### Pendulum length to falling body height ratio? Answered

How long does a pendulum need to be for its time period to be equal to the time it takes for a falling body to drop from a distance equal to the pendulum's length? A general equation as well as a specific solution for Earth surface gravity would be appreciated. With this, I would be able to establish standard time and distance units even if trapped on an island without any instruments other than what I can make from available materials. I'm sure I'm the only one tired that happening so often. Of course, I'd still need a way to establish the gravitatoinal constant if stranded on another planet...

Question by MDude   |  last reply

### Gossamer Falls Copper Works

Any body know how to make a Gossamer Falls Copper Works Will sombody of a How to...?

Topic by kjvman   |  last reply

### Did the today views "resetter" fall asleep at the key board thingee?

Self explanatory, I believe...maybe some body knows the answer?  Maybe there is another place to put this question...I don't know...

Question by Creativeman   |  last reply

### I need a skin-safe body paint that cracks. Any ideas?

I have an idea for a cool makeup effect (for Halloween, movie, etc.) but I can't find out what exactly I need.  I need some kind of body paint that tends to crack (not fall off, just crack), that I can pain on my face and move around to crack it up a bit.  I haven't a clue what kind of paint that would be.  Any ideas?  Thank you for any help!

Question by choward7   |  last reply

### In a simple ir module using ir transmiitter and ir receiver to detect an obstacle , why black bodies are not detected ?

I have observed that black objects are not detected as ir rays are absorbed by the black object also the cicuit does not work when sunlight falls on it?how can i solve this problem?? please help ?

Question by sandiri   |  last reply

### Bee sting thearapy - a natural alternative to classic medication?

Topic by Downunder35m   |  last reply

### goal: robot leaves charging station when battery full, returns when battery falls below threshold. need: battery monitor Answered

Naturally I want a battery-monitoring circuit/electronics that uses as little power as possible. I'd be surprised if such a circuit isn't available off-the-shelf, but I've never seen one advertised as a standalone component I could plug in to add it to my project. Speaking of "my project," it doesn't exist in physical form yet, only in my head, but I'm thinking of an R/C car body, big enough to carry a small video camera or 2; the charging station could be solar panels in a fixed sunny spot that it navigates to, or perhaps (a) panel(s) on board the car (so it could find a sunny spot anywhere during the day, e.g.).

Question by landru   |  last reply

### Best and Favorite Knex Creations

I have been using knex probably for over 10 years and I have built a ton of different weopons and things but a fwew stick out. I do love my new transformers but my best work was a wearable mech suit. The boots could hold over 200 lbs and covered the whole body. My favorite was an AT-AT from starwars where if you hit the underbelly of the walker the head falls off and it drops to the floor like the movie one. I want to know people Best and favorite knex creations over the years.

Topic by glitched9700   |  last reply

### Potatobots Take Paris, New York, China and beyond

Ï»¿Tech meets art as students learn what makes machinery tick, and use those parts to anthropomorphize potatoes.  Not only do they make crazy creatures, they write back-stories for them as well.  "Each year, my students and I take apart old electronics (VCRs, computers, clock radios, and the like). We use the parts like the parts for the old-school Mr. Potato Head kits. In the 50′s, you didn’t get the big plastic potato, you just got face and body parts. We use the gears, springs, screws, wires, and other pieces as the body parts for our Potatobots. We photograph them on blue paper, and then I use GIMP to place them into scenes of the students’ choosing." Find out what happens when a Potatobot falls into a wormhole and how Tim got so much camel:  http://potatobots.wordpress.com/ Did I mention they can shoot lasers from their eyes?  Who knew playing with food could be so much fun?

