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Hello /diy/,
I have a basic understanding of electricity but need some help. I am purchasing some solar cells that each have 2.8 watt, .5 volt output. What could I do to change that to 5 volt 1 amp? This is a project for making a solar powered USB charger.
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>>944254
5 volts at one amp is 5 watts
2.8 watts is less than 5 watts
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>>944254
Buy more cells.
Arrange series/parallel until you achieve 5 watts output.
???
buy something useful.
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I will have multiple and over 5watt< output
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I have a problem with concrete, i made some pillar foundations for fence with old cement and i think its not maturing at all, its been 2 days and is still dark i color and sandy. Is it fucked or is there still a chance for it to get hard ?
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>>943993
takes a month to harden
you are talking about green concrete. its like that.
by sandy do you mean if you step on it you leave a boot print or you can scratch it like kids do to sidewalks?
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>>944034
It shouldn't take longer than a day. If it's taking a month to harden there's not enough cement in your mix. I'd only expect longer than a day or two at most if you were using flux additive or a dry mix with a large sand to cement ratio.
Proper ready mixed post-crete is hard within half an hour of pouring.
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>>944034
you are confusing harden and cure
hello /diy/
i have old dr martens boots and i want to do something similar to pic related to them (pic 1 or 2, haven't decided yet)
so can you tell me what is the best way to do that, which materials/techniques to use?
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>>941759
OP here, forgot to mention (just in case it isn't obvious from the pic)- i want to remove leather from steel caps
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>>941759
Probably not a good idea for many reasons but if you must just cut the leather and then add some superglue or something to the edges.
Why would you even need to ask this here
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>>941759
Just use a razor blade and some polish
Should work OK
Recently acquired the shell of an two old cf-25 toughbooks. Thought i would gut, install new screen,
keyboard and raspberry pi, with the goal of mobile
computing.
Any suggestions for additional hardware that would be interesting/useful to integrate? only suggestion I've had so far has been a headphone amp/DAC for audio out.
What other cool stuff could I cram in there. There's heaps of spare real estate, all I have factored to fit so far is the rpi and its connectivity addons, li-po battery, charging circuit, new keyboard, a 15' LCD from a newer laptop.. and that's about it.
Have access to a 3D printer if that's any inspiration
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Wrong pic, it's this model with the large bezel
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>>942315
I would maybe suggest a Novena instead of rpi, it's actually almost designed for what you are trying to do. Might need to look at the dimensions etc, but it would be far more flexible and useful than a pi.
https://www.crowdsupply.com/sutajio-kosagi/novena
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>>942326
>https://www.crowdsupply.com/sutajio-kosagi/novena
Raspberry pi $30 dollars
This shit, $550
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How to get rid of ice dams?
I went on vacation for a week and while I was gone, there was a lot of weird weather, so now I have ice dams. I've thrown RoofMelt up there and scraped as much off as I could. Would it be too late to get the heated cables at this point? Any other suggestions?
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Vent your roof properly and use don't use wadded up timbit wrappers for insulation in your igloo.
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>>944612
I would say toss up more salt, but make sure it's properly temperature rated (regular rock salt isn't doing shit if you're sitting at like -15 F, for instance)...but I don't know how that shit reacts with stuff like wood/whatever kind of roofing you have.
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>>944616
I just bought this house about 14 months ago, so I'm still learning its quirks. Though, I never had a problem last winter.
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What are the advantages of leaving the thermostat on auto or on fan
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>>943865
auto turns the fan on when the heater is heating the house
fan just leaves it on all the time
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>>943865
I leave the fan on because it filters the air in the house. We get terrible inversions here so I keep HEPA filters in the furnace.
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>>943869
So does it run while the heater is running and when it's not?
Anonymous
Raspberry Pi Power Supply 2016-02-08 02:06:48 Post No.943283
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Raspberry Pi Power Supply 2016-02-08 02:06:48 Post No.943283
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Hey guys I am building my own raspberry pi portable for emulation and need help with power supply.
I have pic related as my PSU and it gives me approx 2 hours of run time. I want to increase the capacity of the battery so I am buying another one and am going to strip the second battery from the charging circuit and hook it up in parallel with the first battery.
My question is, is it safe to do so and would it work? Will there be any issues with the charging circuit or the way its going to function?
Thanks
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>>943283
it might work, but cells have to be balanced to charge correctly. You probably want a 2-3 cell balanced pack. There are also cheapo chinese 10Ah supplies for cheap, which are also a good deal.
