Search for length in Topics


length affect velocity

Depending of length of a barrel can it change the velocity

Topic by Cheyannelovesham    |  last reply


Projector length of tube? Answered

I was curious if it's possibly to extend a projected image, from a projector (like tv/computer) down about a foot of tube. Tube would be 1 - 2 inches wide. If this isn't possibly what would be the smallest width the tube would have to be for it able to go down a foot of length?

Question by ebodenberg    |  last reply


new length of mastic tape? Answered

 Hi all.. Could you help me to know :  if I stretch a roll of mastic tape is  1/4'' thick x 1.5 '' wide x 360' long  to form 1/8'' Thick x 1'' wide I will have how much of  new length ??? Thank you so much in advance for your time.

Question by lam    |  last reply


Layers V.S. Length; Electromagnets ? Answered

Ok, so I am going to be working on a project that involves electromagnets and the on thing I have never gotten straight is this: To make the most effective magnetic field possible do I make the (hypothetically) 100' of wire a long coil with only a couple of layers or 100' of wire a short coil with many layers? I have always come across conflicting views on if length improve the fields or weaken them. Any insight would be helpful and if you could also provide a good reference site for these types of questions that would also be appreciated. 

Question by Jayccob    |  last reply


Max length for running leds over cat5e? Answered

If i run 2 leds over cat5e cable how far away from the Arduino can I get? Thanks, Kade

Question by FarmerKJS    |  last reply


Where can I find convex lenses with a focal length of Answered

Hello, I'm searching for a convex lens for focussing the beam of my laser. The focal length should be smaller than 1cm. I've searched in cd/dvd readers/burners but those lenses are never good enough because either the focal length or the size of the lens isn't good. Thanks in advance, Electorials

Question by DELETED_Electorials    |  last reply


Amount of video sections and duration you can use in a single INstructable?

I intend to upload my step-by-step video guide to making a Nintendo N64 console system into a handheld portable device; am currently about 60% completed in the project and uploaded about 10 videos to YouTube to cover the project up to this point.  By the time the project finishes, I could be needing about 20-25 videos, up to 10 mins long each. My intention is to upload the videos to this site for others to see; so my question is this - would I be able to post this volume of videos to this site on one topic; or would I need to put all the videos together? I have only just joined Instructables so a noob here, so would appreciate your comments and advice.  To give an idea of the videos I have for the N64 project so far,   http://moddedbybacteria.wordpress.com/retro-console-system-modding-guides/nintendo-n64-video-guide-log/ Better I ask at this stage! Obviously I intend to upload many other videos in the future, however this biggie might be the first one I upload here.

Topic by MODDEDbyBACTERIA    |  last reply


What program can I use to determine unknown lengths in a photo? Answered

I am trying to find the exact dimensions of an object in a photo, I know its length, but I was wondering if there is maybe a program where I could input that one value, then like drag a line or something to determine the other lengths based off that one, I am looking to avoid any tedious math, thanks!

Question by thebluemartyr    |  last reply


Measuring device wich read the dimensions of an object in 1 time?

I want catalog my collection of inkwells, including the dimensions of each object (length, width, height, diameter). The largest size is 50 cm. I wonder if there is a device that measures all the dimensions in one time, whether or not electronically. If not, do you have suggestions so I can make it myself? All ideas are welcome.

Question by Frederiko    |  last reply


How do you determine the length of an antenna and the size of a fractal antenna? Answered

In an instructable, the formula for calculating antenna length was given as "length in meters =300 / frequency in MHz".  The example given was for a Bluetooth antenna with a frequency of 2450MHz.  The antenna length was calculated as 300/2450 = 0.1225m = 12cm.  The author then divided it by 4 to make a "quarter wave" antenna length of 30mm.  Why divide it by 4 and what is the benefit of a "quarter wave" antenna.  What is the effect of the conductor leading to the antenna?  If the 30mm antenna is soldered to a 4mm lead, does that result in a 34mm antenna?  For a fractal antenna, should the 30mm length of wire be folded into a fractal shape or should the total fractal antenna be 30mm in width?  I have read somewhere that one of the benefits of a fractal antenna is that they are able to receive signals of different wave lengths.

Question by fcampbell    |  last reply


Antenna length for a frequency modulated signal.

I  am given to understand that the length of an antenna is proportional to the wavelength of the signal that is fed to it (a quarter wavelength, for example). In the case of a signal modulated by amplitude, the frequency (and therefore wavelength) of the carrier wave remains unchanged. However, in the case of a signal modulated by frequency, the signal fed to the antenna will vary in frequency (and, therefore, wavelength). My query is this : how would one go about calculating the length of an antenna for a frequency modulated signal? Its frequency is not constant, so to construct an antenna of say, a quarter of the wavelength, would be impossible. I thank you in advance for your assistance. AlexHalford

Question by alexhalford    |  last reply


A thing about usb cable lengths!