Topic by scoochmaroo   |  last reply

### A complete roleplaying game in one post

Topic by Kiteman   |  last reply

### USB Flash Drive keyring attachment

Everybody loves their flash drive, and most people keep them on their keys (or if you're really cool, on a lanyard around your neck with some kind of card identifying you as a professional geek). A few months ago I bought a little 4gb Lexar Firefly, and I love it. It's tiny and holds lots of information. As you can see in the picture, the hole where you attach a keyring is in the lid, not on the body of the drive. This cuts down on the drive's size, but means that the drive might fall out of the lid, or get forgotten and left behind. Naturally, this happened after not 3 months of ownership. After a while I lamented ever finding my trusty drive, and tossed the little clear plastic cap. However, lo and behold, I did find my little USB drive a long time later--Bbt now I have no way to attach it to my keys! Does anybody have some ideas for a key-attachment mod for my little firefly? I'd like to avoid adding any kind of bulky casing, but I will if it means not having to drop \$25 on a new one.

Topic by thepeacefish   |  last reply

### K'NEX M249 SAW / FN Minimi

Hey guys! Well, this is my most recent project, the M249 SAW (Squad Automatic Weapon). While the body may look simple enough, I can tell you that this project is no laughing matter. It is sturdy (mostly) and has an amazing pin pull, but is not yet finished. I am not sure weather it will fire a round out of the magazine, and if it did, I am not quite sure if the round wont hit the front sight. It needs a magazine lock (the mag will fall out if you don't hold it in with your hand), the stock connection is not sturdy in any way, and the back sight needs some work. All the same, this is the first accurate looking M249 SAW on 'ibles, and I hope that I can get it "up (my) to standards." Features: Nice looking box magazine Comfortable Sturdy 16 round magazine (ish) Accurate looking (M249 / FN Minimi) Shoots a yellow rod about 20 - 30 ft. Bipod attaches nicely Bipod is strudy Stock looks boss (IMO) Tell me how you think I can improve the gun, I am always open to suggestions. Enjoy! -The Red Book of Westmarch

Topic by The Red Book of Westmarch   |  last reply

### Crazy Dr. Seuss-style House

Check out this NYTimes slideshow of an absolutely awesome house on Long Island!None of the surfaces are level, everything is brightly colored, and you'd have to hang curtains to get any privacy. The architects included poles to help people stay upright when climbing around. I totally want one of these... From the article:The house is off-limits to children, and adults are asked to sign a waiver when they enter. The main concern is the concrete floor, which rises and falls like the surface of a vast, bumpy chocolate chip cookie.But, for Arakawa, 71, an artist who designed the house with his wife, Madeline Gins, the floor is a delight, as well as a proving ground.As he scampered across it with youthful enthusiasm on a Friday evening in March, he compared himself to the first man to walk on the moon. "If Neil Armstrong were here, he would say, "This is even better!Then Ms. Gins, 66, began holding forth about the health benefits of the house, officially called Bioscleave House (Lifespan Extending Villa). Its architecture makes people use their bodies in unexpected ways to maintain equilibrium, and that, she said, will stimulate their immune systems."They ought to build hospitals like this," she said.A reporter, who thinks they should never, ever build hospitals like this, tried to go with the flow.

Topic by canida   |  last reply

### Revised TR8 review

Ok, so I decided to rebuild it, and I found I got some stuff wrongBodyStock: 8/10 Why: comfyHandle: 8/10 Why: Comfy overall, but there is this spot where I get poked sometimesTrigger: 9/10 Why: seems very reliable, It didnt break this time around (idk why, I built it the exact same way I did from last time), but when you remove the rubberbands, that green rod can fall out.Barrel: 9/10 Why: works very well, but its a generic tube and stickTurret: 10/10 Why: It works awesome with the rest of the gun. Looks: 9/10 Why: looks tight, especially when loaded up with red rods, but the turret seems a bit out of place with the rest of the gunPerformanceRange: 10/10 Why: 90-100 feet flat (2 rubberbands)Power: 10/10 Why: its the most powerful gun I have ever made. It can shoot through various heavy duty cardboard boxes with 2 rubberbandsReliability: 8/10 Why: the turret is a very effective method for the repeater, however, it sometimes skips rounds, but rarely.Innovation: 7/10 Why: nothing that new, except for the revolving mech and the trigger.Recommendation: Yes, I would recommend it to anyone who doesnt want to use a bulky knexsayer, or a single shot in a knex war.Final rating: 9/10