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>>943287
Hmm okay, what do you mean by 2 - 3 cell balanced pack? I don't know a lot about electronics.
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>>943289
see that 18650 (the battery there)? they store a lot of energy but that means that while you can't say drop a battery and it will combust, overcharging (causing a breakdown of the lion barrier) is a real risk.
If two cells aren't balanced, one could say get 2 A while the other got .1 A, and if the max charge of that cell was 1.5 A, then you'd have a problem.
Honestly lion battery packs are so cheap you can get a good one from amazon for really cheap rather than building one yourself because of the economies of scale.
My electric dryer isn't getting hot enough. It's probably the heating element, this one is like $25 to replace BUT I have another new HE for a different dryer that does fit and looks almost the same but is a different model number.
How safe would running a different heating element be?
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If it gets warm when you first start it up its probably not the heating element. The exhaust vent could be clogged causing the hi limit to cut off the heat. Check that first, turn the dryer on and go outside and check where it blows out. If it's not blowing out strong that's your problem.
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>>944641
I cleaned it out about 6 months ago and the vent is spotless, the air push is strong.
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Post the model numbers. I'll let you know.
Hey /diy/ relative newcomer here. I'm interested in robots/drones and robot/drone accessories. Specifically I wanted to purchase a 3D printer and make the robots myself. What are the best places for the cameras and guts and such? There are a lot of places that sell these things but I was wondering what you guys recommend. I was going to make a cat toy as my first project. It would be a little RC bird/mouse hybrid thing capable of flying and driving around the house and obviously be durable enough to resist the kittys claws and teeth. Probably won't happen for a while but will post results if I ever get my life on track and can afford this hobby.
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>>944526
Before you start fucking around with money for 3D printers, I would recommend getting an arduino kit and starting off with small simple projects. Also, I would reconsider trying to make a robot toy for a cat, seems like a waste of money in broken parts and materials.
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>>944531
Arduino looks like cool shit, would definitely learn a lot.
As for the cat toy, I would just use it as a learning experience. And I would find out if I really wanted to continue down the path of making robots. Plus I want a 3D printer period. Shit is just plain cool and I'm sure there are things I'd want to do with it I haven't even thought of yet.
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>>944537
3d printers are awesome. I have a printrbot simple and a velleman k8200. You'll love it but it's not plug and play shit. There's a steep learning curve.
Anyway, I suggest you start from a project such as Polargraph (Google it). Limited moving parts, and you can code your own driving software as an exercise.
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tl;dr: Any suggestions on leaded solder that doesn't smell like shit?
I've been using the roll of solder on the right for basically my whole life. My dad used the same stuff growing up, and he gave this to me when I moved out; it has to be at least 20 years old. Maybe it's just because I grew up with it, but the smoke actually smells pretty good.
I ran out recently and started using the roll on the left. It works fine, but it smells fucking awful. I start getting headaches if I solder for too long. I should probably set up a solder fume extractor even for the old one, but I'd like to find a replacement that smells closer to the old roll.
Presumably it's the flux core that determines the smell. I don't know what kind of flux the old roll used, my pic is all that's left of the label. I'd guess it's rosin core based on how hard it is to clean the flux off. The small picture in the lower right seems to be what the label looked like when it was new, but who knows what the specs were.
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>>942720
Rosin core solder is exactly what it is, pine tree sap. I have tons of old solder nothing works better.
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>>942726
And pretty much all rosin smells decent, or is there a lot of variation for some reason?
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>>942720
old flux: gives you cancer, smells nice
new flux: gives you cancer, smells awful so you don't smell it anymore
the lead won't hurt you but the vaporized organics will anon
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Hey guys,
Quick electrical question.
I have a 220v outlet with a 30 amp breaker. Can I plug a 220-110 step down transformer to the the 220v outlet and run more than 30 amps on 110v?
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half the voltage, double the current. so, yes.
problem is finding a 60A 110V x-former, it's gonna be huge and expensive.
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There's site transformers like this that are 10kVa and output 2x32amp or 4x16amp
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>>944512
You could use more than one step down transformer though
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Hey guys, I've got a weird question and don't know where to ask it...
I am thinking about greenhouses, and I've decided the gothic arch style is best. It provides a ton of headroom though, so you could add a second level. But then some plants might get smothered. Is there some kind of "one way coating" that would bounce more sunlight across? That way it lets light it and reflects it a little.
