Basic Flashlight Tutorial | Hacker News Reader

Basic Flashlight Tutorial

asos1.com

102 pointsTomte48 comments

> Most people think it's normal to have to beat on a flashlight to make it work. We do it without thinking. It's almost as if it's coded into our DNA.

Can someone (perhaps older than me (I'm 38)) explain this sentence? I have no idea what it even means to "beat on" a flashlight. You push a button, it turns on. What is there to "beat on"?

edit: Weird. I guess I've never used a cheap flashlight, because I've never had this experience.

At least in almost every horror movie there is a scene when somebody goes down to the basement. Their flashlight starts flickering, then turns off, then they hit it with their hand a few times and it works again. Finally it inevitably fails again and the person gets eaten.

> then they hit it with their hand a few times and it works again.

Just in time to see the antagonist right in front of them.

BOO

Probably most effectively done in the movie Se7en.

> Can someone (perhaps older than me (I'm 38)) explain this sentence? I have no idea what it even means to "beat on" a flashlight. You push a button, it turns on. What is there to "beat on"?

I think it has to do with cheaper flashlights that basically consisted of not much more than a plastic tube, a bulb, and some springs for the electrical contacts. Because the tolerances were so poor, the battery terminals would often lose contact with the metal springs. One solution would be to open the flashlight up and re-set the battery. But usually, giving the case of the flashlight a few whacks was enough to bounce the battery back into a place where the circuit would be completed and the flashlight would turn back on.

I'm 39 and I know exactly what he's talking about. Pick up your average dollar store or Walmart incandescent flashlight, flip on the switch, and no light comes out. This is on a brand new, just out of the package flashlight. Tap or beat on the side of it, and suddenly the light comes on...for a little while. Then it flickers and goes back off, causing another round of tapping and beating.

This is due to the bottom-of-the-barrel cheap components and construction of low cost flashlights. Often the components aren't lined up correctly, or the switch isn't making perfect contact, or the spring is too compressed to push the batteries up against the positive contact (which is often the base of the bulb). I can't count the times I've had to disassemble and repair a cheap plastic flashlight right after opening the package, just to get it to turn on and off reliably.

The old ones that had two to four D cell batteries in serial in them would often get so the connections between the batteries and the terminals in the flashflight casing would be corroded or misaligned. So you turn it on, the light doesn't come on, then you whack it a few times, and things line up and the circuit gets completed to turn on the bulb.

Often times corrosion on battery terminals, or loose connections to the bulb, can cause a flashlight to not turn on when you hit the button. In this case, hitting it into the palm of your hand a few times usually solves the problem, and the photons are free to flee the front end of the flashlight.

You do the a desperate hand dance where you tap the flashlight with you palms, shake it like maracas, and finally stare into the LEDs for answers that aren't there.

And frequently, it's not the shaking or the tapping or the clicking or the tightening of the lens cap or any of the other actions which remove the corrosion, oxidation, or misalignment and reestablish an electrical between the batteries, spring, switch poles, and bulb.

It's the gentle, inquisitive wiggle as you stare directly at the bulb which causes it to turn back on.

For related reasons, never look down the barrel of a gun which has not been sufficiently disassembled. There are no answers there.

AKA Percussive maintenance.

Sometimes, things in older flashlights aren't all aligned or for some reason the circuit just can't complete, so you smack it on your hand and it ... just works. Unless the batteries or bulb truly are dead. Then you just have a sore hand that you can't see.

Oxidation/corrosion at the contact points: Battery to battery, battery to body's contacts, switch...

Marginal batteries: Sharp acceleration shifts internal contents just enough to provide for a more energetic discharge.

In short, yes, it's a real thing. Especially when Dad insists on keeping his 50 year old flashlight and on eking every last electron out of each set of batteries. ;-)

I love this! It's also awesome that the author considers it "basic", at that size and depth of detail.

