speed of light?

I want to know the derivation of relative velocity formula used by Albert Einstein to prove that nothing can exceed the speed of light. Is there any simple derivation? please help

Question by deepakmurali 7 years ago  |  last reply 7 years ago



Sequential Lighting

I am looking to create a string of LED's that can be programed to turn on and off sequentially over 100 meters that can show the speed of a runner over that distance. ex: 100 meters in 9 seconds. any ideas, also re-program the same to different times.

Topic by ScottR148 2 years ago  |  last reply 2 years ago


Why does light move? Answered

From the theory of relativity, we learn that time is relative to the observer. And that time starts going slower and slower as the observer (reference point) moves faster and faster. And if the reference point reaches the speed of light (c), time stops, and if it theoretically surpasses it, time would go backwards. Now, light travels at the speed of light, so if we consider a photon as the reference point, isn't time still for it? And if time is stopped, how does the photon ever get anywhere?

Question by ricardjorg 8 years ago  |  last reply 8 years ago


Frequency driven speed for chase lights..?

I have some battery operated chase lights (Christmas lights) that I want to wrap around a musical instrument.. When I play a note, I want the frequency of the note to drive the chase light speed. So higher notes will make them chase faster than lower notes.. How can I do this?

Topic by 3DPiper 5 years ago  |  last reply 5 years ago


What would the approach of a black hole do from an atoms perspective?

IE on an atomic scale. Would the atom get stretched out or torn apart at all? What if the atom were traveling at lightspeed directly at or sideways to one? All google is giving me is silly micro-BH stuff and absolutely nothing relevant.

Question by The Ideanator 6 years ago  |  last reply 6 years ago


Can we stop time of any body by stopping it's movement through space? Answered

Hello! Please read the whole details before answering.  I was searching on the internet on "Is time passing by around us or are we moving through time?". I found an article, it said that after the bigbang, the four dimensions were created instantly, three of space and the fourth one was said to be time. It said that the bigbang provided energy to everything in the universe so everything in this universe is constantly moving outward from the point of bigbang. So as it is moving through space, it is also moving through time. Now I don't know if all of that was true or not, but if it were true, than if the movement of anything through space is stopped then it should also stop moving through time as well. And also from this explanation I don't understand that how would "time not exist" for bodies moving with the speed of light through space, whereas they would also be moving through time as well with a faster rate and should "age" more quickly. So can you clarify this please, thanks.

Question by Wisaam 6 years ago  |  last reply 6 years ago


Question regarding speed electricity

Hi people! I have another thing which i do not totally understand, so as usual i have asked in one of my favourite sites! :) I always had a doubt on how "fast" is electricity. In our real world, i can observe that it is pretty fast. If i turned on a switch connected to a light bulb, i can see it turned on pretty much "instantaneously". So a question came to mind, how fast it really is? Is it near to the speed of light? So, i did some googling. According to what i have found and understood so far, it is the electric field that carries information and not the electrons themselves. And electric field travels near to the speed of light( of course, depending on the medium).  If that is the case, then from the "textbook" definition of electricity, it is the movement of electrons right? But according to what i have understood so far, electrons move pretty slowly. In DC a few millimeters per hour or so(not having the exact figure in mind, pardon me) and the average displacement in AC is zero. Then how exactly is electricity so fast? I would appreciate it if someone explains it in a simple way, both on speed and what exactly is movement of electrons. :) Update: Okay, so far my questions are answered, and it seems to take off in different directions(like science always does :D). So to stay true to the question posted here, i would like to say my doubts cleared! Many thanks to people who have answered my question, Specially Dr.Kelsey and Josehf , for the information provided! I will post other doubts in new topics.

Topic by charmquark 6 years ago  |  last reply 6 years ago


230vac extract fan speed control - help

Hi I'm just in the process of refurbishing the bathroom of a flat I bought. It's all been plastered out already and I realised I've no extract! So, I created a plenum at hi level and mounted a fan under floor and have ducted it out. I want to run the small AC extract fan 24/7 at low speed (kinda tick over speed) and then switch it to hi speed when either the humidity goes up (cos the shower is running) or the light goes on (assumes someone's using the WC!). I can't get to the lighting wiring so I'll need to sense that remotely. I can fit a humidity sensor in the duct work. I've tried everywhere to find something suitable with zero joy. Is anyone here able to point me in the right direction?