Then I started thinking about underground greenhouses.... could you use a series of magnifying glasses to concentrate sunlight down a series of mirrors and reflect it across an entire underground greenhouse?
Doesn't something like this exist already?
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makes a change from shipping containers, ah spose..
http://www.thelowline.org/get-involved/lowline-lab/
- above is non-informational-tier (cant be bothered finding a good link specific to your interest) - but, google them a bit, prob. find some stuff.
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oy mate - i know that there is a way they bring light down the underground in berlin with those tubes, i know its on a big plaza, but can't remember on which one.
pic related, these are those tubes
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>>942671
kek, i am such a faggot.
Berlin. Potzdamer Platz. They bring light to the underground station with this.
Hello, /diy/, I have a question for you.
Recently I've been reading about tendon-driven manipulators, and I want to build one for fun and learning. I think I got the idea for the arm and ropes itself, my question is about motors. What should I use? Servos, stepper motors, dc motors? Or maybe long-ass linear actuators? My goal would be to create something strong enough that it could beat an average human in arm wrestling. Assuming that whole thing does not break, how can I achieve required torque/force as cheaply as possible? I'm a student living in Poland, so delivery fees and tight budget kinda screw me over.
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>>942484
The strongest thing you could realistically get is hydraulic servos. Naturally, these are complex and expensive. But ANYTHING you can use to pull the tendons will work. Cheapest practical option is probably going to be a geared stepper motor.
That being said, unless you kind of cheat a little (and use different kinematics than the human arm) or greatly limit the capabilities of your machine such that all it can really do is arm wrestle, you are never going to beat a human in a strength contest on a budget. Animals are insanely strong for their size.
On another note, I would suggest UHMW (often referred to as Spectra/Dyneema) for the tendons. Cheap, low-stretch, and very strong.
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>>942520
Thanks for the UHMW tip, definitely going to try that. Hydraulics are probably out of my reach, will look into stepper motors. As I was poking around the Internet some more I found this video
https://youtu.be/ESFewdU0JcA
Guy uses one drill motor set on high torque/low rpm to lift himself off the ground on a rope. And poking some more I found that quite a lot of people are selling old drills cheaply. Usually something about them is broken, but I guess I could try to repair it and salvage the motors? Of course that would need addition of encoders for precision, but could it work?
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>>942532
You don't even need to buy broken ones, there's tons of em on Craigslist. Or you could find just the motors on eBay or something.
Anonymous
Potassium nitrate rocket fuel 2016-02-07 01:44:31 Post No.942687
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Potassium nitrate rocket fuel 2016-02-07 01:44:31 Post No.942687
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Potassium nitrate rocket fuel
Anonymous
2016-02-07 01:44:31
Post No. 942687
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Has anyone ever made any oh this stuff? Also I can't find the proper temperature in which to cook it and it keeps igniting while I'm cooking.
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may i suggest a 1:1 Sulphur/Zinc mixture?
easy as hell to make, just put 1kg zinc powder and 1kg sulphur powder into a barrel, add a few 25mm steel ball bearings and roll the barrel around for a while till you get a uniform colour.
no heat required therefore far more stable.
ignition temp is 1200 C.
a 100 Ohm resistor will flash at the required temp if hooked up to a standard 12v car battery
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>>942709
interesting, I may have to give it a try. One of my biggest problems is that the fuel doesn't give off much thrust Just lots of smoke and noise. What am i doing wrong?
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>>942709
>ball mill
>full of fucking rocket fuel
>steel tumbling media
Oh shit nigger what are you doing?
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So, I just picked up a used Lexus LS 430. I already love it to death, but it does have some character. Little paint scuffs, but no dents or loose parts. All of that I can live with, but this steering wheel bugs me. While the dash has been cared for, the wheel is cracked all over from sun damage. I can live with the look, but I can feel the ridges when I drive.
If it's actually wood, I could do something about it. The problem is that I have no clue. Anyone ever try to restore these before?
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>>944555
>I can live with the look, but I can feel the ridges when I drive
Just close your eyes and imagine you are holding onto a hard thick veiny one.
Otherwise, follow the age-old wisdom: don't be a fool, wrap your tool. Pic related.
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>>944558
That is how people die.
Who the fuck thought that shit is a good idea
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Just buy a new one
http://m.ebay.com/itm/LEXUS-LS430-LS-430-02-03-04-STEERING-WHEEL-BLACK-LEATHER-AND-WOOD-GRAIN-/111824804365?nav=SEARCH