Workshop Topics

water conductivity meter

Hi does any one know how to build a water conductivity meter which measures in Microsiemens. as an added bonus i would like it to be able to measure other features of water quality such as the Ph value

Topic by tawcnysc    |  last reply

help killer homework

Help you have 3 hours to find the life cycle of a hermit crab for me i need a diagram and if possible adaptation though im ok on it. help help help help help

Topic by DELETED_Gavabc123    |  last reply

The Memristor - they've found it!

This came out quite a few days ago, but I haven't seen it until today.HP's Henry Williams and his group have accidentally stumbled upon the fourth fundamental element in electronics - the memory resistor, or memristor. Basically, it's a resistor that changes its resistance with elapsed current flow, or total amount of charge that has passed through it, and retains its resistance even after current ceases to flow through it. From the article:"The classic analogy for a resistor is a pipe through which water (electricity) runs. The width of the pipe is analogous to the resistance of the flow of current—the narrower the pipe, the greater the resistance. Normal resistors have an unchanging pipe size. A memristor, on the other hand, changes with the amount of water that gets pushed through. If you push water through the pipe in one direction, the pipe gets larger (less resistive). If you push the water in the other direction, the pipe gets smaller (more resistive). And the memristor remembers. When the water flow is turned off, the pipe size does not change.Such a mechanism could technically be replicated using transistors and capacitors, but, Williams says, “it takes a lot of transistors and capacitors to do the job of a single memristor.”The memristor's memory has consequences: the reason computers have to be rebooted every time they are turned on is that their logic circuits are incapable of holding their bits after the power is shut off. But because a memristor can remember voltages, a memristor-driven computer would arguably never need a reboot. “You could leave all your Word files and spreadsheets open, turn off your computer, and go get a cup of coffee or go on vacation for two weeks,” says Williams. “When you come back, you turn on your computer and everything is instantly on the screen exactly the way you left it. "Apparently, evidence of memristors has been around for quite a while, but it was only until now, during the age of nano-technological exploration, that we finally have labeled the "strange voltages" we've found in experimental circuits as a result of memristor behavior. The discovery was made while doping Titanium dioxide with some dopant that the article fails to cover. Anyhow, the resistance of TiO2 changes with the amount of dopant covering it. Since the dopant does not adhere perfectly to the TiO2 substrate, the flow of charges (electrons) can move the dopant, and cause it to cover more or less of the substrate, thus changing its resistance. "Williams found an ideal memristor in titanium dioxide—the stuff of white paint and sunscreen. Like silicon, titanium dioxide (TiO2) is a semiconductor, and in its pure state it is highly resistive. However, it can be doped with other elements to make it very conductive. In TiO2, the dopants don't stay stationary in a high electric field; they tend to drift in the direction of the current. Such mobility is poison to a transistor, but it turns out that's exactly what makes a memristor work. Putting a bias voltage across a thin film of TiO2 semiconductor that has dopants only on one side causes them to move into the pure TiO2 on the other side and thus lowers the resistance. Running current in the other direction will then push the dopants back into place, increasing the TiO2's resistance.HP Labs is now working out how to manufacture memristors from TiO2 and other materials and figuring out the physics behind them. They also have a circuit group working out how to integrate memristors and silicon circuits on the same chip. The HP group has a hybrid silicon CMOS memristor chip “sitting on a chip tester in our lab right now,” says Williams."I think this is pretty awesome, considering the current breakthroughs in nanotechnology and downsizing of transistors, memristors would enable a whole new field to be born, and circuit theory may have to be re-designed.Like Leon Chua said, the man who first came up with the idea of a memristor, "now all the EE textbooks need to be changed."These next few years in the field of EE should be very interesting =)Image from Spectrum Online

Topic by T3h_Muffinator    |  last reply

Robot goes on an airplane!

