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File: 1424031455546.jpg (530.51 KB, 1005x1320, 67:88, battery drill motor.jpg)

Motors and circuits 02/15/15 (Sun) 20:17:35 No.1682 [Reply]

Hi /sci/, I'd like to use the motor from this battery drill for something but I'd like to power it with a PC's PSU.

The battery says it's 12V at 1.2 Ah

The label on the power supply says 12+ at 12A

Am I right in thinking that to make this work all I need is to connect the Positive and Negative wires to the points the battery was touching but with a calculated resistor on the negative side to control the current? And put a switch on the positive side?

I've used Ohms law before but not in real life, I've no idea what I'm calculating or doing.

Also, can anyone explain what the iron circles with coiled wire are doing?

2 posts and 1 image reply omitted. Click reply to view.

02/16/15 (Mon) 03:32:36 No.1692

>>1691
>So literally the only thing I have to do is solder the positive/negative 12V wires from the PSU to the positive/negative clips on the circuit

Did this and it worked.

Because it was so simple I now want to fit all sorts of crap to my PC.

02/17/15 (Tue) 17:31:05 No.1698

>can anyone explain what the iron circles with coiled wire are doing?
They're (fairly small) inductors. Usually you see those on data cables (ferrite beads) to reduce high frequency interference. In this case I'm guessing they're there to limit inrush current, probably to extend the life of the motor. That's kind of unusual.

02/18/15 (Wed) 01:31:28 No.1703

File: 1424223088735.jpg (27.34 KB, 341x320, 341:320, Ohm's_law_formula_wheel-.JPG)

>>1698

A battery drill has the risk of having the chuck jammed in position during use while full voltage is still being applied. What is happening?
I asked you the above question but started to try answering it myself

Using basic electrical equations

While we don't know the load of the motor in numbers, the relationship of the values is quickly apparent.
Let R = 10 ohms

Voltage = 12
I = V/R
I = 12 / 10
I = 1.2 amps

Post too long. Click here to view the full text.

02/18/15 (Wed) 01:44:30 No.1704

>>1698

Oh and thanks for your answer.

My train of thought is at odds with "inrush current"

I know that it's more difficult to start a motor than it is to keep it at a constant speed. It made sense to me that a larger current is required to start it.

At a high load, resistance is high and current is low. We can boost the voltage to raise the current but the high load is going to result in heat building up.

As rotational speed increases, load decreases, current increases. Voltage needs to drop to hold rpm at operational speed, lower voltage means a lower (operational) current.

>more thinking out loud

02/18/15 (Wed) 17:15:02 No.1711

>>1704
>It made sense to me that a larger current is required to start it.
You definitely need more current to start, but you might not want it too large because it may cause the commutator to spark. That can damage the commutator and brushes.
However, now that I've thought about it, it seems more likely that it's there to smooth out power when running (it forms a low pass filter with the little capacitors) or maybe for emissions compliance (FCC or local equivalent.)

File: 1423395973198.png (1.08 KB, 96x96, 1:1, window.PNG)

02/08/15 (Sun) 11:46:13 No.1590 [Reply]

/med/ is ded, so I'm asking you fine fellows.

1. I grew up around cats. Should I get treated for a probable latent toxoplasmosis infection? Will that improve my mental environment?

2. Modafinil. Should I?

02/08/15 (Sun) 11:47:56 No.1591

If the "providing health advice" idea tastes bad, just interpret it as inferring individual outcomes from statistics.

02/09/15 (Mon) 04:55:35 No.1599

1. Can't you get a test to see if you actually have an infection? I've never heard of any mental benefits to curing it, and won't you get reinfected after you cure it?

2. https://en.wikipedia.org/wiki/Modafinil#Adverse_effects

02/18/15 (Wed) 07:11:17 No.1708

>>1599
>I've never heard of any mental benefits to curing it

I'm thinking of the whole schizophrenia angle.

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Another SpaceX Launch and Hopeful Landing 02/08/15 (Sun) 22:39:10 No.1595 [Reply]

Should have made this thread days ago.

In about half an hour (6:10 PM EST) SpaceX will launch the DSCOVR space and earth weather satellite to Earth-Sun L1, and try to land the first stage of the Falcon 9 on the drone transport ship again.

