The There Are No Stupid Questions Thread

[Scallywag]

@Sidney Stratton

@ CRC:

That overly lengthy post is TL;DR. Trim your responses down. If you have to, make multiple responses directed at each post and use …/ for shorthand (especially for Correllux’s response(s) – he tends to get carried away).

Remember that these aren’t rules anywhere, and just suggestions based on opinion.

Feel free to post as long or short as you want and as concise as you want to be, or not. Sidney might not read your longer posts but some of us have short attention spans.

Oh look! A butterfly

[Sidney_Stratton]

Huh? You endorse this repetitive posting?

[Rayoui]

I know there’s a few people that are really outspoken about it but it doesn’t really bother me either

[CollectEverything]

Long posts should be no problem…evaluate whether it is information you need and then either read it or don’t.

[Sidney_Stratton]

CRC quoted post #1594 in its entirety – only to comment “Wow, thank you for all the valuable information and lvideo links.
Sorry for the late reply, and im only just seeing this now so I still have to check it all out…/”
(there are more of his responses but they get buried).

Then added Post #1601 xevious: “Another good channel is Afrotechmods…/”

Surely this could have been condensed in a smaller package without losing its response.

It is not the lengthy responses of the members that are at play, but the attachment of such to voice an opinion.

Take for example that last one. Could have been shortened to:
@ xevious: regarding Afrotechmods – Thanks for the video and channel suggestion…/

Now, I’m not condoning Correllux nor xevious’ posts, but the re-iteration and the mishmash that ensures.

Just a pragmatic observation.

[Scallywag]

@CRC

@JasonWW

@CRC

So I finally got the miltimeter ive been waiting for.
Not quite what I was expecting…
Seems like a peice of junk to me.
How do I check a batteries voltage with this thing?
What do I set the dial to?
I know nothing.

The V~ is your AC (alternating current) like in your house.
The V-… is your DC (direct current) like in a battery.
The different numbers are just the max ranges. You could measure the battery voltage at 1000 volts, but you won’t have enough accuracy.
The 2000m is 2000 millivolts (or 2 volts). Thats not enough for your battery so 20 volts is the best option.

Okay, awesome. so I know how to check my cells voltage now. Thank you.

@JasonWW

The horseshoe is Omega or ohms. That measures resistance.

The A is DC amperage. You have to be careful using this. Or at least the 10 amp setting which requires you to move the red probe to that other port. Try not to use that at all and leave your probes in their current positions.

I have no intentions of using this meter to do anything other than see what a cells votage is sitting at. So it will only ever be set to the one setting and the probes will only ever go in the one way.

@JasonWW

I would have recommended a different DMM. One that auto ranges and auto turns off. This one looks like to have to remember to turn it off manually. If not, you’ll run the battery down and that sucks.

This one was given to me for free after waiting a while for it. Its my first one, so ill just get used to knowing to turn it off when im done.

@Correllux

@CRC

I got this multimeter for free.
Just been waiting months for my dad to dig it out of storage for me.
Im a complete electrical newb.
Over the years, ive tried to understand electricity multiple times for one reaon or another and I never make any progress.
its just waaaay beyond me.

Im just trying to make sure my flashlight cells are where theyre supposed to be.
Thats all I plan on using the multimeter for.

Never worked with series and parallel circuits I presume.

Correct.

You’ll need some beginner’s guide on how to make measurements of voltage and current

What more do I need to know beyond setting the dial to the correct spot, touch the probes to the battery, and read the screen?

Searched around a little for some good tutorials…man there’s a lot of junk info out there. Here are a couple good videos and articles that should help you. Nuts and bolts stuff for using meters and basic tests, but it would pay to check out some of the basic conceptual stuff about electricity in general. You’ve already got some letters in the alphabet soup, so it’ll get easier as you gain some more and understanding falls into place. It’s a lot easier to learn hands-on with someone showing you, but videos can take the place of that sometimes and there are tons of “makers” around these days with content (and sites like Adafruit and such have a little bit…these links seemed better to me, though).