Robot and I went flying the other day, so we took a picture together. Whenever I wear it out in public, I hope somebody will come up to me and say that they're a member, too. Hasn't happened yet. I look a tad bit tired(/retarded)...since i'd been flying all day. EDIT: Yeah, I look really retarded in that picture...but at least Robot looks groovy!

Topic by Weissensteinburg    |  last reply

Dolphin Gets Prosthetic Tail

This dolphin was just a couple months old when it got caught in a trap and turned its tail into a useless stump. After a year and a half of recovery and building, she now has a prosthetic tail and has been swimming about with it. Nice. Link

Topic by fungus amungus    |  last reply

!!! JOIN HOT NEW GROUP !!! (LocaMoto)

Join the hot new group "LocaMoto" HOT HOT HOT AWSOME NEW GROUP

Topic by rickick    |  last reply

A basic (very basic) description of a Brushless DC motor.

So... before I start... I am not a physicist, nor am I an electrical engineer. Hopefully someone within one of those (or both) professions will chime in and enrich this discussion. That said... I'm going to be using leyman's terms. This thread is specifically meant to explain how a brushless DC electric motor exerts a force, and how that force is used to generate work. To start off, I'd Like to explain the components which comprise a brushless DC motor: First... You have an axil. The axil's purpose is to spin. Next you have natural magnets, or solid state magnet; I use the terms somewhat incorrectly, since a natural magnet refers specifically to nickel or ferrous base magnets, but there exist a large variety of compounds and composites that exhibit the ability to produce magnetic fields. In practice you have many in a motor, but for our purposes... we can pretend we have one. The natural magnet's job is exert a magnetic field while attached to the axil. After that we have an electrical coil. Once again, in Brushless DC motors, we have many of these, but for our purposes we'll use 3. The electrical coil's job is to produce a magnetic field which can move in a circle. Finally we have the engine housing. The purpose of the engine housing is to hold everything together. Note: I'm intentionally leaving out the computer control mechanism. there are alot of great instructables on microcontrollers. Most Brushless DC motors requrie one to work since there is no mechanical timing device, as there is in a brushed engine. So... how does this fit together? In this setup the natural magnet produces a force when next to the electrical coil (This coil is also known as an electromagnet). This is because the charge of the coil is opposite to the charge of the natural magnet. Once the Natural magnet and the electromagnetic coil align with each other, the first coil shuts off and the second turns on. Once again the natural magnet is drawn towards the magnetic pole. This process repeats until the natural magnet has spun in a circle (note: usually you want it to continue to spin beyond a single revolution.) That's the basic (very basic) idea behind a Brushless DC Motor.

Topic by Qcks    |  last reply

underwater sparkler

Is this real?CLICK HEREfor some reason i cant add the video if anyone wants to try, calcium chloride is basically water hardener

Topic by budsiskos    |  last reply

Flugtag -- human powered flight?

Have you seen the videos for Flugtag? It looks like a great excuse to build something fun and jump in the water, and maybe fly a few feet too.Most of them look like this: And here's the US record holder, at a whopping 155 feet: I bet we could do better than that, especially with a drop. ;) Anyone have a proposal for Team Instructables? They hold these things around the world, so it's not just US. I bet we could pick up on style points as well.From the official page:The first Red Bull Flugtag took place in Vienna, Austria, in 1991. Since then, more than 35 Flugtags have been held around the world -- from Ireland to San Francisco -- attracting up to 300,000 spectators. The record for the farthest flight-to-date currently stands at 195 feet set in 2000 at Flugtag Austria. The U.S. record stands at 155 feet set in Nashville, TN in 2007.Teams are judged on three criteria: distance, creativity and showmanship. What constitutes a craft is purely up to the imagination of the participating teams. Past Red Bull Flugtag entries have included a pregnant cow, a diaper-delivering stork, a pimped-out Cadillac, a giant Oompa Loompa, and yes folks -- a lobster named Larry.