NASA TV's website will stream it so no worries there.

18 posts and 10 image replies omitted. Click reply to view.

02/12/15 (Thu) 14:00:06 No.1647

File: 1423749606058.jpg (60.16 KB, 1038x626, 519:313, tank.JPG)

Can someone tell me what I see here?

Is it just a camera inside the tank of the rocket? Whats its purpose other than seeing how much fuel is left?

02/12/15 (Thu) 17:16:03 No.1649

>>1647

It does little towards letting them know how much is left.

I don't know their official reasoning but I'd say it's there because they can and it gives an interesting insight of how fluids behave in microgravity.

02/13/15 (Fri) 14:49:24 No.1657

>>1647
In testing it's often done to check for vortex forming, using it in flight lets them check for vortex forming under varying G load.

02/16/15 (Mon) 23:31:30 No.1695

>>1657
Wouldn't some kind of baffel inside the tank make it impossible for a vortex to form?

02/17/15 (Tue) 00:59:23 No.1696

>>1695
Yes but they make it as small and light as possible like everything else in rocketry so they need to check if they removed too much.

YouTube embed. Click thumbnail to play.

02/10/15 (Tue) 01:54:19 No.1606 [Reply]

The future is now.

02/11/15 (Wed) 01:21:08 No.1618

now imagine an army of these motherfuckers parading throw down town iraq, shooting anyone on sight

02/11/15 (Wed) 02:51:34 No.1620

File: 1423623094867.jpg (10.36 KB, 250x244, 125:122, 1414848591245.jpg)

>>1618
the american dream

02/16/15 (Mon) 00:26:23 No.1688

YouTube embed. Click thumbnail to play.

maybe not quite as awesome as OPs but cool too

File: 1419040595601.jpg (28.78 KB, 324x500, 81:125, 520d8ca2929dddfa942d90d00b….jpg)

George Boole & Immanuel Kant 12/20/14 (Sat) 01:56:35 No.1035 [Reply]

This does not make sense:
http://libgen.org/book/index.php?md5=520D8CA2929DDDFA942D90D00B5C721A
(libgen.org is the best website to get books. It is the best website I have came across in a long time.)

All Ys are Xs, y=vx
No Zs are Ys, 0=zy
0=vzx, therefore some Ys are not Zs. In other words, "The majority of Ys are Zs."
Isn't that contradictory?
Why is there a "v," (does it represent some #?), and does "0=zy" mean either z or y is a zero?

Also, question to those familiar with Immanuel Kant's ideas, namely, his book, "The Critique of Pure Reason."
http://en.wikipedia.org/wiki/Critique_of_Pure_Reason
Why does it matter that mathmatics is both a priori and a posteriori?

12/20/14 (Sat) 08:54:36 No.1036

>therefore some Ys are not Zs. In other words, "The majority of Ys are Zs."
That's not right. "Some As are Bs" is simply not the same thing as "Most As are not Bs" mathematically. So just throw that out the window. "Some As are Bs" would mean that there exists at least one A that is a B, saying absolutely nothing about other As or Bs.

Have you actually read the book? Starting on page 22 it discusses the notation and what the equations mean.

02/15/15 (Sun) 16:07:30 No.1673

Off and on I've been reading Russell's "Introduction to Mathematical Philosophy", in which he describes Frege's arithmetization of mathematics, and in which he logicizes mathematics into set theory.

After I'm done with that, I was thinking of moving on to a book on ZFC, but I've heard that it's outdated by about 50 years.

File: 1423945283394.jpg (3.73 MB, 4752x3168, 3:2, IMG_7215.JPG)

Med school in Europe 02/14/15 (Sat) 20:21:23 No.1668 [Reply]

hello /sci/, I have a question for you.
I'm a junior in high school and am moving to Europe because of family problems. I'm an EU citizen and learn languages easily. Where is the best country for studying medicine and then getting a job as a university professor? I don't want to end up broke or without an MD.

