oh no, DMM says "0L" for everything... lol - Page 1
Forum section: electronics / beginners

author: multimeta
author_rank: Newbie
timestamp: September 01, 2017, 01:52:41 pm
content: Hi, first post!THERE'S TWO SECTIONS TO MY POST - I'd really appreciate if your reply was **equally responsive to both sections;** I feel SECTION2 outweighs the other due to the thought of SAFETY.SECTION 1: PROBLEMSI bought a cheap $25 (digitech qm-1527) meter and read the manual earlier today. The resistance range displays 0L no matter what, and in the cont.-beep mode I just get 0L even if I touch probes (smirk) for a long time.Putting in a new battery makes the unit behave weird. Maybe my battery is too powerful. The meter reads new battery at 9.4 volts, and with it installed the unit reads the factory-supplied battery at 8.4v.Whilst the new battery (9.4v) was installed the following occured;- enabling display backlight leads to greatly inaccurate voltage reading. AAA (marked 1.2v) batteries previously reading 1.34v now read around 2v, and my 1.55V AA batteries now read over 2v (making me even change voltage range for the inaccuracy).- device does not turn off sometimes, and the battery symbol is now activated. Power cycling is now a strange excersize.SECTION 2: CONCERNSMy fault?> With the meter I measured a laptop cell stripped from a laptop's battery (at this moment I was in 10A fused, with 10A on the scale also) reading over the 10A rating - I saw a number 11 and quickly removed the probes to prevent damage etc. This was the first thing I did with the unit.Saftey concern> Since realising these oddities I've been measuring AA and AAA batteries as means for sanity checking. During this process I've experienced odd sensations in my body, specifically my thumbs become warmer than palms after reading (my thumbs hold the probes; correlation?), and there is a mild impairment of logic/cognition (placebo?), as well as mild (mild-mild) turning of the stomach. My symptoms are so weak I feel as though they can't truly be the cause of anything but my mind, however, at the time noticing these symptoms is alarming, as I notice the warmth of my thumbs for no apparent reason, and how they are never warm in this manner! And how my stomach does not ebb or flow in this way, and lastly how usually I am not feeling strangeness across my body in manners I don't understand. This is possibly placebo, but could it possibly be the meter?^^In regards to this "safety concern", I might add these symptoms occur simply from measuring AA, AAA and 9V battery cells. I'd assume these to be harmless devices. The unit itself is powered by a 9V device.

author: kalel
author_rank: Frequent Contributor
timestamp: September 01, 2017, 02:26:38 pm
content: Hi there, welcome!As a small tip, it might be easier to read your post with the normal font.As for the meter, there are experts here that might be able to help.As for the symptoms, as you yourself describe them as strange sensations, it could be placebo as you say, that is, perhaps you expect something to go wrong (maybe you don't feel the meter is very good). Maybe once you have a little bit more confidence, it will feel better? As a newbie myself, when working on projects sometimes I feel "this wire/resistor/transistor/etc must be getting hot", because I almost expect to have shorted something or for something to go wrong.But usually when I touch it again, I notice it's not hot at all, unless if I did really short something.As for the safety of batteries, I'm by no means an expert, but I do believe the batteries are not unsafe when used properly. Perhaps when shorting them out (e.g. with a piece of wire), you can get very high temperatures, and burn your finger if you're holding the wire. Make sure to check the voltage, and not current of batteries (or any other power source) directly with a multimeter.

author: Zero999
author_rank: Super Contributor
timestamp: September 01, 2017, 02:32:23 pm
content: Quote from: multimeta on September 01, 2017, 01:52:41 pmSounds like cheap rubbish and you might have damaged it.QuoteWhat did you do? Set the meter to current mode and put it across the battery? No, don't to that. It will short circuit the battery and could damage both the battery and meter. Batteries are constant voltage devices with a capacity normally specified in Ah or mAh, which is how much current they can produce for an hour. The short circuit current could be as much as a hundred times the Ah value.QuoteThose symptoms don't even match an electric shock. Placebo. It sounds like anxiety to me and could be caused by you feeling uncomfortable with what you're doing.

author: multimeta
author_rank: Newbie
timestamp: September 01, 2017, 02:39:14 pm
content: Thanks that helped a lot :praise:I know this stuff yet couldn't bring the right frame of mind in.Hopefully even more study helps prevent this silliness in future.