum as this.I myself sometimes have trouble seeing settings on my meters and other test equipment.I need to ware reading glasses, intermediate and long distance glasses.I need to keep changing them while i work. and at home.please be a little more compassionate towards others.BILL

author: Mr. Scram
author_rank: Super Contributor
timestamp: April 03, 2017, 05:20:52 am
content: Quote from: neko efecktz on April 03, 2017, 03:53:03 amDropping it might harm the calibration, so I'd rather keep my DMM on the table.

author: tooki
author_rank: Super Contributor
timestamp: April 03, 2017, 09:36:16 am
content: Quote from: neko efecktz on April 03, 2017, 03:53:03 amFor sure, this forum can occasionally demonstrate some of the stereotypical engineer traits of not being terribly good with novices, overwhelming us beginners with correct information that is nonetheless useless because it far exceeds our current skill level, knowledge, or understanding. (But in all fairness, this forum is a lot better for beginners than anything I've seen in Linux or Arduino forums, and for this I am thankful.)As for disability, I assume others will join me in making the following offer:raspberrypi (or anyone else who needs it), if you are having trouble reading something, send the PDF, screenshot, or photo and I will do my best to help you out.

author: Gyro
author_rank: Super Contributor
timestamp: April 03, 2017, 01:33:25 pm
content: I know a number of us here are industry professionals [Edit: and of course others] who have had to give up due to health issues of one kind of another. We generally hang out here for a bit of light relief / keeping our hand in / an opportunity to pass on some knowledge / get out from under the wife's (sorry, 'significant other's') feet, etc. Maybe we should all change our sigs to provide some explanation for our sometimes inexplicable behavior...I'm thinking about changing mine to:---------------------------------------------------------------------------------------------------------------------------ChrisBrain tumour... may make me slow on the uptake, easy to confuse, prone to error, and generally behave like Victor Meldrew!

author: Mr. Scram
author_rank: Super Contributor
timestamp: April 03, 2017, 07:50:45 pm
content: Quote from: Gyro on April 03, 2017, 01:33:25 pmThe story you guys are telling are hitting me hard. It is so easy to forget the luxury of the position you're in.

author: Gyro
author_rank: Super Contributor
timestamp: April 03, 2017, 08:08:51 pm
content: Hey, I get some more time to play with my toys instead of fighting issues in the office. It's not all bad!Edit: Of course I'm lucky that it has come near the end ofmycareer, it's not necessarily the same in other cases.

author: Kilrah
author_rank: Unknown
timestamp: April 03, 2017, 08:26:12 pm
content: OP asked "Who is on crack? Me or the chinese DMM?" as a topic title, followed by "Or am I just blind" which anybody would say to suggest "am I just being a dumbass?" - Nothing in this suggest he'sactuallyblind/suffering from bad eyesight. Rather sounds humoristic/provocative, and will thus attract a similar tone in the answers.So it's kinda obvious the answers would be either "you're on crack" or "you're blind" or "WTF what a bad joke" when the first thing you see is that the meter is set on the mA range. Especially when posted on April fools day...Any misinterpretation/confusion/excessively harsh answer on here is entirely down to OP's own wording. Had he asked "I've got bad eyesight and must be missing something, could someone help me find out where I'm wrong?" people would have understood and been nice.

author: Mr. Scram
author_rank: Super Contributor
timestamp: April 03, 2017, 08:39:51 pm
content: Quote from: Gyro on April 03, 2017, 08:08:51 pmI am glad to hear you are doing okay. You are probably right about the second part too. If I am honest about what I look for in life, it is probably relevance beyond anything else, professionally and elsewhere. Money and material things are nice and would not mind having more, but at the same time I know they do not fulfil my needs at all, other than them allowing me to do those relevant things. The chance of something impeding that relevance even making it impossible scares me more than I would generally admit. It scares me a lot.I guess that concludes this episode of my diary.

author: Zero999
author_rank: Super Contributor
timestamp: April 03, 2017, 09:09:02 pm
content: Quote from: timb on April 02, 2017, 11:10:34 pmLol, neither "handicapable" instead or "Differentlyabled" are in my dictionary. Perhaps it needs an update?Bah, PC is bullshit. What's offensive changes over time and from place to place. A hundred years ago it was fine to use words, such as idiot and moron refer to someone with a low IQ, but that was offensive, so professionals started to refer to them as mentally retarded and now that's offensive so terms such as intellectual disability are used.I'm all for showing understanding and treating others with respect but PC has gone too far.