02/15/15 (Sun) 01:08:28 No.1669

>Implying Yurop still has money to pay you after you graduate

02/15/15 (Sun) 03:05:07 No.1670

>>1669
that's exacly what I'm worried about! I'm thinking that I can get a medical license that also works in the USA and maybe then work in the States. Would that work?

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02/14/15 (Sat) 01:22:45 No.1659 [Reply]

jesus christ this board is pushed down
/sci/, I have a question.
I'm sure you're all familiar with the concept that the existence of constantly-moving quantum particles takes away our sense of free will, and the paths of the particles essentially pre-define the course of, well, everything. (If not, see en.wikipedia.org/wiki/Determinism#Quantum_realm)

So why does everything make sense?
If I think the number "42" and write it on a piece of paper, is it just coincidence that the particles passing through my brain to form the neural signals and the particles in my hand, paper, ink, etc. all coincide to form the number 42?
Perhaps we just live in a universe that makes sense, and an alternate one would have truly random happenings?
When a symphony plays Beethoven's ninth, is it just coincidence that the particles passing through the air pulse the same way the did 200 years prior?

02/14/15 (Sat) 11:53:34 No.1661

A coin flip is not a dice roll. The mere fact that there is randomness does not mean there are no patterns or limits. The laws that determine the probability of outcomes are always constant.

Quantum mechanics means many things have a chance of happening for each particle. The world we see is made up of so many quantum particles that the distribution of behaviour often matches the distribution of probabilities, thus behaviour is accurately describable by deterministic laws.

Because laws are deterministic in many areas relevant to species survival (gravity, heat, mechanics of locomotion, stoichiometry, etc.), and because there are enough animals in each population and enough species in the world that evolution is also deterministic, animal brains evolved to become deterministic.

02/14/15 (Sat) 15:09:23 No.1666

Are you asking why causality exists, ie. why an event can influence other events?

Your examples are stated in a slightly convoluted manner, but I think the general answer is that the particles move in that way because in those cirumstances that just happens to be the accessibly energy minimum. Why all things in nature try to minimize energy is unclear, but the fact is that they do. In cases where deliberate human action is involved, the circumstances are also explicitly set up to create this "energy trough" in such a way that it encourages desirable action (ie. the symphony, the number 42).

File: 1423662668497-0.png (337.29 KB, 387x644, 387:644, faiza.png)

02/11/15 (Wed) 13:51:08 No.1631 [Reply]

So this is the succubus that ruined Walter Lewin?

https://archive.today/9CciG

Well, to be sure, it wasn't some "offhand remark" that did him in, apparently he has been making at least a dozen students send him nudes and erp.

But fear not! Even though Dr. Lewin's video lectures are gone, Ms. Harbi is making some of her own to carry the torch: http://www.fixyt.com/watch?v=K3z4ZGTPPwg

02/11/15 (Wed) 17:30:40 No.1632

>Making them

Yeah, I'm he made them do it.

Fucking sluts

02/11/15 (Wed) 21:34:44 No.1635

>making
Lewin has mind control powers?!?

02/12/15 (Thu) 18:53:38 No.1650

>>1635

Physics, bitch.

02/13/15 (Fri) 01:15:49 No.1653

>>1632
>>1635
He apparently has chat logs of him joining her facebook out of the blue, sending a screenshot of the instructor interface for the course, and asking for erp/nudes.

She submitted the chat logs (and possibly the 10 or so other people submitted theirs).

If the logs were fake, I suspect Lewin would have contested them during the investigation, but instead he allowed his reputation be destroyed while he is hiding in his home, incommunicado. So, I'm afraid it's true.

02/13/15 (Fri) 01:16:15 No.1654

>>1653
*she has chat logs

File: 1423592620116.png (169.74 KB, 682x778, 341:389, nature climate change.png)

02/10/15 (Tue) 18:23:40 No.1613 [Reply]

Can someone get me a research paper please? I think someone made a board for shit like this but I don't remember it.

My world class university doesn't appear to care about publications about climate change.

>Climate Change
>Science
>ishiggit 2016-6+1

http://www.nature.com/nclimate/journal/vaop/ncurrent/full/nclimate2488.html

http://phys.org/news/2015-02-electricity-biomass-carbon-capture-western.html

02/11/15 (Wed) 03:55:38 No.1621

File: 1423626938202-0.jpg (156.54 KB, 820x827, 820:827, hue.JPG)

File: 1423626938202-1.jpg (164.16 KB, 793x802, 793:802, hue2.JPG)

That would be £30, thank you.