### How can I make a giant bike cog like this one? Answered

Here's a site with  the inspiring article: http://www.cnet.com/news/fast-fixie-bicycle-with-giant-chainring-aims-for-100-mph/  Anyways, I want one. First of all I would suppose I'd need a pattern. What program would you suggest I used to make a pattern?  A solid circle of metal with teeth on it will do. I'm thinking of gluing a pattern to a piece of metal, cutting it out as best I can with a grinder then going bike to clean it up with a tungsten carbdide dremel bit. I gues it could be a few thinner sheets of metal that could be  spot welded together. I dont have any tech shops/idea foundries in my town. I say that because I'm wondering could I just create some type of file that a mill machine could read and cut it out for me? I have a couple different reasons for wanting a larger cog, the practical one being I want a cog large enough that the pedals would be moving around very slowly so you could just shift your weiht back and forth, more falling with your body weight than pedaling. The 2nd reason, more lofty and long term goalish is if you can get this much power from a bike, to propel it 100 mph, it just seems reasonable that a human powered aircraft is within reach, as in attatch a hang glider to a bike and have the pedaling able power a propeller once airborne. Anyways, how would you go about making a giant cog?

### How could I tell if someone installed a phone tap, camera, or voice recorder in my room?

When I leave for work, I sometimes leave my bedroom window open. There is a medium sized gap between the screen about the size of your fist. Is there a way I could tell if someone has tapped my house? Recently my Samsung Flat-Screen has been very snowy and I remember that you could tell is something has been tapped because they interfere with your tv. The house I just moved into also has a wire panel outside my window which you can reach. My room is first floor, please help. I cannot sleep. I also read that you can tell just if you can pick up RF signals coming from the device. Can someone give me a schematic for an RF Signal detector? I can't afford the commercial ones, I once read a stat that if you suddenly wake around 2am or 3am there is %80 chance of someone staring at you. Your body naturally senses this somehow. Well, when I looked at my window, I saw a light then after a few seconds it was gone. I went outside and I heard a couple of cans fall over and my fence my shaking like it was moved. My gate is usually locked but it is a reletively short fence. I haven't slept for days. I can't stand it. I'm going today to buy some black curtains as these cheap plastic blinds aren't cutting it

Question by halo99   |  last reply

### Convert a basic plastic toy car to autonomous, request for comments. Answered

Here is my idea: Convert a basic plastic toy car to autonomous. Using an arduino or similar, convert a basic toy car to autonomous. My son has a toy car approximately 10 inches or so in length he outgrew.  It is quite rugged and would be a shame to throw it away as it is in very good condition. The wheels are approximately 4 inches high.  I have opened the chassis and there is a gap of approximately 4 centimetres (rising to 7 centimetres at the front and back) between the base and the body. There is more than enough room to fit an arduino in there along with a couple of motors and batteries (although realistically I would fit the batteries externally so they can be replaced easily). The wheels are on metal rods approximately 3 millimetres thick that travel the width of the car. []-----[] If I was to cut each bar in the centre I would end up with the 4 wheels on a length of metal rod. Using a self-locking washer on the inside of the chassis I could prevent the wheels falling out: []-)--- If I connected a motor to the back wheels and linked the front and back wheels so the back wheels drove the front wheels I should get a tank-track like system - turning the back left wheel would turn the front left wheel, same for the right hand side. Controlling the motors would allow forward, reverse, left, right and turning on the spot mobility. Using sensors to detect distance, light, darkness, collisions etc which on an arduino would be trivial would give a truly autonomous vehicle. Am I way off track here or is my idea feasible? Please, comment away.. I will give it a go anyway but before I start I wish to know that it can in theory work :)