Topic by canida    |  last reply

Tank Implosion

Fun with air pressure and a vacuum.via Neatorama

Topic by fungus amungus    |  last reply

My Mousetrap Car

It's not perfect, it only goes 2-3 meters, and it's always failing in one way or another. Getting these things to work is harder than it looks.

Topic by Spl1nt3rC3ll    |  last reply

bicycle generator

Has anyone ever tried to build a generator that would fit inside the bottom bracket of a bicycle using the spindle thats attached to the cranks and pedals? seems it would work better than the ones that rub on the tires.

Topic by oldcrowrich    |  last reply

Ethanol-fueled Hummer - E85 H2

Do you think the people who designed this had some sort of irony-deflecting helmets?Hummer will offer E85-compatible flexfuel engines on both the H2 and H2 SUT starting for model year 2009, and by 2010, all Hummer models will be flexfuel-compatible. We'd have to put a few hundred miles on a test rig to say for certain, but based on our experiences with (a) Hummers and (b) ethanol rigs, we'd wager that the 2009 Hummer H2 E85 may well deliver the absolute worst fuel economy of any vehicle based off a light-duty truck chassis sold in the US in the last 20 years. Our guess: 11 mpg highway, 8 city. Going downhill. With a tailwind.As a special added bonus, E85 Hummer owners will be doing their part to jack up their monthly grocery bills---and everyone else's too--as increased demand for E85 has caused a serious disruption in a major component of America's food supply, which in turn has adversely affected the price of meat and dairy products, sodas and sweets, breads and breakfast cereals, baby formula, jellies and jams, salad dressings, and yes, even our beloved corn dogs. Now you've really ticked us off! But hey, it's clean and it's green. When you put it that way, $7.99 for a bag of tortilla chips doesn't sound so bad after all, now does it?via Fourwheeler

Topic by ewilhelm    |  last reply

I need your help you guys!

Hey i had a cool idea about a shoe. Ok so here is my problem... i longboard and skateboard alot long distances, and my ankle and foot get tired from constant pushing down on the ground and then back up again. So i came up with a neat idea, what if i made a shoe or boot that i stick on my foot just when i am "pumping" or riding long distances and then it could come off. it would somehow have to have a spring system so that when i push down and then back it would coil up and then when i puched forward it would release hopefully cutting down the load on my ankle by a certain percent. any ideas? i have drawn a rough sketch...

Topic by TeacherOfTheWays    |  last reply

Elementeo Chemistry Card Game

14-year-old Anshul Samar has created his own science-based fantasy card combat game Elementeo. Check out the interview with him below.Elementeo is a strategic battle game where you use your elements across the battlefield in reducing opponent's electrons to zero. You do that by harnessing the strength and moving properties of the elements and compounds, and by using their reactionary powers. For example, Oxygen can rust any neighboring metal or Copper Conductor can shock any metals and send them back to the deck. via Wired's Geekdad

Topic by ewilhelm    |  last reply

Jeep Waterfall

If you haven't already seen the Jeep Waterfall, I advise that you check it out since it is exceedingly awesome. While you're at it, you may as well check out Autobiography of a Jeep. It's a classic.

Topic by randofo    |  last reply

Killerjackalope's social experiment results

Well I've been conducting a secret social experiment using shopping bags and the environmental topics everywhere as a media for this to happen. Basically my plan was to see if I could affect the decision of whether or not to take a bag when it's not completely necessary, to change the course of decision I used different phrases and tried to get a more accurate measure by choosing the same people that come in for milk or bread each day.The phrases are:'Would you like a bag?''Do you want a bag''Do you need a bag?''Wee bag there, mate?'Bag?'The results were really quite interesting, the one putting emphasis on need (very subtlety) reduced bag takings by over half in a day, whereas 'Wee bag there, mate?' produced a very high bag taking day because it detracts from the bags impact as an object. The other things I found was that it's actually possible to control some customers bag taking completely, there's a customer that comes in every day to get milk and I have managed to control his bag taking with about a 95% success rate, so shopkeepers unite and we can eradicate unnecessary bag taking, thereby reducing the majority of plastic bags that end up in the street and ocean, landfills are another story, thankfully my stores bags are fully biodegradable...What do you make of all this, and is it possibly a bit much power to give to a shop worker...On another note I have curtailed the efforts of one customer I know as the bag thief, he used to take five or six for various uses, through gentle shame jibing he's now down to one.