This is good and kinda gets straight to the point for you with batteries, then really basic LED circuits (like stuff you might do modding an ultra cheap flashlight that doesn’t have much in the way of a driver to control things). Could be the best seventeen minutes of your life: https://www.youtube.com/watch?v=ts0EVc9vXcs

https://www.youtube.com/watch?v=ts0EVc9vXcs

This channel - “The Engineering Mindset” - is really excellent. He’s done a marvelous job illustrating concepts for general stuff, components, and circuits (and other things) and presents them in a way that is easy to grasp. I found that channel while searching for things about neutral lines (A/C) and some hvac stuff, then saw how many great videos he has. He doesn’t have a good one for basic multimeters but there is this one on battery testing. He shows the correct way to test cells with a small load applied (resistor) so that you can see if a cell is behaving nicely rather than just looking at voltage alone. This isn’t really necessary for our li-ion flashlight batteries but it can be important for lithium primaries (coin cells, etc), silver oxide, alkalines. He does have lots of individual videos covering the basics like voltage and current and resistance and inductance, etc., and when you feel like it those would probably be very helpful for you. But using your meter for the basic nuts and bolts you don’t necessarily need to know all of that. If you search his vids for “multimeter” most of those will come up close to the top of the list.

HOWEVER….safety is important, and other than remembering not to short things out accidentally, I have to mention that our DC low-voltage flashlight circuits and most things on circuit boards and components are generally pretty safe. When you move over to equipment like motors and air conditioners and automotive, you really need to know more about what you’re doing and how those things are assembled, and proper testing procedures for them. There are chances for a nasty shock (larger batteries or current, larger capacitors, etc), and also bigger potential to damage parts (mechanical and electrical both…or your meter).

That video: https://www.youtube.com/watch?v=JjElWj0fFX4

https://www.youtube.com/watch?v=JjElWj0fFX4

And a couple good articles with some of the same info plus a little more explanation of the settings/symbols on the meter:

How to use a Multimeter? A Complete Beginner’s Guide

Multimeter Symbols - ElectronicsHub

All that said, other things you should know about your meter. First is that they need a fresh, strong battery inside. The battery is the power source for most tests…it feeds energy into a little circuit which the meter uses to determine voltage measurements and if the battery gets low and can’t provide enough juice, your readings may get very inaccurate or shift around as you watch the screen. This can happen before any “low battery” symbol appears on the screen. So always remember to turn it off and keep the battery fresh.

The test leads with that meter are on the fragile side of life, so be gentle with them…that’s true for both ends of the leads. Usually the nickled pointed probes that go back into the handles do not have a good design for connecting the wire, and the wires are roughly solder right onto them…and those wires are usually pretty tiny and poorer quality, too, so they’re easy to break just by bending or may break or come loose with a little tugging. If you want to wrap the leads around the unit for storage, don’t do it tightly. You can get replacement leads (actually those same leads are often like $0.40 on aliexpress…maybe $5 if you were to find them in a retail store), but for a freebie and for a cheap meter, it would make more sense just to buy a new slightly nicer meter instead. Of course you can try to fix broken leads, too.

Back to safety. Although this meter will do some A/C basics, it’s really not a great or safe meter for that, in my and most others’ opinions on these. So if you want to check outlets and cords or lamp sockets and such, just be sure you understand what you’re doing so you don’t pop a breaker or scorch something, blow the meter fuse/meter itself, etc. These are best for simple checks on low volt electronics and such, and they do ok there.

Safety and probes……for flashlights and whatnot, it doesn’t matter if your skin is touching the probe tips or wires, components, etc. But do get in the habit of avoiding that whenever possible, and keeping fingertips behind the little protective circle disk things on the probes so skin doesn’t contact them or circuits…it’s just wise. With high powered circuits and with A/C there can be a potential of arcing in some situations, so keeping skin back and touching only insulation is a good habit (and in those cases, better leads are really required). Also a good habit to try and honor polarity (red/positive to positive and black/common/negative to negative)…for many functions the meter will handle it either way without worry but sometimes it does matter and sometimes it’s unsafe to reverse them (for things like diodes/leds it’s kind of mandatory to test operating function but you also check those in both directions/polarity anyway).