Question by gregoryfenton   |  last reply

### Halloween Makeup

Topic by fungus amungus   |  last reply

### Wood gasifiers and safety - Carbon Monoxide poisoning - hospital

Topic by AtomRat   |  last reply

### Bolt Action Rotary Magazine Gun (updated with internals)

Alright, it's been a while, forgive me. I work in spurts of an hour or two every few nights. It's not quite finished, but it's at a point I'm comfortable showing. I'm also working with BM, so hopefully he can make some improvements on it before it's posted. This gun is the combination of two different goals I've had. First off, I always wanted to make a bolt action. I came up with the idea for the modern bolt action long ago but was beaten to the punch. So since then, as others have made their own bolt actions, I still struggled to make one up to my own standards. I wanted something sleek and compact with a removable magazine. Second, I went off on a little tangent while building, which then turned into its own project: a rotary magazine. While it's been done before, I don't know if it was ever successfully used in a gun. It's more about the novelty than the practicality, but what it does do is give you more storage in a compact design and act as a decent foregrip. I wanted to make it a decently usable. At first I thought of making just some cruddy gun to show off the concept as a usable magazine, but then I decided I may as well go the full nine yards and make it perform well. So this is what I ended up with. I don't have a real name for it yet, but I've considered calling it the Barackuda, a portmanteau of Barack (Obama) and barracuda because...well why not. I wanted to keep it as compact as possible, so I used a barrel similar to my Oodassault 3 series and a stock connection similar to my PDR. The stock is a bit long compared to the body of the gun, so it may look awkward, but I wanted to give at least enough room to aim the gun without sticking the pin into your eye. The blue connectors in the stock stop the bolt right after the trigger engages. The bolt is somewhat typical. I like how it sits flush with the back of the gun rather than looking like an extension on the back of it. The handle isn't amazing, just a variation of my tried and true handle I've come to like. The trigger also isn't amazing, and in hindsight, I want to block a bit further back still, but it works for the limited space I've got. The magazine on the other hand is magical. Go look at my last topic for details on its operation. This version is for yellow rods. I've added a rotary lock and band. When the middle rod is pushed toward the trigger (like in the pic), it's locked. It can securely contain 10 usable yellow rods while locked, though it can load up to 12, the top 2 can fall out. You insert it into the gun by pressing the top two red rods at an angle into gaps in the grey connectors at the front, then rotate the magazine, slightly pushing in, until you get the white rod in the gaps of the yellow connector. Finally, you push in the middle red rod by the trigger all the way forward to unlock the magazine. Edit (9/10/2015): Made my adjustments and now I'm mostly satisfied with the weapon. Here's the video.

Topic by TheDunkis   |  last reply

### Funny Labels

Topic by LoneWolf   |  last reply

### Is my book good ?

Topic by albylovesscience   |  last reply

### Detecting Very Slight Tendon Movements In Wrist

I've always had an intense fascination for lucid dreaming. Finding ways to communicate or control outside devices based off the slight body movements that are possible despite the natural paralysis during sleep is a topic of great interest to me. I have several LDs (lucid dreams) each night and through much experimentation have found that with a bit of concentration, I could move my fingers enough to trigger very sensitive buttons (if placed perfectly before falling asleep) or to grip myself (if my hand is placed say, near my neck before intentionally entering a dream from waking) such that the sensation of my fingers reaching my neck would wake me. These experiments were proof enough that if I perhaps had some sort of glove or wrist mounted piezo sensors that are able to detect the individual tendon/finger movements with high enough sensitivity, combined with software that can parse patterns and reliably filter out minor unintentional simultaneous movements for the fingers that are prone to movement when others nearby are moved, it would be possible to establish one way communication with outside devices, the Internet, etc. Input could be in the form of different patterns or even text (tap code, morse code, or through a hybrid allowing use of each digit of the hands) or musical notes (each finger representing a note of a scale with a finger or two used to change octave or to toggle sustain.) As a musician who "writes" his best music within his dreams, this could be quite handy for getting melodies down before they vanish from memory on waking. For example, to activate input, you could perform a simple pattern that is unlikely to be triggered unintentionally. It could be as easy as left thumb flex, right thumb flex repeated in that order several times. From this point, you could use another pattern to choose to trigger an alarm (sound, vibration or electrical shock), or to initiate musical or text recording. There are many different uses that could be explored, and it might even be possible that 2 way communication could be established if a reliable method of transmitting to the dreamer without waking them could be created. This is however beyond the scope of my intentions. I have suffered from sleep paralysis on a nightly basis for over a decade now which can be extremely frightening and last up to several minutes, and during this time I am able to move my fingers as well as shake my head back and forth (which I need to do to break out otherwise the paralysis will persist until I'm pulled into a nightmare.) My solution to these terrifying experiences was wearing a heart rate monitor with an alarm that goes off past a certain BPM, which only happens when I am frightened. Now that I am so used to these experiences, my heart rate does not increase enough that I can reliably use it as a trigger without also waking myself out of exciting dreams that I'd rather not have prematurely terminated. I am fairly confident that a device such as this could help with breaking out of my paralysis at will and PERHAPS even be sold commercially to other sufferers of this condition, however niche the market. Giving me control over my sleep paralysis alone would be a highly satisfactory result with significant quality of life improvements and be worth the effort of building this. Waking up partners in bed with my head thrashing is less than ideal! As an avid software programmer, I do not think that the code involved would be terribly difficult. However, I have very little electrical knowledge and building this without existing plans would be tough and time consuming. It would be enough to have a pressure/flex voltage for each digit transmitted to a Raspberry Pi or via Bluetooth to a computer and the rest could be done through software. My questions are.. Does a commercial device exist that would be suitable for my purposes and not be terribly expensive? Perhaps a glove? Is a wrist strap with piezo sensors over each tendon that control the fingers a realistic possibility to achieve my goals? I do not need to know the position of the fingers or whether it is pushing against something. Just that movement is being attempted. Do existing plans exist to create a similar device? Thank you!