Topic by killerjackalope    |  last reply

Embarrassing Moments in Engineering

Mental Floss compiles four great examples of not-so-great engineering feats and one dramatic fix. The Tacoma Narrows Bridge makes an appearance, of course, as well as three other detailed examples to learn from. Mental Floss articlevia Neatorama

Topic by fungus amungus    |  last reply

Making a bug collectors helm.

Does anyone know of some instructions to make a leather type cap with magnification glass or strange levers protruding out of it? I'd like to make something "weird-scientist"-like for my entomologist friend, Thanks! edited to spell "bug guy" correctly

Topic by Oakherder    |  last reply

I dream of cheesy

I have just learned that people believe that eating cheese before bed will give you nightmares. I have also just learned that scientists have proven this not true. In fact, earing cheese before bed will improve your sleep and depending on the type of cheese that you have eaten, will depend on the types of dreams that you have. Now, I wonder how all that Cheez Whiz that Tetranitrate has been eating is affecting his sleep. You can't make this stuff up.

Topic by randofo    |  last reply

What Littlechef should really be worrying about.

Each year, Dihydrogen Monoxide is a known causative component in many thousands of deaths and is a major contributor to millions upon millions of dollars in damage to property and the environment. Some of the known perils of Dihydrogen Monoxide are:Death due to accidental inhalation of DHMO, even in small quantities.Prolonged exposure to solid DHMO causes severe tissue damage.Excessive ingestion produces a number of unpleasant though not typically life-threatening side-effects.DHMO is a major component of acid rain.Gaseous DHMO can cause severe burns.Contributes to soil erosion.Leads to corrosion and oxidation of many metals.Contamination of electrical systems often causes short-circuits.Exposure decreases effectiveness of automobile brakes.Found in biopsies of pre-cancerous tumors and lesions.Given to vicious dogs involved in recent deadly attacks.Often associated with killer cyclones in the U.S. Midwest and elsewhere, and in hurricanes including deadly storms in Florida, New Orleans and other areas of the southeastern U.S.Thermal variations in DHMO are a suspected contributor to the El Nino weather effect.Those are from an American study. I personally have seen quite a horrible crash after liquid DHMO was sprayed across a road, and DHMO was found in the analysis of the first stones removed from #2 son's kidneys.Proper statistics are hard to dig up, but I have found that DHMO was a direct cause of death in 3842 cases in the USA in 2002. 8.5% of them were children under the age of one.Numbers are harder to find in the UK, but around 500 deaths occur every year following contact with DHMO.(A drop of 4% in DHMO deaths in 2001 was attributed to fewer people visiting rural areas thanks to the foot-and-mouth outbreak, indicating a prevalence of DHMO contamination in England's green spaces.)Rather than scaremongering, you should be warning your friends about a very real hazard in their everyday lives.

Topic by Kiteman    |  last reply

attaching grind plates on aggressive skates

I havent ridden my aggressive skates for a while so i cant remember which side to attach my grind plates, (for some reason i took them off when i stopped usin them.) can someone help.

Topic by XI3    |  last reply

Logo Carved onto human hair

Thought I'd share thisBoing Boing Gadgets' Joel Johnson was at McMaster University yesterday where he met a researcher who used a focus ion beam microscope to carve his school's logo on a human hairI find it amazing how well it came out. If we can do this now, just Imagine what well be able to do in the future! Advertisement spaces in hair?!!!

Topic by Keith-Kid    |  last reply

Rope Faling

What would happen if you put a rope around the world and tied one end to the front of a house and one to the back of the house the held on to it and cut it on the other side (not the on your holding on to)

Topic by Slayer7    |  last reply


HI, I'm looking for cool science things to make EG: wind turbine that produces electricity.