Topic by ListysDad 7 years ago  |  last reply 7 years ago


I need to know about the speed of sounds.? Answered

If you yave a gunshot it is going at the speed of sound.  If you shoot two guns at the very same time with really no time difference then they, the sound, would be going twice the speed of sound.  then if you had two flashlights and turned them both on at the same particle of time then would'nt they be (the light that is) be moving at twice the speed of sound? This means is I had a mirror that had 100 percent reflection i could reflect back the light and it would get there before it left the bulb and if I had a really efficient photocell it could power itsellf and only need a battery to start up.Maybe I could even start it by flashing a strobe flash from a disposable camera at it.  Can somebody give me a link for the best photocell you can find.

Question by i-want-to-know-it-all 8 years ago  |  last reply 8 years ago


Slowing a motor

I have a 4 Watt mains powered motor that currently spins at 1.6-1.9RPM. I need to find some way of slowing it to maybe 1 revolution every 10 minutes. It's all sealed in a metal case and connected to the mains by a standard plug. I really need to find a way to do this without breaking it apart stuff as it may need a safety test later, I looked at dimmer switches as they essentially limit the voltage and are a max of 300w. Like this - http://www.jpgelectronics.com/products.asp?partno=350.109 I realise that they are made for lights but it's a similar principle and is only about £6. Would this work? Are there other options if I don't want to break into the motor housing or wiring? Thanks.

Topic by happysnail 7 years ago  |  last reply 7 years ago


Can you change the shutter speeds for any camera? Answered

I was looking to do light doodles and i decided to get a new camera

Question by Chromatica 9 years ago  |  last reply 9 years ago


Looking for an incandescent light fader? Answered

Looking for instructions on how to build an incandescent light fader.  Want to be able to control the speed of the fading.  Want to be able to control about 6-12 40-60 Watt light bulbs.

Question by tapatio 6 years ago  |  last reply 6 years ago


Salvage the light barriers of an old mouse to use it as a lightbarrier eg on the left mousebutton ?

Is it possible to salvage the light barriers of an old mouse to use it as a lightbarrier eg on the left mousebutton ? It would be interesting for counting small insects! ANTS! In old ball-driven mouses there are two small "light barriers". They are interrupted by punched discs. Is it possible th wire the receiver of the barrier to substitute a regular mouse button? It would be wonderful having two lightbarriers on one USB/PS2 port! Thank you! PeerTeer teerpeer@web.de

Question by peerteer 9 years ago


Speed Control for AC Electric Motors

Can anybody tell me how to build a controller to adjust the speed of an 110VAC electric motor, ( ex: blower motor, fan motor ) I was cautioned about using a light dimmer. bill

Topic by broham 12 years ago  |  last reply 2 years ago


k-line arduino project, speed and brake light

Hello. I have a simple task to achieve, I guess, but I'm stuck. I'm using the setup from the attached image. All I need to do is to read the Speed of the vehicle using data from the obd2 k-line pin, and then to send a command to blink the brake lights when a certain decrease in speed is detected (e.g. more than 2km/h/s). I can not initialize the k-line and I am not able to red anything on the serial monitor on arduino :(. After I manage to read the raw data I am planing to figure out what's the code for turning on the brake lights by just simply pressing the brake pedal. The vehicle is an 2004 BMW E60, but I guess this is not an issue. Question... Are the TX/RX pins connected as it shod on the arduino board? Thank you. Ant help would be appreciated. I need this for a school project and a have a deadline :(((

Topic by CatalinP8 1 year ago


Help Motor Control!

Hey guys, I need to create a motor that can have a fader/dial so that I can control its speed (rotations). I figure it must be a simple enough system but I don't even know where to begin in terms of parts. I just need it to be strong enough that I can spin a GoPro camera (fairly light - but not toy car motor weak). Sincerely, Alex

Topic by mrmadsci 6 years ago  |  last reply 6 years ago


I Need Some Lighting Help

I've hit a little speed bump. I need a bright, preferably diffused, soft white light for high speed videography. It cannot be florescent or a CFL (see why below). I can't seem to find any lights that fit these standards that aren't florescent, but I know they exist. Can you help me find a suitable light?