02/11/15 (Wed) 06:33:28 No.1622

>>1621

Much funny. My feelings are sore.

You're a monster.

02/11/15 (Wed) 13:39:08 No.1630

Post an email.

Anonymous 02/12/15 (Thu) 04:00:04 No.1641

>>1630

Pls

File: 1422379709471.jpg (111.75 KB, 600x400, 3:2, cc_math_2dry_600.jpg)

01/27/15 (Tue) 17:28:29 No.1484 [Reply]

What are your ideas on encouraging children to be comfortable with mathematics?

01/27/15 (Tue) 21:15:54 No.1486

We had some exercise in 4th or 5th grade if I remember called Mad Minute, where you'd get a sheet of problems and be challenged to solved as many of them as you can in a minute. I really enjoyed that.

I suppose it probably wasn't quite so fun for the slower students however.

01/28/15 (Wed) 09:45:06 No.1490

They need to push the fact that many interesting jobs require more than basic math.
Sniper = math
Pilot = math
Architect = math
Basically find the most advanced math required for jobs lots of kids want.

02/11/15 (Wed) 12:28:59 No.1627

I'm against it. Stop pushing the 'science is cool' meme altogether. Keep retards from thinking they can be scientists.

File: 1423145450364.jpg (112.42 KB, 413x363, 413:363, xavier.jpg)

02/05/15 (Thu) 14:10:50 No.1546 [Reply]

http://www.popularmechanics.com/technology/news/a13919/new-steel-alloy-titanium/

Neosteel is now a thing. They just need to figure out how to protect it from rust.

02/05/15 (Thu) 18:38:33 No.1553

>>1546

I can tell you that titanium is a giant bitch when it comes to oxidation, I'm thinking particularly where welding is involved. You have to clean the oxide layer off, super clean (don't touch it with your "clean" filthy hands with your salts and sweats), and weld it inside an inert environment (chamber) or vacuum.

If "neosteel" brings this added difficulty to welding it will stay in the ranks of superalloys for specialist application only.

Sounds very cool though.

I realise I didn't read the article well at all. It's a Steel/Aluminium alloy with the strength and lightweightness of titanium.

I have no idea how the fuck that will weld.

Steel and Titanium weld very similar, except the Titanium is a lot more particular when it comes to cleanliness/shielding/tempering. They can both be TIG welded with a DC current.

Aluminium on the other hand typically requires TIG welding with an AC current, because of the uniform oxide layer found on the surface.
Post too long. Click here to view the full text.

02/11/15 (Wed) 12:26:34 No.1626

>>1546

are you being autistic again

File: 1423552185006.png (3.09 KB, 478x415, 478:415, help.png)

02/10/15 (Tue) 07:09:45 No.1610 [Reply]

sqaure ABCD has a side length of 1. If 2 points are chosen along AB, BC, CD, or DA, at random, what are the chances of the distance between them being 1/2 or less?

this was one of the questions on this years AMC10, and is supposed to be solved without a calculator, can someone explain how to do it?

02/10/15 (Tue) 10:00:49 No.1611

File: 1423098203978.png (106.53 KB, 1468x664, 367:166, explosive decompression.png)

02/05/15 (Thu) 01:03:24 No.1535 [Reply]

What happens when you're inside a pressure vessel at 9 atmospheres pressure and someone opens the door to 1 atmosphere?

Picture related

Holy fuck

02/05/15 (Thu) 07:59:12 No.1543

>>1535

Since no one is likely to just read all that shit

https://en.wikipedia.org/wiki/Byford_Dolphin_accident

>Coward, Lucas and Bergersen were exposed to the effects of explosive decompression and died in the positions indicated by the diagram. Subsequent investigation by forensic pathologists determined Hellevik, being exposed to the highest pressure gradient, violently exploded due to the rapid and massive expansion of internal gases. All of his thoracic and abdominal organs, and even his spine, were ejected, as were all of his limbs. Simultaneously, his remains were expelled through the narrow trunk opening left by the jammed chamber door, less than 60 centimetres (24 in) in diameter. Fragments of his body were found scattered about the rig. One part was even found lying on the rig's derrick, 10 metres (30 ft) directly above the chambers. The deaths of all four divers were most likely instantaneous.