Topic by Slayer7    |  last reply

Paleontologist prints fossils in 3D

French palaeontologist Paul Tafforeau has been using 3D lithography to make microscopic fossils, hidden in opaque blocks of amber, vsible for detailed study.Using intense light from a synchrotron (a kind of particle accelerator), he illuminates the amber, revealing, so far, over 350 specimens of trapped insects in 2kg amber. Some of the species are new to science.3D images are built up with micro-tomography, and these digital images are used to recreate millimetre-scale insects as plastic models at a scale that allows easy handling and visual study without needing microscopes.BBC Story (included iPlayer video, which may not be viewable outside UK)

Topic by Kiteman    |  last reply

Without Hot Air: Mackay's new Book on Global Warming

My friend told me about a new book by David Mackay. I've added screenshots of two of the really nice graphs he put together in his book. Says my friend:Forwarded Message:David Mackay, Cambridge U Physics Professor and a flat-out rockstar inthe field of statistical inference, has written a book on SustainableEnergy, which he is (as usual) giving away for free on his website.'s also a few slide decks for the overview: a blog:'m not much through it yet, but the gist seems to be putting realnumbers on the size of the energy problem, much as Saul Griffith hasbeen doing. It's written in his usual style, which is to say it readslike common sense you feel you should have known all along.

Topic by nagutron    |  last reply

Smaller taser setup

Is it possible for a novice tinkerer like me to use just the capacitor from a disposable camera to make a taser, wiring the battery in seperately instead of using all the plastic?

Topic by grantdevine    |  last reply

Explore the Human Body with an Online, 3-D Interactive Tool

Argosy's Visible Body is the most comprehensive human anatomy visualization tool available today.This entirely Web-delivered application offers an unparalleled understanding of human anatomy.The Visible Body includes 3D models of over 1,700 anatomical structures, including all major organsand systems of the human body.Link via Pop Sci

Topic by Tetranitrate    |  last reply

Battery Power in a Taser

Hey, I'm making a 'Glove' Taser using a disposable camera and I wanted to know a few things which most people who read this will laugh at. Firstly, I wanted to put a stronger battery into it and wanted to know what the best battery to use was, keeping in mind that I wanted it to be hidden so I can't use C or D batteries or anything like that. And secondly whether by soldering more wire strands to my contact points (the hurty bits) whether it would carry a greater charge? ie, if 5 strands of copper wire carries 'X' charge then maybe 15 strands would carry '3X' charge. Any help here would be a huge bonus and when I make my Instructable on my Glove Taser I'll give credit to anyone who tried to help me XD

Topic by grantdevine    |  last reply

Brendan Walker - Professional Thriller

The Howtoons Blog has linked to a really fascinating interview with Brendan Walker, a man that makes thrill rides for a living. He apparently got his start by discussing home-made fireworks on a job interview with British Aerospace. So, there is hope for some of you yet still!

Topic by randofo  

GEN H-4 Mini Personal Helicopter

The GEN H-4 personal helicopter weighs 70 kg, carries 220 kg total, has 40 hp of 2-stroke power, counter-rotating props, and costs $35 K. Check out what it takes to put together:, get a flying motorcycle from Butterfly Gyroplane:

Topic by ewilhelm    |  last reply

Making a car purr- roar

Well this one is not that hard you just need to take off the muffler and of course a nice engine helps. I suggest if anyone wants to win this that has basic knowledge of cars and has acces to a torch-welder and saw should do this instructable. Any other suggestions for the person who decide to take this task are what this post is for. Enjoy Duck-lemon