Topic by Spl1nt3rC3ll 10 years ago  |  last reply 8 years ago


What should I try taking high-speed photos of? UPDATE1Apr10

I took the two photos below last year, and I want to try a few more for a new project. My rig is simply the flash unit out of an old disposable camera, rigged up to a microswitch. For the falling coins, they landed on a tilting platform with the switch underneath, so that the first coin to hit bumped it down into the switch and fire the flash. The droplet was just by setting the faucet to drip and poking the switch manually and getting a lucky shot. I'd like suggestions for what to try photographing next. I'd prefer something that can activate the flash by simply pressing two contacts together (i.e., a switch), as I haven't had much luck building light- or sound-activated triggers. UPDATE so yeah, I totally this in before spring break and forgot to mention it. The project was a magazine cover, don't knock the radd grafics dezine skillz.

Topic by CameronSS 9 years ago  |  last reply 8 years ago


High Speed Suggestions- More Please!

As you may know, but need reminding of, Summer is just around the corner! This means that I will have plenty of light and much needed free time! Geocaching and iBling aside, I plan to get some excellent footage this summer. Only problem is, I need ideas! So, what would you like to see filmed at 300, 600, and 1200 frames per second? (I decided to post a second topic, seeing as my first one is a little crowded.)

Topic by Spl1nt3rC3ll 9 years ago  |  last reply 9 years ago


How do I wire a speed control with a a blinker using 110v indicator lights ?

I have 15 110v  red indicator lights and need to light these one at a time using a speed control  and blinker control to simulate a heart beat. This monitor is the same that you can see in the Classic Monster Movie ,"The Bride of Frankenstein". Any help would be appreciated very much.?

Question by 1stcontact 6 years ago  |  last reply 6 years ago


I need help!

Greetings! I have never built an electronics project like this, however, I do understand the basics of what needs to be done. We are building a car that will run on the Bonneville Salt Flats in 2010. What I am looking for is to build a device to show the difference in wheel speed between the front wheels and the drive wheels. The reasons for this is to give the pilot information on how much traction he is getting at the rear wheels. Since the engine and drive wheels are located 15 feet behind the driver, you cannot do this by ear (especially at 400+mph). The second reason is that the tires used at these speeds cost $800 each, there will be 4 drive wheels, that's $3200 worth of tires. Because of the speed, the tire treads are very, VERY thin, any spinning will destroy the tires in short order. It's not just a money thing, at 400+ getting a flat tire could be fatal. My current thought is to place wheel speed sensors at one front wheel and one drive wheel. That data will be collected and one value subtracted from the other. That difference will be presented to the pilot. I am not opposed to an LCD display or a series of lights that will indicate 5, 10,15, 20 and over 25mph difference. I am a computer programmer by trade and we are planning to integrate a PC into the car for data logging and tuning. I will have a complete CPU available managing the input and output. If we can use the PC to create an application to do this, it should not be an issue. If it is easier/better to build a chip-set to do this, we can go that route as well. I am open to any and all ideas, I have a rough idea of what needs to be done, just no knowledge of parts or processes to complete it. Thanks, Brandon.

Topic by bbarn 9 years ago  |  last reply 9 years ago


flexible light rope or similar light moving device

Am searching for method to replace old or upgrade new idea for creating safe toy which allows child to operate from control box or reistat the movement of color lights through safe tubing- similar to light rope but changable through speed and direction. Mostly speed. Enough rope to shape into any form. thanks, west virginia kate

Topic by west virginia kate 11 years ago  |  last reply 11 years ago


why do light have the tendency to manage time?

The speed of light is different in different mediums.when light enters in a more or less denser medium,it is deflected from its path,that is,it changers its path.it does so to maintain that time which would be reqired to cover the same distance in the absence of that medium.the question is why does light do so?,e.i.why light manages its time?  

Question by vmkverma 8 years ago  |  last reply 8 years ago


How do you control 2 motors, 4 servos and 2 stepper motors for a RC airplane? Answered

For the upcoming Epilog challenge I was wondering if there is a 4 servo 2 motor controller for a R/C airplane.If there is can you give me the specifications on what to look for? Is there also a way to control 2 stepper motors from the signal from the transmitter, it has to be semi-light, or light enough for a RC airplane. How could a program both the motor/servo control and the stepper controller?

Question by squirt8500 10 years ago  |  last reply 10 years ago


12v Electric Motor Speed Control?