author: Bud
author_rank: Super Contributor
timestamp: April 04, 2017, 04:01:21 am
content: Quote from: timb on April 02, 2017, 11:10:34 pmNo you do not recall correctly. By his own words he came to his dad's shack in 80-s as a kid.Or if he did not , that just proves he is a troll.I said a couple times before he is a troll. I bet he is sitting now in his chair and laughing his ass out reading this thread. This is what trolls do. Spark heated conversations then step back and enjoy the show.Those talking about his blindness - I beg you to tell where did you see his medical record.Or this is what HE told you?

author: Nusa
author_rank: Super Contributor
timestamp: April 04, 2017, 04:55:52 am
content: Young is relative. Those that were kids in the 80's are younger than me, and I'm still a bit shy of claiming senior citizen discounts.

author: RGB255_0_0
author_rank: Frequent Contributor
timestamp: April 04, 2017, 07:47:05 am
content: This thread has been entertaining since raspberry got banned. He's really trolled the living shit way passed his RIP date and thus succeeded in what he came here to do: causing an intra-forum fight. 10/10 troll.

author: rrinker
author_rank: Super Contributor
timestamp: April 04, 2017, 05:37:52 pm
content: Possible problem with an autoranging meter - it will display the same 5.05 on the display but then a little ma annunciator to let you know it is 5.05 ma and not 5.05 amps. If reading the LCD is not a problem for you, then autoranging might avoid this. But if you have trouble reading the smaller markings on the LCD ( I don't know of any of the popular meters where the units part is as large as the digits - but I'll bet there's something out there), then just learning the dial positions of the manual range meter may be more usable as you can tell where the knob is turned by touch alone. I'm not sure exactly where your vision level falls, I can still read displays on meters and screens with no problem (with corrective lenses, without I cannot see clearly past my nose) and glaucoma has taken about 50% of the visual field of my right eye, so I pretty much have to view everything from my left eye with a little bit of fill in from the right but it's distracting since it shows up as a haze in the areas where the optic nerve is damaged on the right. I've had surgery in both eyes to keep the right from getting worse and to prevent damage to the left. There's a good reason I haven't attempted SMD soldering by hand. Even with my USB microscope at a 27" display, which makes an SMD resistor look HUGE - it's not about the size or focus, it's about the clarity.

author: Zero999
author_rank: Super Contributor
timestamp: April 04, 2017, 05:47:44 pm
content: Quote from: RGB255_0_0 on April 04, 2017, 07:47:05 amIs he banned? That's the first I've ever heard of it.I'm not sure if he's a troll but most of the threads he's created have turned to petty flaming, so I can see why.

author: CatalinaWOW
author_rank: Super Contributor
timestamp: April 04, 2017, 05:50:58 pm
content: It would explain why he hasn't been back to re-stir this pot.

author: MK14
author_rank: Super Contributor
timestamp: April 04, 2017, 06:39:57 pm
content: Quote from: Hero999 on April 04, 2017, 05:47:44 pmI've thought/known they were a troll for a very long time. To me it was obvious.He seemed to get banned in another thread, and/or his banning was discussed there.I've not linked to it, because of the nature of it. It was partly deleted (I think) and is best not repeated.Don't worry, you are not missing anything interesting, it was nonsense (apparently), but readily ban worthy.

author: KL27x
author_rank: Super Contributor
timestamp: April 05, 2017, 07:38:45 am
content: Totally unrelated to raspberry. I know a girl who started a fundraiser when she found out she was legally blind. Yeah, I say "found out." I wonder if her doctor told her she was legally blind in one eye, or something. Which is something of an oxymoron and isn't actually legally blind, lol. Or maybe she heard she is "legally blind" without corrective lenses, which is also not technically being legally blind. I'm fairly certain she is not legally blind, because... she drives. A car.Raspberry. No offense meant to you, if you're reading this with super big font for legally blind people and/or "the squint."