 Well apparently according to many websites I've visted, claim that the longest cable you can use for a usb device is just a little over 15 feet. That said, I'm one for completely disregarding warnings. According to the text on one website: Q: How long of a cable can I use to connect my USB device? A: In practice, the USB specification limits the cable length between Full-speed USB devices to 5 meters (A little under 16 feet, 5 inches). For a Low-Speed device, the limit is 3 meters (9 feet, 10 inches). So my dilemma is that I have an a$$hole neighbour that is stealing things from me and I want to catch him. Being cheap, I'm going to use my webcam instead of spending $50 on a low resolution color camera that only outputs composite (although that would allow me to make cables easier and I DO have a capture card on my pc) but this is besides the point. So I found a telephone cable (as it has 4 wires just like USB) and I figure it's got to be AT LEAST 20 feet long, maybe 30, which is long enough for what I need. I thought because It's all over the internet how apparently the limit is 15 feet, that is would just NOT work at all. 10 minutes later I had spliced the telephone wire between the USB connector and the webcam, wiring black to black, red to red, green to green, and yellow to white (usb side). Upon plugging it into my desktop usb hub, sure enough, my computer recognized it, and the video came through just fine. So I post this forum-topic to SHOW that it is infact possible to go OVER the so-called usb limit. I got the idea originally from a video I watched last night where a guy had a webcam mounted to the middle of his ceiling for a project he was working on, and it appeared that he had spliced in a longer wire than the webcam came with, and strung it across the ceiling, and then the wall. I DO have a question and I AGAIN request the help of all you helpful instructables members! My webcam as-is can see IR (infared) light, as I've tested this with a remote control and it can see the white light coming out of it. So the question is, how hard would it be to build an array of IR LED's to light up my yard, not even nessesarily pointing away from the source of the webcam, but say, an array of led's above the door of my shed shining down so if someone does attempt to enter my shed, I will be able to clearly record them. Long post I know, but this is VERY important to me that this works and I'm hoping I didn't waste my time constructing this, I've had a few things stolen from me recently and it's really pissing me off. For instance, one of my bicycles was stolen, RIGHT FROM MY FRONT DOORSTEP! It has wayyyy more sentimental value to me than actual cash value and I'm literally ready to choke the living sh)t out of someone!

Topic by Punkguyta    |  last reply



What are the dimensions of pallet wood? Answered

Yes, I've searched. Also, I don't mean what are the dimensions of the pallets in general, I mean the wooden planks they're made of. PS: I realize it may vary. Estimates are OK. I'm mainly worried about thickness. Thanks for any help.

Question by travw    |  last reply


Printer hack needed

 Would anyone know how I might hack my HP Photosmart C7280 to print unlimited (or at least 72") page lengths?  I’m trying to print a banner from Illustrator, and the printer stops at 11".  Width limit is a given, but there’s no reason I see that a printer couldn’t just keep on printing length-wise. Any suggestions? Thanks, Kennan

Topic by kennan    |  last reply


What is the size for an avatar picture without if leaving any left over space?

I looking for a new avatar, and I want to know the length and width without leaving a white border.

Question by Rock Soldier    |  last reply


Why do capacitors increase arc lengths?

I have seen a lot of videos with people increasing the arc length of a nst or mot with capacitors and i was wondering why this works. Also, is the capacitor increasing the voltage (higher potential difference, so longer arcs) or the amps (more ionisation so you can draw the arc longe)r?

Question by makincoolstuff    |  last reply


Are K'NEX Hinges and Ball'n'Socket joints the same length? Answered

Well, that's my question. I would like to know because I see people make mag's with he hinges on the out side and the ball'n'socket joints on the inside of the sides of the mag, and It is useful info anyhow. Look a the pic...if they are the same length, how did Senior Waffleman make that mag?

Question by The Red Book of Westmarch    |  last reply


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


Hang a curtain the length of a room, what's the cheapest way? Answered

I live in a house with no closets and bought one of those wire closet racks and ran it across the back of my bedroom. It works but leaves a messy appearance with no doors and I have a wood stove and a dusty farmhouse. I have material for curtains but can't afford a rod of that strength and length. So...whatcha got?

