Idea - Page 1
Forum section: electronics / projects

author: neo
author_rank: Super Contributor
timestamp: October 02, 2016, 05:09:11 am
content: i saw this flashlight charger in a game (see below) could i do anything close to it in real life with a car battery and a gear motor or something

author: mariush
author_rank: Super Contributor
timestamp: October 02, 2016, 06:06:15 am
content: The lever has a spring inside, which makes it return to the default position after its pressed. When you press it, a gear (wheel with teeth) rotates in one direction, which rotate other gears so with just a tiny squeeze, you get a lot of spin on the motor (the big thing to the left). The motor has permanent magnets and windings so when the inside axle rotates, you get electricity which you dump into a battery. Some use a supercapacitor and then there's a circuit which takes the energy from supercapacitor to dump it into a battery.The mechanism in the game is not that realistic, in real life you'd have to squeeze that thing a lot to get that much light for so much time. It's more efficient to rotate a lever at a constant speed (easy on the hand, slow, the gears inside make the motor spin fast) for a minute or so, and there's plenty of such charging solutions... i saw one just the other day in this video (jump to around 7:50 ) :http://www.newegg.com/Product/Product.aspx?Item=N82E16813130924

author: neo
author_rank: Super Contributor
timestamp: October 02, 2016, 08:05:28 am
content: thats a newegg link, and while it may not be practical can it be built out of an old ac motor, or the like? if for nothing else novelty

author: ebclr
author_rank: Super Contributor
timestamp: October 02, 2016, 09:00:23 am
content: https://www.amazon.com/Emergency-Generator-Portable-Electronics-Including/dp/B00CTDW5TA/ref=sr_1_2?ie=UTF8&qid=1475398786&sr=8-2&keywords=hand+generator

author: Buriedcode
author_rank: Super Contributor
timestamp: October 02, 2016, 09:45:12 am
content: Gotta love Metro 2033. Excellent game.Thats a rather 'steam punk' hand generator - the whole point of metro 2033. As you mentioned in your previous threads, you are young, and it seems eager to build stuff. But I think it would be a good idea for you to get to grips with 'reality' first. Thats not to say you can't make cool stuff, or 'nothing works like it does in games and movies', just that it helps to do back-of-the-envelope calculations,Research how how different battery chemistries are charged, do they require constant voltage? constant current? Can you 'push' a lot of energy in a short space of time? and what limits there are to the total power you can 'push' in? Once you get a handle on that, working with watts and joules you can get an idea of how much effort, what size of generator, and gearing you'll need to make a charger thats actually useful - and not something where you spend 15 minutes cranking something only to get a bulb to light up for 3 minutes.Also as that generator was quite nicely done (the game designers did a good job) you can see laminated iron and coils so it looks like it was made from a large dynamo or alternator - if you were to completely build that it would be heavy as sin. Certainly not something you could just 'carry around' to charge your phoneWith that said, often in games characters can carry around lots of ammunition and guns weighing tens of kilo's - but we wouldn't play them if you could only carry 50kg of gear.

author: neo
author_rank: Super Contributor
timestamp: October 02, 2016, 07:59:34 pm
content: if i did do something this crazy it would be no crazier than turning a 30 pound car battery and old car headlight into a flashlight, certainly not the most useful but when you really need light you would have it, as i said idea just so i could get my grips as to whether it was possible or just made up

author: CatalinaWOW
author_rank: Super Contributor
timestamp: October 05, 2016, 04:28:47 am
content: The simple answer to your question is YES, you can do it. But as others have pointed out, it won't be as rewarding as you like.A simple back of the envelope calculation can show you why. Car batteries have capacities that are measured in a few tens of amp-hours. You can google the battery that you have to find the exact value, but it may take a bit of looking. Here in the US batteries are specified in things like cold cranking amps and things like that instead of capacity.Ignoring efficiency of charging, and assuming 20 Amp-hours you would have to put 20 Amps into this battery for an hour to charge it. At roughly 12 volts, that means you are supplying 240 watts for that hour. Which is what a fairly good bicyclist can supply using the major muscles of the legs over that period of time. Most of us lab jockeys can't quite do that. And literally no one in the world can do it squeezing a hand clamp.Now maybe this project would be interesting if you set up an exercise bike as the generator and then got Mom, Dad and any sisters and brothers on a fitness craze. They get their exercise and you get your flashlight charged.