When using the leads, remember that firm contact makes a good connection, so press them lightly into the metal of terminals/legs/solder joints, or in the case of bare wire (with flashlights) you can squeeze the wire to the probes with fingers. If you just let the probes barely touch the contacts, sometimes you’ll get inaccurate or wandering readings, and some batteries have coatings on them that you need to get through (or oxidation, even if they look clean). You don’t have to press hard, just firm, and remember that these leads are kinda fragile. Also, wipe off the leads before you use them…a little alcohol once in awhile…just like flashlight threads, any grease or grime there may interfere with good contact.

Anyway, glad you got a meter! Should put your mind at ease and it can be fun to look deeper into your stuff. It’s interesting to see how cells bounce back up a little in voltage after the load is removed from them…some bounce back faster or more than others. You can check out tailcamp current (amps) for many of your flashlights, too…even if that’s not the most accurate/truth (vs current at the emitter itself) you can get a good idea of the power and can also compare different batteries’ delivery.

Wow, thank you for all the valuable information and lvideo links.
Sorry for the late reply, and im only just seeing this now so I still have to check it all out.

Im only really planning on using the multimeter to check the voltage of a cell.
Beyond that, I have no plans to use it for anything else.
If something were to come up that I thought I might want to try and use it, I would then do the same kind of “research” im dong here before attempting anything.
Im not messing around with anything dangerous ignorantly.

@xevious

@Correllux

Searched around a little for some good tutorials…man there’s a lot of junk info out there. Here are a couple good videos and articles that should help you. Nuts and bolts stuff for using meters and basic tests, but it would pay to check out some of the basic conceptual stuff about electricity in general. You’ve already got some letters in the alphabet soup, so it’ll get easier as you gain some more and understanding falls into place. It’s a lot easier to learn hands-on with someone showing you, but videos can take the place of that sometimes and there are tons of “makers” around these days with content (and sites like Adafruit and such have a little bit…these links seemed better to me, though).

This is good and kinda gets straight to the point for you with batteries, then really basic LED circuits (like stuff you might do modding an ultra cheap flashlight that doesn’t have much in the way of a driver to control things). Could be the best seventeen minutes of your life: https://www.youtube.com/watch?v=ts0EVc9vXcs

https://www.youtube.com/watch?v=ts0EVc9vXcs

Another good channel is Afrotechmods. Just saw this one on batteries and learned a good bit from it:

https://www.youtube.com/watch?v=cxkVxi9P0EA

I agree, it’s a great idea to have a multimeter handy. You don’t need to be an expert to use one and there’s so many online sources to help you figure out functions, as you listed. I think it’s a good idea to get a quality one versus a cheap one. FLUKE is a brand I trust. There have been some electrician courses where they mandate a certain multimeter, and then afterwards some people drop out of the program and put their multimeter up on eBay. I bought a Fluke 73-III model back in 2009 for $60 shipped, in gently used condition with the rugged yellow outer protective shell (removable). I’m seeing you can still find them for about that much on eBay these days.

Thanks for the video and channel suggestion, I’ll check it out.
As I said above, Im only using it to check a cells voltage. The one I have should be good for a while I think.
I’ll eventually probably get the one that I keep seeing go on sale at CanadianTire from $30 down to $15.

Yeah, I don’t see an issue with this at all. Additionally, if one quotes a post, they are preserving a copy (in their own post history) whereas in theory the original posted could change or delete their post.

[Rayoui]

@Scallywag

Yeah, I don’t see an issue with this at all. Additionally, if one quotes a post, they are preserving a copy (in their own post history) whereas in theory the original posted could change or delete their post.

Especially if the quoted conversation is relevant to the post, since this forum software doesn’t provide links to the original quoted posts, it prevents having to scroll back (sometimes several pages) to read portions of the original conversation for context.