I have a 12v electric motor I was given from a camper water pump (at work currently so I don't have any of the specs). I also have a power supply from an LED lighting kit to take the power from a wall plug down to the 12v for the motor. Connecting them directly works fine, but I am trying to make an electric leather burnisher and would like to have a bit of control over the speed of the motor. I have a small 25 ohm rheostat I wired in, and it worked perfectly, but the rheostat began to overheat with in a few minutes. What type of controller would I need to look for? Just not sure where to look when it comes to items like that.

Question by dbgrigg189 2 years ago  |  last reply 2 years ago


the distance of others planets measure with tausends of years of light speeds. Answered

How come a ufo creator on board reach to earht.are thair life too long to do it?

Question by tayyareci 10 years ago  |  last reply 10 years ago


[newsletter] Light Bulb Lamp, Predicting the Weather, Chocolate Speed of Light...

June 19, 2008 Sign-up for this newsletter: function openSubscribePopUp(src){ var emailValidate = /\w{1,}[@][\w\-]{1,}([.]([\w\-]{1,})){1,3}$/ if(emailValidate.test(src.value) == false){ alert("Please enter correct email"); return; } window.open("/newsletter/newslettersignup?email=" + src.value,"newslettersignup1","status=yes,scrollbars=yes,resizable=yes,width=420,height=250"); } Welcome back! Want to put some insanely cool, lights on your bike? Then enter our Let It Glow! Contest. The prizes are super sweet and blinky, so enter before the contest closes this weekend! RoboGames 2008 is over for this year, but you can still enter our Robot Contest to win a trip to RoboGames 2009! Air fare, hotel, and entry fee are included!Winners have been announced for the Discover Green Science Fair for a Better Planet Contest. See who won, and bookmark some Earth-friendly summer projects! Check out these cool Instructables! DIY Vinyl Wall Art Liven up your apartment, without risking your deposit, by putting up some slick-looking ConTact paper designs to decorate your walls. posted by britsteiner on Jun 17, 2008 How To Measure the Speed of Light... Using Chocolate! Enjoy some gooey warm chocolate and learn some science at the same time! posted by bradpowers on Jun 13, 2008 Building Small Robots: Making One Cubic Inch Micro-Sumo Robots and Smaller With only cubic inch, you'll learn to be efficient in your robotic design. posted by mikey77 on Jun 12, 2008 How to make a piano keyboard Build piano keys from raw materials and make a piano you can truly call your own. posted by threesixesinarow on Jun 19, 2008 Steampunk Style Fan Cool off in neo-Victorian style with a custom built fan. posted by reluctant_paladin on Jun 13, 2008 Steel Centipede Turn that scrap metal and chain into a unique sculpture with nothing more than a welder and a bit of creativity. posted by Mikey D on Jun 15, 2008 LED matrix using shift registers Play with patterns of light and display messages on a custom LED matrix. posted by barney_1 on Jun 15, 2008 Predicting the Weather with Clouds Learn to understand what the sky is trying to tell you. posted by randofo on Jun 12, 2008 Instructables Robot -- Paper Model Print and cut out this template to make a papercraft robot of your very own! posted by =SMART= on Jun 13, 2008 Central Vacuum Retrofit Install a central vacuum system in an existing house to have quieter vacuuming and an external exhaust. posted by a.doovz on Jun 13, 2008 Rock Band Guitar Stand/Drum Support Tidy up your virtual rock star gear and keep your drums steady with this PVC setup. posted by evilbunnee on Jun 12, 2008 Win great books for your travel tips! Closes on June 29! Winners are up! Animating Multi Layered Engravings Take glowing etched acrylic to the next level with animated frames. posted by japala on Jun 18, 2008 10-minute electronic leather band Enhance a leather bracelet with a flashing light that can record and play back patterns. posted by craft-tech on Jun 14, 2008 The Lucid Dream Machine Control of your dreams with the power of flashing lights. posted by guyfrom7up on Jun 18, 2008 SketchUp, Inkscape, and Ponoko Laser Cutting Install this plugin and you'll have a free way to design in 3D and export your files to be laser cut! posted by flightsofideas on Jun 19, 2008 Light Bulb Lamp Put your dead bulbs to use by turning them into stylish oil lamps. Just be sure to put them in a safe place. posted by CYNICALifornia on Jun 14, 2008 Now go make something awesome, and I'll see you next week! - Eric Sign-up for this newsletter: function openSubscribePopUp(src){ var emailValidate = /\w{1,}[@][\w\-]{1,}([.]([\w\-]{1,})){1,3}$/ if(emailValidate.test(src.value) == false){ alert("Please enter correct email"); return; } window.open("/newsletter/newslettersignup?email=" + src.value,"newslettersignup2","status=yes,scrollbars=yes,resizable=yes,width=420,height=250"); }