Question by Ril900   |  last reply

### Declaration of Independence

When in the Course of human events it becomes necessary for one people to dissolve the creative bands which have connected them with another and to assume among the powers of the earth, the separate and equal station to which the Laws of Nature and of Nature's God entitle them, a decent respect to the opinions of mankind requires that they should declare the causes which impel them to the separation.We hold these truths to be self-evident, that all makers are created equal, that they are endowed by their Creator with certain unalienable Rights, that among these are Tools, Warranty and the pursuit of Customness. - That to secure these rights, Websites are instituted among Makers, deriving their just powers from the consent of the members, -That whenever any Form of Website becomes destructive of these ends, it is the Right of the People to alter or to abolish it, and to institute new Webspace, laying its foundation on such principles and organizing its powers in such form, as to them shall seem most likely to effect their Ideas and Projects. Prudence, indeed, will dictate that Websites long established should not be changed for light and transient causes; and accordingly all experience hath shewn that mankind are more disposed to suffer, while evils are sufferable than to right themselves by abolishing the forms to which they are accustomed. But when a long train of abuses and usurpations, pursuing invariably the same Object evinces a design to reduce them under absolute Despotism, it is their right, it is their duty, to throw off such Webmasters, and to provide new Guards for their future security. - Such has been the patient sufferance of these Users; and such is now the necessity which constrains them to alter their former Systems of Website. The history of the present CEO of Instructables is a history of repeated injuries and usurpations, all having in direct object the establishment of an absolute Tyranny over these Members. To prove this, let Facts be submitted to a candid world.He has refused his Assent to Features, the most wholesome and necessary for the public good.He has forbidden his Staff to pass Forum Topics of immediate and pressing importance, unless suspended in their operation till his Assent should be obtained; and when so suspended, he has utterly neglected to attend to them.He has refused to pass other Laws for the accommodation of large districts of people, unless those people would relinquish the right of Representation in the Legislature, a right inestimable to them and formidable to tyrants only.He has called together legislative bodies at places unusual, uncomfortable, and distant from the depository of their Public Records, for the sole purpose of fatiguing them into compliance with his measures.He has dissolved Comments and Topics repeatedly, for opposing with (wo)manly firmness his invasions on the rights of the people.He has refused for a long time, after such dissolutions, to cause others to be elected, whereby the Legislative Powers, incapable of Annihilation, have returned to the People at large for their exercise; the State remaining in the mean time exposed to all the dangers of invasion from without, and convulsions within.He has endeavoured to prevent the population of these Users; for that purpose obstructing the Laws for Naturalization of Free accounts; refusing to pass others to encourage their migrations hither, and raising the conditions of new Appropriations of Features.He has obstructed the Administration of Justice by refusing his Assent to TOS for establishing Moderating Powers.He has made Sherrifans dependent on his Will alone for the tenure of their offices, and the amount and payment of their salaries.He has erected a multitude of New Offices, and sent hither swarms of Officers to harass our people and eat out their substance.He has kept among us, in times of peace, Standing Filters without the Consent of our legislatures.He has affected to render the Military independent of and superior to the Civil Power.He has combined with others to subject us to a jurisdiction foreign to our constitution, and unacknowledged by our TOS; giving his Assent to their Acts