I mean, it describes the voltage-boosting circuitry of the Proton almost to the point of reverse engineering it. That's great (in my book), but not very basic. :)

This is good, I agree, but I have one major criticism: no mention of safety concerns for running non-rechargeable lithium batteries like the CR123 in series.

There are some true horror stories out there from people who have suffered chemical burns and permanent lung damage, even hydrogen fluoride poisoning just from operating those normally, with a manufacturing fault in one of the cells.

I'm so glad this is ACTUALLY an article about flashlights and not some hip new product called Flashlight... Risky click there.

It's sites like this that make me love the Internet.

A few months ago I looked to buy a new flashlight and was shocked at how many choices there are.

All I wanted was a light with two modes - on and off. Maybe a low-light mode for insane battery life in a prolonged emergency. I wanted it to run on batteries I can find in a gas station. I went into the rabbit hole and never actually bought anything. I started to make a spreadsheet with all the options and features then wondered what the hell I was doing and gave up.

Yup, This is true of both flashlights and pocket knives. It's incredible how far both have come from simple devices to all sorts of features/materials/etc.

It's hard to go wrong with most modern LED lights, something that takes 2x AA sounds like a good fit for what you want. I've been a fan of Fenix and Eagletac both have held up well over a few years of hard use.

Buy a handful of these ones:

https://m.aliexpress.com/item/32584791011.html

$1.80 a piece (with free shipping), takes 3 AAA batteries, good light (but probably just 1/10th of the "2000 lumen" claimed), useful zoom function, resonable size, lasts for 3-4 hours on a set of batteries in max-light mode, probably twice in low-light mode.

I've had several over the last few years. They are not super durable, but for a general purpose flashlight, at that price it's perfect.

but probably just 1/10th of the "2000 lumen" claimed

So they never even tried to measure the output, huh? :-) I've got a 900 lumen headlamp I use for trail running. It cost $200. There's a 1200 lumen version, but it's big enough that I wouldn't want to wear it on my head. 2000 lumens and we start to get into "driving lights you see on the front of a car". I'm confident that you know this, but wanted to back up your statement with some comparisons and to demonstrate you are not being hyperbolic when you say that (in fact, I'd question even 200 lumens).

Regardless of the questionable specs, for $2 you could sprinkle these liberally where ever you might need light. Might get a few myself.

These are the same Asian vendors who proudly sell "6000 mAh" 18650 cell batteries, even though no battery chemistry on Earth could get you that energy density. They know it's much less than 2000 lumen, but they don't give a crap about the factual accuracy of the specs. And I think most people who are savvy enough to buy from these sites quickly catch up and learn to divide by 2 or 4 or 10.

Amazon, OTOH, has a bigger problem in this regard since everyone buys stuff there. Fortunately Amazon has a much better reviews/ratings system.

All I wanted was a light with two modes - on and off.

If you're in the U. S., go to Harbor Freight's website and print off the "free flashlight" coupon (I just looked, and harborfreight.com has it at the top of the page). Go buy some tools. Or just go pay the full $3 for their LED flashlight. I've probably got three or four of these things rattling around. One of them rattled around in my motorcycle tank bag for two weeks going as far north in Alaska as is possible on a bike, bouncing down every dirt road I could find. Still use that one today. Several are years old and get used for camping and around-the-house, still going on their original batteries. Bright enough for most of the times you need a flashlight. Runs on AAs. If I ride off with it sitting on top of a saddlebag, I shed no tears.

If I need serious lighting, I break out the high-dollar 900 lumen headlamp. But most of the time I find myself reaching for the cheapy HF that has never failed to turn on and apparently runs on perpetual motion.

I've got a couple of these from Harbor Freight as well. During our last home repair project, we wound up needing just a little extra daylight, which of course we could not have, but my wife had printed off two of those coupons before we went in for supplies; she used one and I used one. The flashlights we got are designed to be able to be hung up on something to provide a bit of spot lighting without needing to be held, and they put out a surprising amount of light. They did the trick and we were able to wrap up our repair after sundown.

