Excel Formula

Use this forum to ask questions about excel formula, answer them or to post your own finds

Posted by Fuzz666 4 years ago

Math formula(e) needed: tesseract model construction?

Although I CAN do this without the math formula(e) to figure it all out, I would like to have it for a quicker method of figuring out size, etc. so I didn't have to use up so much material in guessing. I would like to construct the tesseract I have pictured here, using rigid clear plastic sheets or panels.   Given a said size for the "inner cube" say 2 inches (approx. 5 cm or about 51 mm) what formula(e) must I use to calculate the panels' dimensions to connect to the larger cube (knowing full well this will depend on the size of the larger cube....say approx. 4 inches across (about 10 cm or 102 mm)? The reason I'd like the formula(e) is that I may need to increase the size of the center cube by an inch or so, and this would allow me to do so without having to go through the "trial and error" thing so many times. I would, of course, want the center cube to be "centered", if possible or shall I say as close as possible. Thanks....

Posted by Goodhart 7 years ago

math fromula

Thought this would be an appropriate place to share some of what i thought was interesting information to do with the area of a triangle and how numbers co-relate. To round off a square to 100cm square, one quarter of that area is 25cm square, (10cmx10cm =100/(div)25%=25cm), the area of a  right angle triangle with sides measuring ~7.0710cm,  equals ~25% of 100cm square,  25cm square of area,  (7.0710/2=3.5355 x7.0710=24.9995205). 7.5937 if it is an equilateral triangle. it is a standard size i use,  a handy measurement if you use templates for construction because it in  some way represents a metric increment, thanks, Kim (the formula i used is half the base times the height,  unless im mistaken i recall that is the correct formula?  though i am not a full time mathamatician.  for the equalateral triangle i used a web based polygon area calculator.)

Posted by QSDR 6 years ago

Need help with a lotion base recipe.

Hello, wasn't sure where to put this, and I didn't see a beauty forum.  Well. first of all. here is a formula for a lotion base that I tweaked. 8 oz distilled water 1 oz fresh aloe vera gel 1 oz floral water   1 tsp citric acid 2 oz glycerin 1 oz emulsifying wax 1 oz beeswax 1 oz shea butter 1 oz coconut oil 1 oz almond oil 1 oz avocado oil tsp essential oil 1/2 oz stearic acid I heard that 1 oz is about 2 Tbsp (tablespoons), but still not sure on this. It came out a bit thicker than I would like it.  I dunno if I should add more emulsifying wax, take out the beeswax, or both.  I need help making it less greasy feeling and a little thinner.  I made a batch I'm not sure what to do with.  I might just use it to repair those cases of dried out skin that appear around the winter season.  Any suggestions?

Posted by Crystalline_Chaos 8 years ago

SMPS formulas?

Are there any switched mode power supply formulas? I've been googling but I can't find anything... I need to know relation between duty cycle (I'm using square waves) frequency size (value) of the inductor output voltage output amperage how many amps should the inductor be rated for (is it how much your drawing?)

Posted by guyfrom7up 10 years ago

RPM/MPH formula

I'm designing an anemometer with Arduino and I need a formula to figure out the speed at which the rotor turns. I have a rotor with three magnets, spaced 71mm apart, triggering a Hall Effect sensor which the Arduino reads and counts. Now I can't seem to figure out a formula to calculate wind speed from this information. Anybody got an Idea (or the answer?)

Posted by smkoberg 8 years ago

International zero-emmission motorsports

The world's first international hydrogen-powered motorsport race was held in Rotterdam this weekend.Dubbed the Formula Zero championship, the contest pitted teams from five countries against each other in a zero-emissions go-kart race.Each team's entry was powered by a commercial fuel cell that produces electricity from hydrogen. It may be small-scale, with only six teams entering go-kart sized vehicles, but Formula Zero is an officially-recognised motorsport, with plans for scaling up to Formula Three and the Formula One style and speeds."In 10 years if the motorsport industry as a whole hasn't engaged in zero or low emission principles, it probably won't be around," said Greg Offer, who headed up the Imperial College London team. "Teams that embrace this new technology early on will succeed, and those that don't will fall by the wayside."Racing excitement won't suffer, though; Dr. Offer says that fuel-cell powered vehicles don't represent a compromise in performance over traditional petrol-fuelled engines.'"With a combustion engine, you have to reach three or four thousand revs to get your peak power," he says. "With an electric vehicle, it's all there from standing, and they're more efficient." The next races are planned for the US in March 2009. Plenty of time to get your own entry built.Imperial TeamFormula Zero homepageBBC news article