author: calexanian
author_rank: Super Contributor
timestamp: October 05, 2016, 05:44:26 am
content: Quote from: ebclr on October 02, 2016, 09:00:23 amThat thing must be a bear to crank. People don't realize how much effort goes into a few watts. A walking human is only utilizing 25 watts or so and thats exerted by your legs. Imagine 10 watts using just your arms and hands on such a small diameter lever.

author: CatalinaWOW
author_rank: Super Contributor
timestamp: October 06, 2016, 12:12:52 am
content: Just for reference, the record power output over a one hour interval is 430 watts.Typical pro bicyclists can sustain 250-300 watts over a one hour period.Normal fitness junkies typically fall in the 100-250 watt output when sustained for an hour.The run of the mill couch potato is down in the 15 to 75 watt regime.The wide range shows how much is possible within human variation. There is probably some genetic freak couch potato out there, who after years of training on Cheetos and TV can produce 200+ watts. And there are people who work out every day and struggle to bust 100 watts.

author: Cyberdragon
author_rank: Super Contributor
timestamp: October 06, 2016, 03:42:39 am
content: Quote from: Buriedcode on October 02, 2016, 09:45:12 amMythbusters actually tested this. Soldiers can actually carry that much junk around. I'm pretty sure someone who can carry that much stuff would have no problem carrying that light and cranking it.You on the other hand...hit the gym much? Otherwise you're in for a hernia.

author: neo
author_rank: Super Contributor
timestamp: October 06, 2016, 03:57:01 am
content: i life 50 pound sacks of feed regularly, i dont need no gym, as for the whole practicality of the flashlight the way i want to do it would only require 60 watts per hour so it would be sufficient as an emergency flashlight, but all this is theories

author: vk6zgo
author_rank: Super Contributor
timestamp: October 06, 2016, 07:18:57 am
content: Why charge anything?Torches (flashlights)which work by continuously squeezing a lever have been around,on & off,for 100 years or so.With LEDS,it would be possible to make one where the wrist action would be much less tiring than the incandescent globe versions.

author: neo
author_rank: Super Contributor
timestamp: October 06, 2016, 08:46:25 am
content: because i happen to have a flashlight made from a car headlight and i just wanted to know if this was possible and maybe get a few ideas, but really this is getting to be quite the debate

author: mariush
author_rank: Super Contributor
timestamp: October 06, 2016, 10:40:55 am
content: With the Metro 2033 franchise, it's further unrealistic because they're living underground, in a world affected by radiation, so they're eating pig meat (if they're lucky and rich, not all could afford if i remember correctly) and maybe rats and whatever grows in wet underground and tolerant to radiation (moss and crap on walls) ... so they don't eat very well, and they don't look muscular and strong enough to carry tens of kilos on their backs. They also carry several weapons and ammo and use bullets as currency..It would have been more realistic for the character to have a big 7Ah motorcycle battery in the backpack (weighing 3-5 kilos) that can be charged/replaced for a few bullets at a station and would last for something like 20-30% of the time between stations (so you'd have to be careful how long you use it), and an optional much weaker flashlight (maybe led based but not sure leds were common in the time the action happens in metro) which could be charged with light charger or by shaking or winding something for a few seconds and then last for a minute or so in the game.

author: neo
author_rank: Super Contributor
timestamp: October 06, 2016, 11:08:26 am
content: i like your thinking but you can't blame Dmitry Glukhovsky too much, he didnt even mean to write a book to begin with it was a thought experiment that transitioned into a book and then one step further from reality is the game. I will admit that despite their flights of fancy sometimes they are amazing works of art in their own right, the book ive read twice and still am finding new layers. But thats just my opinion, also further opinions on the matter, leds were in russia in 2005 (book writing date) and definitely by 2013 (the year of the war in the book) though much more likely underground would be vacuum fluorescent displays because of the nature of the tunnels it could be far more easily believable that there would be a large stockpile of them than leds, as leds would be newer and stored in more conventional warehouses, but again this is just my opinion on the types of light sources they might have available