Topic by fungus amungus 10 years ago  |  last reply 10 years ago


Do Ultraviolet rays travel faster than Light? Answered

Because Ultraviolet Rays have higher wavelengths than the visual light spectrum. Does that mean that Einstein's wrong, or did I miss something and am I stupid?

Question by Wasagi 8 years ago  |  last reply 3 years ago


Electrical components

Is there any components that set the minimum energy to pass through? When the energy is lower than the fix amount , no energy will be passing through.  I'm trying to make a project. I'll put a dynamo on my bicycle, and it will be connected to 3 LEDs. When I cycle in low speed, only one LED will light up. When I increase my speed to certain level, 2 LEDs will light up and if it passes a certain speed all LED will light up. Any idea?

Topic by GohC 3 years ago  |  last reply 3 years ago


making a Club

My father and I make model trains. In one of our buildings i want to make it like a club, with colour changing lights(hoping to use a 2 leg RGB. Im still new to designing circuits and wondering if there is some-one out there who could help me make a circuit that would allow me to control the speed in which the LED will change colours and also have a on/off switch. If there anyone out there who can help me feel free to e-mail me on here or at parker66@nzmail.net. Cheers Daniel

Topic by parker6611 10 years ago  |  last reply 10 years ago


Modding a clock to run at half speed (resolved)

I want to make a clock that runs at half speed, or atleast is slowed down. Is this possible to make with resistors or do I need to make twice as large gears to make it slow?Obviously, the first idea is to prefer over the ladder. I've managed to get my hands on the circuit board that produces the hertz pulse, and also a blueprint that shows that if you put a 1k resistor on the input, it still beats at 1hz. Should you maybe put a resistor on the other end, the output? And how big of a resistance should I use?(It also shows two diods, which are added, which is used to light up a LED)Pictures from JosePinoI appreciate the help, thanks!RESOLVED: http://www.youtube.com/watch?v=BMtoBKAzhgA

Topic by isudoru 11 years ago  |  last reply 11 years ago



How fast can you spin your Golf Ball?

I played around with some balls placed into the airstream of a little blower. Everything light enough just "danced" in the air like being hold on invisible strings. But not so much the golf ball! You would expect those dimples are good for reducing air friction but do they also offer stability in some cases by making the ball spin? Check this video I recorded while playing - to me it looks like with a proper nozzle there is even more speed possible. https://www.youtube.com/watch?v=014QkXuTL0o How fast can you make it spin?

Topic by Downunder35m 2 years ago  |  last reply 2 years ago


LED light from wind turbine

We are playing around with various basic LED lighting from a small wind turbine and have a couple different ideas about how to build.  But we are wondering what the voltage range LED lighting can handle?  Even a small turbine can create a wide range of wattage based on the speed of the wind, at what point are we going to be doing damage to our lighting?  Do we need to come up with some sort of wattage dampener/regulator between the generator and the lights?  Simplicity is key in our design.

Topic by Two Paddles Design 3 years ago  |  last reply 3 years ago


Why do the constituent of white colour have different wavelength?

When white light passes through a prism,it is splitted into its constituents colours due to the difference in the speed of different colours in prism.the colour which has more speed is deviated most(red)and the colour having less speed deviates least(violet).thus,white light is splitted. we know that wavelength is directly proprtional to speed. The question is why the wavelength of different colours differ from each other?and why does the wavelength of red colour is longest and of violet colour is shortest? 

Question by vmkverma 8 years ago  |  last reply 8 years ago


how do you make a photon (or light) clock?

ok thanx to all the people that replied to my previous question about a rpm meter but now i have a new one. i need a way  of measuring the distortion of time inside the centrifuge and out side i have heard that the only way to do this is measuring the speed of light over a predetermined distance but i cannot find a way of duing this because light moves so fast and no processor i hav vome accros can do this so im asking how do i measure the speed of light.