Posted by Kiteman 10 years ago


Http://babel.hathitrust.org/cgi/pt?id=mdp.39015026999022 the above link is VICTORY BEGINS AT HOME! RECIPES TO MATCH YOUR SUGAR RATION this next is the correct link, tested twice. babel.hathitrust.org/cgi/pt the following is OCR generated text, but there is a PDF read on-line only there too. The link to the catalogue was posted to the Internet Archive text forums today. NOTE, The PDF can NOT be downloaded to keep, just read on line. BOOK OF FORMULAS PREPARED BY THE EDITORIAL STAFF OF POPULAR SCIENCE MONTHLY RECIPES, METHODS AND SECRET PROCESSES GROSSET & DUNLAP • Publishers • NEW YORK COPYR1GHT, 1932 AU rights reserved PUBL1SHED JANUARY, I y J 2 SECOND ED1T1ON FEBRUARY, 1934 TH1RD ED1T1ON AUGUST, 1934 »On*TH ED1T1ON JULY, 1935 PUNTED IN THE UN1TED STATES OF AMER1CA

Posted by Lateral Thinker 8 years ago

Current measurement with arduino

Hey I try to measure current with hall-sensor amploc 25A, it sense magnetic-fields, offset voltage is 2.5V and I use arduino uno. I get 519 value from analog pin and 37mV/A is hall sensor sensitivity. My formula is outputValue = ((((sensorValue*5000.0)/1023.0)-2500)/37 multimeter shows 0.112amps when I put load but I dont gett correct value on LCD Is my formula OK?

Posted by mattilaniko 3 years ago

Ohm's Law watch...

Has anyone seen this?  "Ohm's Law Watch" For those of us that have difficulties with formulae, this looks like it might be handy :-)

Posted by Goodhart 7 years ago

Formula1 Parts 3D-Printed

Interesting story, they have family printers too http://www.corriere.it/english/13_maggio_14/formula-one_70300362-bc81-11e2-996b-28ba8ed4f514.shtml

Posted by economix 5 years ago

Diode Help

Hi, i have a bunch of diodes laying around, can somebody explain the diode function on multimeter? sure, there's numbers on the multimeter, but what do they mean? maybe give me a formula? Thank You!

Posted by Sandisk1duo 10 years ago

Battery power

I am attempting to calculate my amp need for my garage in order to set up a 12v battery system. Using the formula; Watts / voltage = amps drawn, I have hit a question. If using a 12v battery system and converting to 110v, should I be using 12v or 110v in the formula?Example; 100 watt light bulb / 110 volts = .91 amps. Nice!But if I use the 12v; 100watt light / 12v = 8.3 amps.I'm believing I would be drawing 8.3 amps from the battery to power this light.Plus the converter draw...Please tell me which is correct?

Posted by olddawg 10 years ago

mini batches of wine

Im gonna start making mini batches of wine to see what kinds im gonna mass produce.......is there a formula for sugar to yeast......im making them in pet bottles or cocacola bottles

Posted by rollingstoner357 10 years ago

Racing Game Physics

I've been designing a physics engine for a racing game for a long time now (months? years?) and I think that I've finally got almost everything figured out. The one thing that I don't know about is traction. So far my best guess for a formula is T = X + (Y * S)Where T is the stabilizing force on the car, S is the amount of slippage, and X and Y are two of the car's stats (probably measured in G's). This formula would be applied to each tire separately to account for the suspension.NOTE: The thing that might not be obvious here is that the car doesn't slip at all as long as X isn't exceeded.What do you think of this?

Posted by yourcat 9 years ago

ill from knowledge

Have you ever felt like knowledge is being crammed down your throat in School? Do you ever feel physically ill (like you're gunna thow up)? You're going to be tested later on something insanely complicated? Today, for me, in algebra 2, we are starting to learn about conix, and I feel ill. There are so many formulas, so many variables, so many variations, so much space to make a tiny error, I feel like I'm gunna die in math. Unless anybody knows an easy way to memorize a bunch of complicated formulas and how to use them ;) anyone ever feel ill from knowledge?