Question by tbcross    |  last reply


Electronics: increase trigger signal length for USB gamepad

This is related to my last Instructable. https://www.instructables.com/id/cheap-USB-slotcar-timer-interface/ Sometimes when I install the track piece I am using on a fast straight I am missing laps. The problem could be USB polling rates in Windows 8. I found no way to increase polling rates to 500 or 1000Hz instead of the aprox. 180Hz. First I don't know if the car triggers at all when I go over the contact very fast or if the USB polling is the problem. i can try to wire a LED in and see if it is flashing up when the counter is not working. My thought is that I could increase the signal length when the car triggers the button. Any ideas how this could be done? My second problem is related. I also got a IR-gap-sensor. I understand that I need some kind of relais to make it trigger my USB gamepad buttons? Please help an electronically uneducated guy! I have the feeling that the answers to my questions are probably not that hard anyways.

Topic by heavyweather    |  last reply


Few questions about coil physics and capacitors.

Hello.  Hopefully there's some smart electromechanical and physics guys on this board. Long story short I have been working on a coil gun project for about a month now. Originally I was using disposable flash camera circuit, a simple push button, and a coil I took out of a fan. The coil itself is roughly 42 gauge wire, wound an inch long with about 14-18 layers. I achieved best results from this coil, about 4% efficiency, using a 200v 470uf capacitor and a magnetic projectile. However when I used a more powerful capacitor rated at 400v 820uf efficiencies were much lower. I realized the coil was limited and the capacitors energy wasn't being maximized. So I bought some 16 gauge magnet wire to wind a new coil. I wound a coil 40mm long, 3 layers thick around a 1 cm pvc pipe. The coil works but once again there is a huge loss of efficiency at higher energies.  So I need to wind a new coil.  Now here are my questions. 1.  I have read that a coil should be about 33% longer than the projectile.  Is this accurate? 2a.  Is there a magical equation to determine the number of layers a coil should have if all other factors are known? 2b.  How many layers of 16 gauge wire should I use for a coil wrapped around a 1/4 inch barrel to maximize efficiency with a 400v 820uf capacitor?  What about a 200v 1200uf capacitor? 3.  Could someone please demonstrate how to convert farads into amps? My main objective is an optically triggered multi stage coil gun with kinetic energy transfer of above 30 joules. I've moved away from flash camera circuitry and am now using dc to dc converters to charge the capacitors.  I need to find out how to convert farads into amps to figure out what kind of transistors I need for the trigger switch.  Any help is truly appreciated.

Topic by MurdaMastaMike  



What is the allowable size in pixels (Length X Height) for a profile picture?

Also, how do you completely REMOVE your profile picture?

Question by ssj152    |  last reply


Is there a way to estimate how long an antenna is?

If I built a radio transmitter and then attached it to an antenna of unknown length, is there a way to calculate the length of it using transmissions? Or, as a separate question, if I had an antenna of known length and then increased or decreased the length, would there be a way to estimate the new length from transmission properties (basically without physically measuring the antenna? Assume the antenna is a straight line.

Question by kakashibatosi    |  last reply



Does anyone have an estimate of the length of clothesline needed to dry a kilogram of clothes?

I am proposing to a large organization that they change from using dryers to using clotheslines. They dry approximately 60 kilograms of clothes per day. How much space would they need to replace this with clothesline drying? It is typical clothes of the people who live there at the site which is located in a warm country.

Question by rlimanek    |  last reply


How could I calculate the best lengths for a barrel of an air powered shotgun?

Hey there community, i have asked a couple questions here before and i appreciate your answers so very much. this is why i have come to you today again to ask anotger. first off, sorry fir my grammar and spelling errors  im on my phone. now on to my question... i am building an air powered shotgun because i love bb guns and pellet rifles. however, there is no pellet shotgun really out there on the market that is of good quality. so, i want to make my own. . i am following kip kays law rocjet paintball launcher design, but i want to put a barrel that has many .180 in. diameter tubes within it to contain the BBs. the thing that is going to powere it is a  12g co2 canister that is hooked into a paintball quick change cylinder. I know tyat i must do math in order to get the right chamber to barrel ratio. i want the enrrgy within the canister ti be put to use as efficiently as possible, that is so that i am not wasting energy and that i have enough energy. so, any help would be appreciated. thanks again

Question by XBLmonster    |  last reply


Does the length of a fluorescent tube matter? Will a shorter fluorescent tube work in a longer fixture?

Assuming the wattage is the same. I have some 15" fluorescent tubes. Will they work in fixtures made for longer tubes if the wattage is the same?