02/05/15 (Thu) 19:32:33 No.1556

File: 1423164753272.png (50.45 KB, 952x538, 476:269, byford test.png)

>>1543
>>1535

I'm running some crude simulations in Solidworks to get an idea of what the environment inside the chambers was like.

I'm getting flow velocities easily of over 100 m/s at the doors with peaks at nearly 300m/s.

200 mph to 600 mph, and that's just the "wind".

02/07/15 (Sat) 04:17:01 No.1584

>>1556
Interesting, thanks for posting the results. I'm trying to imagine the noise of that volume of air shearing at 100-300m/s.

02/09/15 (Mon) 16:42:05 No.1601

>>1535
>>1543
damn, that's sad and pretty gruesome

I guess at least their deaths were instantaneous

File: 1422749618991.jpg (738.72 KB, 1350x1350, 1:1, rei.jpg)

02/01/15 (Sun) 00:13:39 No.1513 [Reply]

http://www.animenewsnetwork.com/news/2015-01-30/team-aims-to-pierce-moon-with-evangelion-spear-of-longinus/.83876

/sci/, how does this make you feel?

2 posts omitted. Click reply to view.

02/06/15 (Fri) 23:27:58 No.1582

>>1528
Someone is asking how this makes people feel because it obviously is a pretty big fucking deal that someone wants to send something like this to the moon, which is part of space. You fucks don't talk about space here? Funny, I see threads about it.

02/08/15 (Sun) 05:37:22 No.1589

>>1513
>EVA
Oh jesus , its bad enough for the past 20 years that these weebs have been bitching over who was the better waifu , and how the show is so deep. But there actually gonna sperg out further by doing this?

02/08/15 (Sun) 22:18:01 No.1594

>>1589
Its no worse than nuking the moon or sticking flags and capsules on it. That doesn't makee it any less of a waste of money though.

02/09/15 (Mon) 04:47:19 No.1598

The nuke really messed them up.
Eva isn't even that good.

02/09/15 (Mon) 16:29:23 No.1600

>>1582
Space isn't automatically science, and Evangelion sure the fuck isn't either.

File: 1423270930464.jpg (81.29 KB, 600x600, 1:1, 259-zoom.jpg)

02/07/15 (Sat) 01:02:10 No.1583 [Reply]

Hey /sci/, biology major here trying to answer two questions I posed to myself regarding chemistry and chemical reactions. I'm hoping you can help, as both of them aren't you general run-of-the-mill "2+2=4" questions.

1.Let's say I have two buffers : Buffer A, and Buffer B. Assume that the components of each buffer do not react with each other. Assume, also, that I know the pH that each buffer is sitting at. If I mix these two buffers, how can the new pH be calculated? It is not an average of the two. The closest I've come to in my research on this is "it'll be close to the pKa of the stronger buffer".

2. I make hydrogen chloride gas by reaction table salt and sodium bisulfate. I bubble the gas through cold water to make aqueous HCl. There, obviously, is a volume change in the water from the addition of a solute. How can the change in volume in the solvent be calculated, per mole of solute added?

Both of these questions are very hard to deal with, and I've looked up everything I can on each; I spent 5 hours in two different libraries looking for anything I can on the subjects at hand.

So, /sci/, can you point me in the right direction here?

Thanks in advance.

02/07/15 (Sat) 05:29:21 No.1585

>>1583
1. I suspect it will be have like a multi-valent molecule. Say, amino acids at neutral pH will be a mix of (+), (-) and zitterion according to the respective pKa s of the C/N terminus.

For predicting the pH, I think you can write dissociation ratios for either one separately, and get a multivariable equation you can solve.

If you come up with a good, realistic example I can test it empirically.

2. Probably something like (# of HCl molecules)*(Van der Waals volume of each molecule). Water is almost incompressible, adding HCl would be like throwing some apples into a basket full of oranges.

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