10/10, hard to beat a useful, quality flashlight for free.

Ha, this cracks me up. Been there for sure.

I find it increasingly difficult to find flashlights that don't four or five modes of operation, especially bright ones that use 16450 (or is it 18450?) batteries. And they all seem to have slightly dodgy switches that change the mode with the slightest touch.

Brightness and barrel construction are all great, but please just give me an on/off light with a solid switch!

I just checked Wirecutter because I thought if any place is going to recommend one specific light, that would be it. Unfortunately, flashlights don't seem to be on their radar.

Visit Candlepower Forums (http://www.candlepowerforums.com/vb/content.php). More than you ever wanted to know about LED flashlights.

My personal recommendation would be FourSevens' Quark Click (http://www.foursevens.com/products/QK2A-X-AE-24). Takes 2 AAs, outputs 336 lumens, and has very solid construction.

My first visit to Candlepower is what caused me to start a spreadsheet. It is indeed more than I want to know.

That flashlight looks exactly like what I'm looking for. Thanks!

The problem is that once you get past a few hundred lumens, "on/off" doesn't really work well. I have a small Nitecore flashlight with a since cell in it and it puts out 850 lumens on maximum. That's too much to read a book at night with, yet it's great for finding a lost dog in the woods.

Off - low - high is fine.

I don't want strobe, I don't want morse code, I don't need five brightness levels.

My number 1 rule for buying a flashlight: Never buy a flashlight made by a battery manufacturer.

It certainly seems like a basic/simple topic but it is hard to see what other branches you could have covered except maybe laser diodes. Would you put those in a separate category or they could be considered as a flashlight with a very narrow beam?

NSFW Warning: Had a popup appear with nsfw content on it.

A thread just on top of the flashlight one is "When Pseudosex Is Better Than the Real Thing" – I thought "oh it must be sex stuff trend on HN today"

This web page froze my web browser due to the multiple tracking domains it loads. I flagged this.

It also contains a link to the tracking dashboard that leaks all analytics. It's the "http://extremetracking.com/<redacted>" link at the very bottom of the source. Among others, it lists visitor IPs and referrers. That information really should not be public. But honestly, I wouldn't have noticed without your comment - uBlock Origin prevented loading of the tracker.

Seeing this makes mi nostalgic. That tracker was insanely popular in the time before Google Analytics existed.

Back then privacy was not an issue, just by being on the internet you were the weird one :)

I just checked, their domain name is 17 years and 9 months old.

How does it determine the search engine queries leading to the page?

Note: This web page is about electric torches. Might be good to change the title?

Well, the title of the page is "Basic Flashlight Tutorial", so it matches as-is.

Of course, Electric Torch is UK terminology (may be used elsewhere that I'm unaware of) However, Flashlight is used in the US/Canada.

Electric Torch sounds awesome, like something from a D&D guide. I'm going to try to use that next time I ask my wife where the flashlight is. On an iPhone in the UK is the flashlight button labelled electric torch?

We call them personalTelephones here, old chap.

You call the Flashlight app, "personalTelephones"?

iPhones => personalTelephones

i => personal

Phones => Telephones

It's a joke based on British formal speech

I get that. They were responding to what they call the Flashlight App on the iPhone.

My Android has a button labelled "Torch". It doesn't set itself on fire when I toggle it, so I'm happy enough.

No-one here says 'Electric Torch' (especially not with Caps). They say 'torch' and, as far as I'm aware, 'flashlight' is a perfectly valid term for what this article refers to, so perhaps the GP is being humorous.

As a native-born American, I would have no problem with a headline from The Guardian talking about the basics of using a torch. I would briefly wonder if they're referring to the electric things that make light, or the flamey things you hold in your hand, and shortly after conclude that of course they mean "flashlight".

But unlike "torch" as far as I know "flashlight" has a single meaning. Were you truly confused by the headline, or just being pedantic?

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