[story]

Today I reflowed a 219B to the Sofirn SC11 (4x AA). I also put in a spare FC12 LED and board into another SF11. It barely fits into the reflector and I was able to reuse the screws to hold it down. (Beginning’s luck) The beam looks about the same as the Wurkkos FC12. It works and has no problem so far on both SC11. I did a runtime on the 219B and when I realize the SC11 a 6V flashlight, isn’t it? I was using fresh 1.3v Eneloop and it ran for 60 mins to empty, the body heated up about the same as the S2+ with 219B. Does that mean it the 219B will work at ~5.2v for a while until the Eneloop drain to 4.8v steady for a while? Maybe I am in the clear?

Will I run into a problem with the SFT40? It works so far and it’s been running for 30 mins.

[Rayoui]

219b and SFT40 are 3V LEDs. The driver is a buck driver which reduces the voltage of the four cells (which are in series) to the forward voltage of the emitter. It should work fine as long as the combined voltage of the cells is > ~3V. So even if all four cells are almost dead (~0.9V) it should still be able to drive the LED just fine (as long as low voltage protection doesn’t kick in before that).

Hope I understood your question correctly.

[dee-u]

Can LEP technology be used by a nation as a weapon?

[Rayoui]

I guess it could be use as a dazzler. Like a distraction or temporary blinding device. Other than that, I don’t think so. It wouldn’t really provide a huge tactical advantage to a nation state, unlike other devices like microbolometers (thermal cameras) which are regulated as weapons in some countries.

[dee-u]

I am imagining a large one, perhaps installed in an artificial moon or a satellite that could be directed to an enemy state.

[manithree]

@dee-u

I am imagining a large one, perhaps installed in an artificial moon or a satellite that could be directed to an enemy state.

But why, though?

Sure, a laser could be used as a weapon. Not sure how much power you would need to do that from space, but why put a phosphor in front of it for weapons use? Doesn’t make any sense.

[Lightbringer]

@manithree

Sure, a laser could be used as a weapon. Not sure how much power you would need to do that from space, but why put a phosphor in front of it for weapons use? Doesn’t make any sense.

Drive people to kill each other with ugly green-tinted light?

[story]

@Rayoui

219b and SFT40 are 3V LEDs. The driver is a buck driver which reduces the voltage of the four cells (which are in series) to the forward voltage of the emitter. It should work fine as long as the combined voltage of the cells is > ~3V. So even if all four cells are almost dead (~0.9V) it should still be able to drive the LED just fine (as long as low voltage protection doesn’t kick in before that).

Hope I understood your question correctly.

Thanks for the explanation

[CollectEverything]

I know Chinese New Year is generally a bad time to buy something directly from China. Does intl.outdoor.com do things differently being a smaller company, or does the same rule apply? (don’t expect anything you order now to ship till Feb.)

[Mike_C]

Oh? Doesn’t Chinese new year holidays start 31st of January? If so, they still might be able to send it out in time? A few days ago I placed several orders from several large Chinese vendors, in all cases orders where registered as shipped within two days.

[CollectEverything]

@Mike C

Oh? Doesn’t Chinese new year holidays start 31st of January? If so, they still might be able to send it out in time? A few days ago I placed several orders from several large Chinese vendors, in all cases orders where registered as shipped within two days.

Oh weird. I guess that Petrified Fish Store on Aliexpress gave me the wrong idea with their holiday notice.

[Mike_C]

@CollectEverything

Oh weird. I guess that “Petrified Fish Store on Aliexpress gave me the wrong idea with their holiday notice.

I would assume they know their holidays better than I do! I only did a google search on Chinese new years holiday. The result on wikipedia of 16 days off is a lot different to that holiday notice 25 days on your AliExpress store.I guess it’s different from store to store, my AliExpress order was placed on 16th and got an email on the 17th that it was shipped.

[Naito]

If I apply just a little force to the FWAA MCPCB, it lights up at max. What could be the cause?