Posted by guyfrom7up 10 years ago

Post your pets!

Post your Pet's best Pictures!!! Formula: Name, Breed, details This is my doggie, his name is spicky. He's a mix, we don't know of what though.... He loves to pose for the camera!

Posted by Keith-Kid 10 years ago

Star Rating System Implemented

Instructables can now be rated on a 5-star rating scale. So instead of saying that you like an Instructable, you can now say just how much you like it! Some fancy mathematical formulas were used to convert the previous ratings to the new scale, providing the scores that you see now. These formulas will be getting tweaked as we get some kinks out of the system and fine tune the results, but all of the new ratings will be saved for more accurate results in the future. So for now, go out and use the stars to more accurately rate new and older Instructables! More ratings will help fine tune future searches and encourage more people to post better Instructables.

Posted by fungus amungus 10 years ago

Solar battery charging

Have been looking at the instructable on the micro solar generator, and wondering if there is a formula to calculate how big a solar panel is needed to charge a battery. I'm looking at maybe using a car battery to run some LED globes such as the one below on my deck, they run at 1w 8mA 12v. Any ideas?

Posted by dover1123 11 years ago

Caution ,danger message

A cordial greeting to the whole community; I would like to ask if there is a standard formula to alert the who is reading to pay attention to the dangers of electric current while you perform a job and at the same time to arise from any liability from damage caused by an incorrect or incomplete understanding of instructions step by step. thank  for help  

Posted by torx 3 years ago

Math Problem

I need a formula to answer a question such as this: If a 7 feet 300 lb man can have 24 beers before becoming intoxicated, how many beers can a 5 feet 100 lb man consume before becoming intoxicated. Or direct me to a site where I might have this answered. Thanks in advance.

Posted by Sovereignty 5 years ago

How much psi can these objects hold...

How much psi can a: 1. Coke Bottle 2. PVC Pipe 3. Metal Pipe safely hold? Is there a formula that I can use to calculate any vessel's psi capacity? Thank You!

Posted by La Tour Rouge 9 years ago

DIY Instructables Handbook

I just had a great idea, different instructables people should make different handbooks for different subjects that they are good in. Those types of books at stores are usually really overpice and have a ton of information that you'll never use and just makes the book fatter. I'm personally making an electronic on, fitting 4 pages on one 8 1/2 x 11 sheet, making each sheet of the book ~3.25" X ~4.5. If you make one please upload a pdf file so that others can download it, cut it, and assemble it to have a crafty pocket refrence!This is the table of contents of electronic book (so far):TABLE OF CONTENTSFormulas....................................Definitions andSchematic Symbols....................Conversions................................Prefixes.......................................Resistor Code.............................Capacitor Code...........................Inductor Code..............................AWG Specifications.....................General Electronic Tips...............First page:General outline:E=VoltsI=CurrentR=ResistanceP=Watts (Power)L=InductanceC=CapatanceG=ConductanceOhms Law: E=IRPower Formula: P=IEResistors in series: Rtotal=R1+R2+R3...Resistors in Parallel:Rtotal=(R1-1+R2-1+R3-1+.....)-1orstill working on it (and the subscribts and superscripts didn't translate too well, but you get the idea.If you have any formulas that you want me to put in the electronics reference then post a comment!Some topics for references could be:WoodworkingConstructionCookingRadioetc.

Posted by guyfrom7up 10 years ago

Need some input on boat propulsion

Can someone help me out with some ballpark calculation of propulsion power needed to move a boat? I do have some specific questions: 1. Propeller vs. Jet: Which one will deliver more propulsion given the same amount of power. 2. If it is typical electrical trolling motor type propeller, is there some simple formula to represent relationship of boat speed, power needed (hp), propeller rotation speed, and diameter of the propeller? 3. If it is a jet: Is there a simple formula to represent relationship of boat speed, power needed (hp), boat speed, and GPF of water to move the boat. I know that I am missing a few variables here like boat's weight and its water displacement.  I am trying to keep it simple. Any thoughts and input will be highly appreciated. Thanks.