Question by conrad141    |  last reply


ISO 4in diam clear tube 3-4ft in length for sm pet slide

Hello, I was watching a video where someone was using a mailing tube a hedgehog slide. I wanted to do the same with our heggie as he loves to burrow and will dive off any ledge he can find if we don't watch him. I think the one she used was 3in, but our heggie needs a 4in round and since here is a bit rounder; it needs to be about 3-4ft as well, though we could cut it down. I would like to find an alternative that is clear or semi-clear as it would be nice to be able to see him in the tube as he slides. It also needs to be fairly inexpensive. For anyone interested, our heggies name happens to be Burrow as well. Maybe a fairy whispered it my ear because we choose the name when he was no larger than a large spiky button and it was 6 weeks before we could bring him home. He has wobbly hedgehog syndrome and we really want him to have some fun.  Thanks for any help, Liocorno

Topic by liocorno    |  last reply


Bluetooth boost question?

I want to boost my bluetooth dongle. On some Instructables there are mentions of getting an exactly correct length.  On others the length and shape seem to be arbitrary.  If I want to add more antenna to my bluetooth dongle, do I have to make it an exact length or shape?

Question by finfan7    |  last reply


How much big in length and size blades and what rpm of motor do I need to lift 600 kg of weight like helicopter?

How determine what size blades ( length , width ) and what rpm do the helicopter need to lift a specific weight like 600

Question by MuhammadK19    |  last reply


Can someone help me identify this bayonet?

Have this bayonet, i know its around the WW-II era, i believe german, but cant get a correct description Overall length 15.4" Blade length 10.15" Handle length 5.25" handle feels kinda plastic, any info will help

Question by mike140065    |  last reply


Does anybody play bagpipes?

If anyone plays the Great Highland Bagpipes, i was wondering if you could possibly measure your drone reeds and post the measurements, because I've been searching and searching and cannot figure out the lengths or diameters of the bass and tenor drone reeds. So, Bass Reed length Tenor Reed Length And the length of the tongues on each of those as well. If anybody could do that i would be really thankful! Thanks! Luc

Question by FunkNattidelic    |  last reply


How can I Make a Length Extention For a Fire Extinguiser?Like A Really Long One?

Like A Really Long One? List Materials and Stores I Can Go To? Also How Much it Costs?

Question by jattstar11    |  last reply


Long bow sizing questions? Answered

I was wondering what the actual length of a long bow with a string length of 48inch amo would be I basically want to know what the length of the bow itself with the string on would be??  Also wondering if a 30 pound draw or 20 pound draw would be better for a small person small game hunting?? Thanks!! 

Question by camping crazy    |  last reply


rubber bands; Stretchy not stretchy? Answered

Assuming we are using the same amount of both, is it better to use small rubber bands that stretch to there fullest on the length of the gun or thick rubber bands that stretch over the full length of the gun?

Question by Wafflicious    |  last reply


how much weight?

The length of the bed frame is75" and width is 53" the hinges are long the length edge. the drawing shows the dark lines of how the rope is set up. the mattress is a full size 8" coil spring futon (60lbs) 1.5 sheets of plywood at 1/2"x75"x60" looking to find what i need for counter weight and the math to get the answer. thank you for your time.

Question by labanW    |  last reply


Any suggestions for a 5mm - 10mm telescope eyepiece?

I am currently using a home built 3'' refracting telescope, and want to build a shorter focal length eyepiece to get some detail for observing planets (lunar surface, rings on Saturn, more of the moons of Jupiter. The current setup uses a plossl eyepiece with about a 25mm focal length, giving 30 to 40x magnification, and allowing very clear viewing of the moon, and will pick out three of Jupiters moons on a clear night. Ideally I'd like a 5mm to 10mm focal length, for a 100 to 200x magnification. I've considered using the lens out of a DVD drive, which looks as though it could work, although I've only seen one example of it done before. I also have a selection of reasonable quality prisms and lenses about 1'' diameter, with focal lengths from about 2'' to 4''. So, how well would a DVD drive lens work, and are there any interesting designs that make an eyepiece with a focal length significantly shorter than any of its component lenses (in the same way the focal length of a plossl is about 1/2 the focal length of the lenses used). Thanks in advance for any help. (Would this get better response in the photography section)

Topic by The Skinnerz    |  last reply


wifi usb key receiver+strainer+length of cable+wifi router=my apartment has wifi?

Will it work (with/without a usb-ethernet adapter) or at all?

Question by sacredbean    |  last reply


RFID antenna question. Answered

How sensitive is RFID functionality to the length of its antenna? Specifically, if I had an RFID like this one, cut the antenna and then resoldered it, would the loss in antenna length (I'm guessing about half an inch) affect the workings of the device?