Question by lj123456 8 years ago  |  last reply 8 years ago


Looking for a motor and some LED lighting

I basically want to build a rotating display stand; I need to find a motor which can move ~ 2-8 pounds at a speed of 1-12 RPM (preferably adjustable). I also want to find some LED lighting which I can embed in the base, which will have somewhere in the neighborhood of 1,500 - 2,500 lumens, without generating too much heat. I know there will be heat, of course. I just don't want to be at temperatures that would burn wood or melt PVC, as those two materials will be used a lot. Where's a good place to order these inexpensively? I'd like to build just one for now, but if it works out, I will be making several of these, possible a few dozen total. So bulk pricing would be a plus, but is not a critical issue.

Topic by karossii 4 years ago  |  last reply 4 years ago


Get the LED Out! Speed Contest Winners Announced

Instructables is happy to announce the winners of the Get the LED Out! contest. As this was a speed contest, all of the voting was done by YOU and (for the random prize) a plastic bin.To see the full list of entries simply check out the group. For a speed contest, the quality and quantity of the entries was pretty amazing and there are several that deserve to be looked at and appreciated. A big "thank you" to everyone who entered and showed us all the cool things that can be done with a tiny light.But enough about that... on with the winners!Pageviews and Ratings Prizes - For receiving the most pageviews and the highest ratings, the authors of these Instructables will each receive an Instructables Robot t-shirt, an Adafruit Industries TV-B-Gone kit, and $75 worth of LEDs from Phenoptix. Ratings Awesome led cube by AlexTheGreat Page Views LED Mood Jar! by joejoerowley Notes about the winners: While it is a great Instructable, Make your own Roll Up Keyboard was disqualified from winning a prize in this contest since the Instructable didn't involve putting any LEDs into the roll-up keyboard. Also, the Awesome led cube was the top of both lists, but was selected as the Ratings winner since it had the bigger lead in Ratings, by ratio, over the second than it did for Page Views.Ratings Prize Runners-up - For receiving the next highest ratings, the authors of these four Instructables will each receive an Instructables Robot t-shirt. Cat Burglar Joule Thief Desk-top Soldering Press! (with L.E.D) LED Light Drawing Pens: Make an LED Blaster Random Prize - For being lucky enough to have its name pulled out of a plastic bin, the author of this Instructable will receive an Instructables Robot t-shirt, an Adafruit Industries TV-B-Gone kit, and $75 worth of LEDs from Phenoptix.and the random winner is...this heartfelt Instructable.

Topic by fungus amungus 11 years ago  |  last reply 9 years ago


can I use a rectifier as a dimmer for halogen light bulbs?

I am wiring a custom exhaust hood, and am wondering if I could use a IN5402 rectifier diode rated at 3 amps, 200 PIV connected in series with a 1.9 amp halogen light load, running at 120 Volts AC in order to dim the lights in the hood at about half bright? Wondering specifically if I will run into any problems with the longevity of the "dimmer", or the life of the bulbs? Also wondering if any one might know how I could make a very simple circuit that could slow a fan down to about half speed. I am using single pole double throw bat handle switches to make a high and low setting. High will just go straight through, and low will go through the dimmer or speed reducing module. Thanks rik

Question by wirepig 7 years ago  |  last reply 7 years ago


how can I manipulate the space time continum to win the lottery? Answered

I just want to win the lottery  :)

Question by elmarco38 9 years ago  |  last reply 9 years ago


Motor Speed Controller. I have recently purchased a 115v Bodine Electric 42R Series AC Induction Motor

 I want to be able to control the speed of this motor to use for my homemade brass reloading tumbler. I am currently using a cordless drill which is not practical for the lenght of time the brass must tumble. http://www.youtube.com/watch?v=cvunTv-5x7A The specs for the motor are as follows.. 42R Series AC Induction Motor Standard Features Totally enclosed IP-20 rating. Fan cooled for high output power. Class "B" insulation system operated within Class "A" limits to prolong winding and lubricant life. Aluminum center ring and end shields for high thermal efficiency and light weight. Permanently lubricated, noise tested ball bearings. Locked bearing design minimizes shaft endplay. Application Information Capacitor is not included. Order with motor if required. Models are available with either NEMA C face mount or base mount. Any suggestions would be greatly appreciated.