Posted by kabira 6 years ago

How to write equations in posts

Sorry if this question has been asked lots of times on the forums but I couldn't find any answers for it. How can I display equations is a nicer way then just Gp(s) = 1/(tau*s+1) I tried using codecogs latex equation editor which showed the equations in the editor but on the actual post nothing shows up.

Posted by Roboro 2 years ago

how do you measure HV?

What's the best way to measure High voltage (I think my output is somewhere between 10kv and 50 kv)? Is there a formula for the spark length and humidity (I can measure humidity)? I need to buy an appropriate capacitor for my tesla coil, my initial HV is from an ignition coil.

Posted by guyfrom7up 10 years ago

Calling all Potato Gun Aficionados and wanna be Combustion Scientists

This is message to anyone who enjoys hearing the sound of forced combustion, or better yet, the loud crack of a potato gun being fired. My co-conspirator and I are in need of some mathematic assistance. Ideally we are looking for a “magic” formula concerning barrel length to blast chamber ratio for optimal performance. The ideal fuel would be propane or butane. We have been using a 4” by 33” blast chamber coupled with a 3” by 44” barrel. So far, we have had significant success with this combination, but are curious if there is a better ratio to use. With our current specs, we are able to shoot a 3 – 4 lb. ball of plaster over 250 yards (this is the carry distance, not the total distance traveled) at a 47 degree angle. If anyone out there knows a formula or has advice on Blast Chamber to Barrel ratios we are greatly interested to hear what you have to say.

Posted by benihana 10 years ago

Electronics Help

Hi ppl,I am currently making a variation on this circuit:http://www.edn.com/article/CA257052.htmlhttp://www.edn.com/contents/images/257052f1.pdfI understand how it all works but do not understand the principle of the inductor capacitor used (bottom left), if anyone could give a brief explanation of this (links are good too) and also some formulae i would b e very greatful!!thanks

Posted by drummer ian 10 years ago

Electrical Circuit Help

I would like to make the LEDs in the pre-wired controller in the first picture shown blink to music using the formula in the second.  I was thinking that I would need to leave the +/- coming out of the controller on different power than the LED strips this way you have constant power to the controller and therefore the remote to control the colors.  Anyone know how I can incorporate this?

Posted by chunkyblamm 6 years ago

Calculating Pi using simple JavaScript

One day I was bored and wanted to calculate Pi for myself. After finding out the Leibniz formula for Pi. When it is solved for Pi one gets: Pi=4/1-4/3+4/5-4/7... And so on since it's an infinite series. Since one can see a pattern that can easily be defined I concluded that a simple program using a loop could be made. I decided on using JavaScript for its ease of use and use a for loop. The program I made at first was mainly: var Pi=0; var n=1; for (i=0;i<=1000;i++) { Pi=Pi+(4/n) n=n+2 Pi=Pi-(4/n) n=n+2 } Where the variable "Pi" is the value of Pi, "i" is the number of times the loop is repeated, and "n" is just a variable to help in the formula. This I however found could further simplified to: var Pi=0; var n=1; for (i=0;i<=1000;i++) { Pi=Pi+(4/n)-(4/(n+2)) n=n+4 } Of course the more times the loop is repeated, the more accurate your value of Pi gets, and while 1000 may seem like a large number, the value of Pi which it calculated is wrong after the 3rd decimal point. I've had it repeat over 100,000 times and it gets more accurate, however, remember that making the number of repeats can slow down and even crash your browser (I speak from experience). If you want some ready made scripting, then here's some scripting I've made which lets you easily control the amount of loop repeats. It is based as an HTML document: //Made by Masterdude var c=0; function Calculate() { var c=prompt("Enter number of cycles:","0"); if (c>0) { var Pi=0; var n=1; for (i=0;i<=c;i++) { Pi=Pi+(4/n)-(4/(n+2)) n=n+4 } alert(Pi); } else { alert("Canceled or Error in input: Input must be positive."); } }

Posted by Masterdude 7 years ago

Slope Measuring

     I'm interested in making a yardage book for one of the golf courses i play at. The only problem is that i don't know an accurate way to measure the change in distance through elevation. For instance if a shot to a green with no change in elevation requires a 7-iron, then a shot of the same distance that is downhill should require a club that will hit the ball a shorter distance.       My question is, is there a formula of some type that i can enter the rate of change in slope and the distance, and get the actual distance needed for the shot.