Question by Kiteman    |  last reply


Can anyone identify this bayonet? Answered

I have a (probably) WWII-era bayonet that I would like identified. The dimensions are as follows: Overall length: 17.75" Blade length: 11.50" Handle length: 5.25" Blade width:.875" Blade thickness:.25" Handle: Wood scales epoxied to skeletonized metal tang Sheath: Olive green paint on metal I would like to know the type (i.e. m1942), era, and any other relevant info.  

Question by black hole    |  last reply


Quilting Is there a way to piece the backing panels for a large quilt matching printed fabric?

I understand the concept of repeats in printed fabric. I get confused using such large pieces for fabric. I am working with 3 lengths of batik for a queen sized backing, each length is 100 inches.

Question    |  last reply


What's the name of this brass part?

This is on an adjustable length cane, where this thing can be pushed into the inside of the tube to adjust length of the cane, and pushed out by a spring with a "click" sound to lock the length. This is also on kayak paddles to select and lock the angle of the paddles. In fact, this is fairly common and used in many other places... But I don't know its name. I want to use this on one of my project and I am not sure what name should I use to search for the parts. Anyone can help? Thanks!

Topic by ccyg8774    |  last reply


Can I use cat5 wire to extend the length of solar cells/battery packs for my deck lights?

I have four sets of solar deck lights on back porch but can't get good sun. The solar cell/ battery pack has 3 rechargeable 1.5 AA batteries and I'm pretty sure it connects to the light string with 24 or 22 gauge braided wire. Can I use cat5 22 gauge solid copper to extend the panels about 75 feet for full sun? I have tons of cat5 and cat3 wire available as well as gel insulated 3m scotchlocks to splice the wires. And if possible, can I run all four cells off 1 cat5 run (noting the cat5 has 4 pair wiring, a pair for each light string).

Question by Punmunkey    |  last reply


I'd like to make a homemade log marker for chainsawing firewood.? Answered

There are products on the market that are basically a wheel attached to a spray paint can.  As you roll he wheel over a log, it marks the log every X inches.  You need to buy different wheels for different marking lengths. Basically, the plan is to have a log marked every X inches so we know where to cut it for perfect firewood length logs.  Alternate tools available are measuring sticks that attach to your saw, but they are awkward and limit your saw to only making firewood (you can't use it to cut down or limb up the trees with the attachment). I normally use the saw length (on my 18" saw), or the body length (on my 32" saw) for a guide, but a spraypaint thingy would be much simpler.

Question by jparr1    |  last reply


Stirling engine displacer design? Answered

I am designing a gamma Stirling engine (this type) and I am unsure how long the piston should be and how long its stroke length should be the specs for the cylinder and piston pipes are below. The pipe for the cylinder is stainless steel. Wall thickness: 1.56mm Outer diameter: 31.7mm Inner diameter: 28.6 Length: 200mm (can be cut smaller) (Stainless steel cap will be welded to one end, the other end where the shaft comes out will be plugged with this nylon/graphite stuff) The pipe for the displacer piston is aluminium pipe.  Wall thickness: 1mm Outer diameter: 27.88mm Inner diameter: 25.88mm Length: ? (Two aluminium plugs will be used to seal its ends) How long should the piston, cylinder and stroke lengths be based on the specs?

Question by The MadScientist    |  last reply


Framing longer walls for garage/shed.

Most DIY sites give instructions using 8ft or common lengths available from any local supplier illustrating walls using standard lengths. I want to make a garage 16ft x 22ft and do not know how to span across the 22ft section to make a full length wall using more than one board. One to two windows per wall and one exterior door with a gambrel roof, I thought this would be relatively easy but apparently not for a novice carpenter. I just finished pouring my own concrete slab thinking the internet provided free plans would be enough but I am stalled without better knowledge.

Question by netlink    |  last reply


Differentiate different rats by size in tunnel.

Hey guys, I need some help.Is there any way to measure the different size - length or volume of rats as accurate as possible? I have an idea to put 2 ultrasonic sensor (in the beginning and in the end of the tunnel) so it will be able to measure the length and calculate the size.Or is it possible to do it with volumetric sensor or something else? Thanks!

Topic by DenislavM    |  last reply


Electromagnetic coil design, effect of wire AWG and turns.

I made coil of core length 28 mm and wire gauge 38 and 1850 turns but i am getting very less magnetic compare to other coil of core length 21mm, 28 AWG and 1000 turns. Could you please sujjest what might me the problem. And current we are giving is up to 0.5 A.

Question by ಗುರುತ    |  last reply