of pretended Legislation:For quartering large bodies of armed troops among us:For protecting them, by a mock Trial from punishment for any Murders which they should commit on the Inhabitants of these States:For cutting off our Allsteps with all parts of the world:For imposing Pro fees on us without our Consent:For depriving us in many cases, of the benefit of Refund of Fees:For transporting us beyond Seas to be tried for pretended offences:For abolishing the free System of Exchange of Ideas in a neighbouring Webspace, establishing therein an Arbitrary government, and enlarging its Boundaries so as to render it at once an example and fit instrument for introducing the same absolute rule into these directories:For taking away our Favorites, abolishing our most valuable Features and altering fundamentally the Forms of our Websites:For suspending our own Legislatures, and declaring themselves invested with power to legislate for us in all cases whatsoever.He has abdicated Government here, by declaring us out of his Protection and waging War against us.He has plundered our seas, ravaged our coasts, burnt our towns, and destroyed the lives of our people.He is at this time transporting large Armies of foreign Mercenaries to compleat the works of death, desolation, and tyranny, already begun with circumstances of Cruelty & Perfidy scarcely paralleled in the most barbarous ages, and totally unworthy the Head of a civilized website.He has constrained our fellow Citizens taken Captive on the high Seas to bear Arms against their Country, to become the executioners of their friends and Brethren, or to fall themselves by their Hands.He has excited domestic insurrections amongst us, and has endeavoured to bring on the inhabitants of our frontiers, the merciless Indian Spammers whose known rule of warfare, is an undistinguished destruction of all OSs, platforms and softwares.In every stage of these Oppressions We have Petitioned for Redress in the most humble terms: Our repeated Petitions have been answered only by repeated injury. A Prince, whose character is thus marked by every act which may define a Tyrant, is unfit to be El Jefe of a free people.Nor have We been wanting in attentions to our Hacking brethren. We have warned them from time to time of attempts by their staff to extend an unwarrantable jurisdiction over us. We have reminded them of the circumstances of our emigration and settlement here. We have appealed to their native justice and magnanimity, and we have conjured them by the ties of our common kindred to disavow these usurpations, which would inevitably interrupt our connections and correspondence. They too have been deaf to the voice of justice and of consanguinity. We must, therefore, acquiesce in the necessity, which denounces our Separation, and hold them, as we hold the rest of mankind, Enemies in War, in Peace Friends.We, therefore, the Representatives of the Members of Instructables, in Freenode on #instructables, Assembled, appealing to the Supreme Judge of the world for the rectitude of our intentions, do, in the Name, and by Authority of the good Posters of these Forums, solemnly publish and declare, That these united Dirs are, and of Right ought to be Free and Independent Sites, that they are Absolved from all Allegiance to the Robot Crown, and that all TCP/IP connection between them and the Site of Instructables, is and ought to be totally dissolved; and that as Free and Independent Sites, they have full Power to assign Mods, post content, contract sponsors, establish Advertising, and to do all other Acts and Things which Independent Sites may of right do. - And for the support of this Declaration, with a firm reliance on the protection of Divine Providence, we mutually pledge to each other our Tools, our Kiteboards, and our sacred Honor.None of the above, is, of course, intended seriously. Dur. IT'S A JOKE, peoplez. Sheesh.

Topic by Lithium Rain   |  last reply

### The Dream Factory - Squid Labs and Instructables in Wired September 2005

Topic by ewilhelm

### How to ride DH safely

Topic by struckbyanarrow

### a Blucky corpse

Topic by susanfromhauntspace   |  last reply

### Can you check this design? Answered

Question by rimar2000   |  last reply