Posted by wenpherd 7 years ago

Hooke's law (my brain just reached it's elastic limit)

I was very daring and entered the intro to engineering class as my elective in my first year of highschool. It turns out that I am in over my head. I am always up for a challenge, so I am sticking with the course I am one of the 3 freshmen in the class. On the first day of class our teacher was introducing the class and brought up that we would have to use some trigonometry and other math that the freshmen have no learned yet but he is willing to help us out with that... Anyhow today at the end of class we were given a hand out about "hooke's law" because we had just done a lab where we attached weights to a spring. The paper is pretty straight forward about hooke's theory and the formula F= K (delta)L (Force = K times the change in length) it defines k as the "proportionality constant" which I do not understand. What is a proportionality constant? wikipedia says its a force or spring constant which I still do not understand. Wiki also gives the formula F= -K x (with arrows over the k and x). help please!

Posted by astrozombies138 10 years ago

A new trick for the oogoo fans..?

Would folks who have played with Oogoo please try out the formulation at the link below:                                                           Noogoo and let me know if a) it works for you too; b) whether or not there are any differences/advantages over the initial Oogoo formula; and 3) you can see any applications for it different from standard Oogoo? It's not a published Instructable yet, I want to make sure there's something here worth using before I make a permanent post of it. Thanks, G

Posted by gtoal 7 years ago

LED calculator

Is there an easy formula or an online calculator to figure out what type of resistor I would need to hook up to an LED to keep from blowing it? I know you can also have a string of LEDs and the more you use you won't need resistors. I'm just trying to figure out for different projects with different batteries, what the most efficient circuit would be. Also what does T1 3/4 mean? I noticed that on the 5mm LEDs. How does it differ from ones without a designation?

Posted by mrshow555 11 years ago

Volume of gas from given weight of dry ice?

I'm rusty on basic chem. specifically, molarity, molecular weight... Dry ice, frozen CO2 is sold by the pound. I'd like to know by working formulas, how much volume a pound of dry ice will fill once it returns to gas. Carbon has molecular weight ~ 12.  Oxygen ~16.  But I don't recall what those numbers represent. One mole of gas occupies 22.4 liters, but how much does a mole of CO2 weigh?

Posted by Toga_Dan 4 years ago

Calculator Programs for Math

I've been working on some programs for my calculator recently and have decided to share them. I made these myself from scratch. If you want to modify go ahead just credit me. Don't sell them. And don't use them in math class if your teacher says not to. The programs are a follows: a quadratic formula solver, parabola solver, slope of a linear equation finder, and y-intercept finder. The programs work on TI-83's and TI-84's. If you have questions on how to use them or how to put them on your calculator please leave a comment!

Posted by sardines454 11 years ago


I need help. I need a way to (using optics) build a rangefinder that I could use to aim my air cannon over long distances. How would I judge the distance away from my target? Could I use lasers? Mirrors? Lenses? And once I judge how far away my target (to be drenched with a water balloon) is, then what? How will I know what degree of elvation I should angle my cannon at? Is there some mathmatical formula I could use to make a chart that I could just look at and adjust my gun? How could I build this?

Posted by MattGyver92 9 years ago

how far can an electromagnetic field reach?

For my project I need to know how far electromagnetic fields can reach. I am guessing its related to power and materials, but perhaps there is some kind of rough formula for calculating potential reach? By reach, I mean, how far can the magnetic field reach and attract (move) something, like metal fillings. Also, is there anyway to know how quickly a magnetic field can move something. In other words what speed will metal fillings move at when the electromagnet is switched on? Thanks all, Joel (the snow athlete)

Posted by snow athlete 9 years ago

How to convert analog MQ4 sensor output to ppm

Hi everyone,  My final year engineering involves a rover that can sense methane gas. Initially the idea was to just detect the gas as digital input but now i wanna do a bit more. I've searched all over the internet on how to convert the analog values to ppm, but couldn't understand any of it. I'd be really great-full if someone could give me the formula or the code to do this.  I don't intend on calibrating the sensor to find precise answers, just a rough picture of the ppm values is enough to begin with. Thanks a lot in advance. 