Question by ehays 8 years ago  |  last reply 8 years ago


Fitlight trainer using arduino

I want to make a fitlight trainer with arduino. I want to make it with leds and LDR ligtht sensors. A random light pops up and when you hover over the sensor it sets it to LOW and then another random light pops up and over and over. Can anyone help me with this idea? I have the code for one light: int LDR = 0;     //analog pin to which LDR is connected, here we set it to 0 so it means A0 int LDRValue = 0;      //that’s a variable to store LDR values int light_sensitivity = 20;    //This is the approx value of light surrounding your LDR void setup()   {     Serial.begin(9600);              pinMode(13, OUTPUT);      } void loop()   {     LDRValue = analogRead(LDR);      //reads the ldr’s value through LDR     Serial.println(LDRValue);       //prints the LDR values to serial monitor     delay(50);        //This is the speed by which LDR sends value to arduino     if (LDRValue > light_sensitivity)       {         digitalWrite(13, HIGH);       }     else       {         digitalWrite(13, LOW);       }   }

Topic by JordyK4 3 years ago  |  last reply 1 year ago


time travel? Answered

Well i have a theory, but don't know if it's right. according to timedilation, time will go slower for you if you get closer to light speed. if you want to completely travel around the earth with light speed, it would only take 40.074000 : 299.792.458 seconds, which is 0,13367247550970745234691661255868 seconds. so you would experience it as 1.3 seconds. but because time for you goes very, very, very slow at that moment, the 1.3 seconds could be more then a million years! so, here it comes: if you travel so fast that 'your' time goes very slow, then the actual time would be more then if you traveled at normal speed. is that right, or am i completely wrong?

Question by necropolian 9 years ago  |  last reply 9 years ago


binary clock runs to slow, how do i speed it up? Answered

I made a binary clock from an instructable on this site: https://www.instructables.com/id/Binary-Marble-Clock/ but it turns out it runs WAY to slow.i wanted to know how good it ran, so i made the time 23:29 (current time then) and went to sleep. at 09:45 (not extactly) the clock gave about 00:30how do i make sure it runs like it should? couse now its being used as a light decoration...

Question by godofal 9 years ago  |  last reply 9 years ago


Flashing LED usb

I'm not really sure where to start with this, but in the end I's like an LED strobe where I can control how fast is flashes precisely (for example 5khz). My Ideas so far is you have an LED hooked up to my laptop via usb with a simple program to control the speed and how many times it flashes. Right now I've got LED's and usb's and 100ohm resisters if i need them. From what I've read I don't think I can control the usb port's power so I'm assuming I need a driver board or something? I'd love some help with this but I assume I've been too vague, mostly because I'm not sure what i'm talking about. Any help I can get would be amazing. Thanks

Topic by mitchpope93 5 years ago


Severe Windows Vista Home Basic laptop problem?

I just turned on my Vista and it made all the usual sounds of the fans and hard drive. The lcd screen was black and the caps lock light was blinking at a pretty fast speed. So i waited and nothing happened. The light just kept on blinking and the lcd did nothing. What do i do?? Please help me!!!!!!!!!!!!!!!!

Question by sci4me 9 years ago  |  last reply 9 years ago


Hammerhead Glider Z Prototype coming soon

Hammerhead glider Z Prototype coming soon. Z Prototype vs II # A lot faster than II like in lighting speed. # Heavyer. # Less glider.

Topic by wat. 7 years ago  |  last reply 7 years ago


Laser Rangefinder

A member PM'd me with this question, "hi im asking if i can use the arduino micro controller in distance measuring using laser" My response was "Laser distance is the time of flight of a pulse of light pulse that travels 3 feet in a single nanosecond..." https://en.wikipedia.org/wiki/Laser_rangefinder Do you think the Arduino can execute instructions at a fraction of a nanosecond ? What is the clock frequency of an Arduino ? . Take care of your eyes when using lasers !  

Topic by iceng 2 years ago  |  last reply 2 years ago


No idea how to make this LED Windmill

OK, I have an idea that sounds kind cool but no working knowledge of electronics. How difficult would it be to make a bank of wind powered LEDS? A circut that progressively lights up more leds as the wind kicks up to a higher speed?

Topic by Eye Poker 11 years ago  |  last reply 11 years ago