Posted by ZeeshanA27 2 years ago

Finding the altitude of a ball using weight and time airborne

I was shooting my tennis ball cannon today, and i was wondering if there was a way to find out the altitude of the ball using the time it was airborne and the weight of the ball. I have no idea how to approach this, i dont know of any math formulas that we've learned so far that can compute this. I think it would have to factor in drag, gravity, the weight of the ball, and how long it was in the air. I just dont know how to do it. If anyone with a better understanding of physics and mathematics can help me out, or point me in the right direction, it would really help me out! thanks!

Posted by John Smith 9 years ago

What helps an instructable get featured?

I created my first instructable a week back which is a binary clock: https://www.instructables.com/id/Cwik-Clock-v10-An-Arduino-Binary-Clock/ I was hoping to get it featured as I thought it added on to the regular binary clock formula (using potentiometers, and analog meter, focusing on accuracy, etc.). Today I saw a binary clock get featured (this one https://www.instructables.com/id/Connect-4-Binary-Clock/ ) which actually uses my code (which I put that code in public domain), and only has a subset of the features mine does. I'm trying not to be a bit jealous here :P. For the future, what helps an instructable be featured? Thanks, Dennis

Posted by cwik 6 years ago

How to Identify or Measure Inductance?

I am gathering the parts for an ible, but I am short one part: a 12mH inductor.I can spot some inductors in electronic garbage - the wire coiled around a ferrite loop - but there are also solid state inductors. Plus, the inductors are not usually labelled with their values.How can I measure the inductance of an inductor with a volt-meter and an ammeter, but without access to a sine-wave generator?Is there some simple trick that would get me "close enough" to the true value? What would be really useful (but probably doesn't exist) is a chart or formula where you plug in the size of the core and the number of turns around it and out pops the inductance value. ?

Posted by Kiteman 10 years ago

Chmistry buffs: IR invisible ink?

Hey all science-type people, I've seen invisible ink pens and things for sale that contain ink that show up in infrared, instead of ultraviolet light.  That's really appealing to me for a number of project ideas because digital cameras pick up IR exteremely well (especially with their filter removed). The problem is I think I'm going to want a lot of it, and those dumb little pens are crazily expensive. So any of you chemistry buffs out there have a secret formula I could make?  I'd prefer something invisible in regular light, but hey, whatever you've got. :) Thanks in advance for your help, -Kurt

Posted by PS118 8 years ago

spec a dc motor for a vehicle

I am making an electric vehicle. Assume no friction on a flat surface. The vehicle will have two dc electric motors preferably 24v or 48v system as space is an issue(about 3.5 x 4 feet) one motor on each drive axle. The vehicle will weigh 2000lbs have a max speed of 10miles per hour be able to reach max speed in under 5 seconds overall wheel diameter will be 16 inches Can be geared down to attain needed torque but must go up to 10miles per hour. Please include formulas so I can at least know how to do this in the future. I need to know power, torque, rpm needed for electric motor. Thank you

Posted by tshaf 1 year ago

Hoax? A task not only for high-schoolers...

       Well, exept for being quite a fun thing to watch, it also should work as a great Physics problem for someone like me (or a bit younger)-studying all sorts of Mechanics and Newton's Laws to work on... The task is to estimate the acceleration the motorcycle should have to do it, and whether it's significantly larger than the one stated in some technical data (there is the motorcycle model somewhere in the video's name).        If you have a go on it and are a) school-aged and b) not sure you are right, PM me. If you simply want to share your results and/or opinion, write here (but try not to put any solution-I mean formulas). In case the video doesn't work

Posted by gruffalo child 7 years ago

My other cars a Jet !

I just wanted to say SOMEONE HAS TO MAKE ONE OF THESE :DAt first glance, this looks like a very well-to-do neighbourhood. One in which Formula One racing cars, private jets, speedboats and the kind of equipment that any fledgling rock band would be proud of are left lying around in the garage.In fact, these utterly realistic images are printed on plastic sheets which are stuck on garage doors - the latest craze for home owners who want to not so much keep up with, as totally freak out, the Joneses.The weather and fire-resistant prints are designed to disguise that boring, flaky, greying metalwork. Held in place by industrial strength Velcro, they are easy to change and virtually indestructible.Source

Posted by spiritwolf7984 9 years ago

Can anyone help me make a co2 gel mask?

The more I read up on the benefits of using one of these masks the more I want to try one, it hasn't quite hit the states by storm yet but it will, too bad it costs an arm and a leg! I have an inkling of what may be required to make it, it's just a gel (glycerin) and co2 gas. I was thinking I could make one of the at home carbonators that several people on here have posted instructables on, but I wanted to be sure that it'd work in that manner. I don't think carbonating a liquid is the same as carbonating a gel. Another thing most formulas have in common is sodium bicarbonate. Any ideas?

Posted by gabys225 4 years ago

1000mph car to be powered by rubber and hair-dye.

The largest rocket fired in the UK for two decades will be lit soon, in the race to produce a land-vehicle capable of 1000mph. It will burn a mixture of solid propellant (HTPB, or hydroxyl-terminated polybutadiene, a kind of rubber) and liquid oxidiser (high-test peroxide, HTP, a highly concentrated form of hair-bleach) for 20 seconds. The Bloodhound SSC will also be powered by a jet engine from a Typhoon fighter. In the 20 second burn, the rocket will need fed with a tonne of HTP, so the pump is being powered by a Cosworth Formula 1 engine, which will become the only piston-engine running in a car at supersonic speed.  The team are planning to give the engine a major power-boost by feeding the supersonic airstream into the engine without slowing it to the usual operating speeds. The huge engineering challenges are being used to inspire students through the UK's STEM programme.

Posted by Kiteman 7 years ago

Smart board Using distance meters.

Hello! My name is Muneer. I was wondering whether this concept of making a smart board would work(shown in image). The idea is to use two distance meters to measure distance ‘a’ and distance ‘b’ from the transmitter in the pen to the top corners. Distance c is fixed and known. Using the distances, the x and y distance should be workable from the formulas(shown in image) I guess. I have a few concerns and require your expert opinion, a. How can we construct the distance meter (IR? Ultrasonic? Any available schematic...etc) b. Converting the x and y distances to pixel information c. Interfacing the board to a computer, possibly giving the input from the smart board directly as a mouse input. or if you could suggest other practical ways. Could you please help me with this? Thanks.

Posted by muneersn 9 years ago

Problem with ATtiny85 IR controlled LED

I am making a LED Light Stick with IR control to change the colour. Uploaded the schematics I made. Is there any mistake ? Do i misunderstand anything ? If yes, please forgive me, I am a complete noob and here to learn. I am going to add a 5v regulator to the Attiny85 power supply. And 380ohm resistor from pin5,6,7 to the corresponding transistor's base pins. I planned to use S8050 NPN transistor. How i calculate the things: 1. The RGB LED Strips i using is rated at 15W/metre @ 5V . Power supply i am using is 6V which is 4xAAA battery .I apply P=IV and get 2.5A/metre of current. Then I calculate current used in 60cm of LED Strips (2.5/100*60) and I get 1.5A current per 60cm. I devided the value by 3 and get 0.5A for each Red, Green and Blue pin. 2. Next step, I found the S8050 DC current gain (hFE/Beta) which is 40 and apply the formula Ic/Ib = B (Ic = 0.5A , Ib = unknown, B=40). I get the Ib of 0.0125A. Which mean i need 0.0125A of current in order to Fully-On the transistor at Ic=0.5A @ 6V. 3.To find the resistor value from Attiny85's Pin, I apply formula Ib = (Vb-Vbe)/Rb (Ib=0.0125, Vb=5 because the power supply of Attiny85 is 5v not 6v , Vbe=0.7V , Rb = Unknown) and i get value of Rb = 376ohm approximate to 380ohm. Another issue is that i didn't really know how to write the code. analogWrite seem didn't work for ATtiny85 sincce there's just 2 analog output for the controller. Or delayMicroseconds will work ? But i could'nt figure out how to write the code. I am very new to arduino. I know i should start at the basic first but i really need to get this project done. And please forgive my language. I didn't know English very well. Thanks a lot.

Posted by Sooncheng 1 year ago