Topic by duck-lemon    |  last reply

Cold Weather Bike Wind Deflector

So I've taken an indirect pledge not to commute to school VIA car - by not buying a parking decal... Since school started, I've commuted, by bike, nearly 400 miles. But now it's starting to get cooler. I really don't like riding in cold weather. I typically wake up cold, get ready (still feeling cold) and getting on a bike when it's cold out is pretty uncomfortable.... So, for my next ugly bike abomination accessory.... My first wind deflector fairing prototype. I made a model in SketchUp (this was my "learn to use SketchUp" project), then from that make a development drawing (3D shape to 2D cutout) and cut that out of some scrap cardboard (I've got quite a bit that I rescued). Yes, there are flaws in this design - it's my first attempt :p As of now, I need to figure out how to mount this thing. I currently have some surplus 1/4" threaded rod at my disposal, I'm going to grab some and see where it takes me :p Comments?

Topic by trebuchet03    |  last reply

Making a car purr- roar

Well this one is not that hard you just need to take off the muffler and of course a nice engine helps. I suggest if anyone wants to win this that has basic knowledge of cars and has acces to a torch-welder and saw should do this instructable. Any other suggestions for the person who decide to take this task are what this post is for. Enjoy Duck-lemon

Topic by duck-lemon  

AC motor power supply

I have an old Dayton electric motor I pulled out of a lab blower. (I have no idea how old it is, I pulled it out of my grandpa's bottomless basement.) It looks like it still works, but I found it with no wires or anything attached to the terminals. (All of the internal connections look good, however.) So, here's the tricky bit, how do I run power to it? I copied everything off of the label on the motor, and I'll post it on the end. I've got very near to 0$ in the project bank, so the cheapest I can possibly do this the better. I don't need anything nearly as sophisticated as speed control, or anything like that. Here's the info from the label: model: 5K261 HP: 1/3 RPM: 1725 V:`115 A: 5.4 Hz: 60 Time Rating: Cont. Temp. Rise: 48C PH: 1 Frame: 56 Brgs: Sleeve Code: H S.F: 1.35 S.F.A: 6.0 Amb: 40C No.: S60CXCDY-4065 Insul: Class: A Thermally Protected: AUTO I'm not quite sure what I'm going to do with it yet, that depends largely on how well it works.

Topic by Helioskannon    |  last reply

Multi-Source power?

Hello all, i'm thinking on a very easy way to support more than 1 power source for my electronic circuits.Below you can see the schematic. It's very basic. Each source have a rectifier diode to disallow inverse currents for each one.When both sources have the same output, both diodes will work and the output is Vin - 0.7When one of them is bigger than the other (the case on the schematic), diode on smaller source will open circuit, and the bigger is the one to be used. The output will be 7-0.7 = 6.3V.The problem i found is when there is little difference, this is less than 0.7V.This way both diodes will work but there is a difference on voltage between the two sources.Do you think that having a small resistance like 10Ohm and high dissipation in one line will solve this?Do you think this design is valid?thanks for the help in advance.

Topic by Tigrezno  

Steampunk Scooter

Oh, to have a steampunk scooter that actually shoots steam out the back as you ride. This makes me want to get a cheap old scooter and rip it apart to create something new. Linkvia BoingBoing

Topic by fungus amungus    |  last reply

Minimizing Hills on a Bike

Things are crazy out there, with gas prices spiking, so I've been biking a lot more. Grocery runs, going to work, etc. I don't go out much any more, though, especially with people in a lot of neighborhoods getting "grabby." Forget riding around with a nice-looking laptop bag. In any case, a practical question: what's the best way to find the best route on a bike so that you don't tangle with too many hills? It's often hard to figure out here in San Francisco, especially if I'm riding my fixie or lugging a bunch of stuff in a trailer.

Topic by nagutron    |  last reply

Electoplating wood. CHEMISTRY QUESTIONS!

Hello guys, Thanks alot for reading. I don't know much about chemistry outside of my one high school class. We electroplated a penny. I have a 1.5ish square-foot piece of wood, and i am wanting to CHROME IT.... chrome paint kits cost hundreds of dollars, and i've before seen chrome-plated wood.. and i want to replicate the results. [img][/img]I'm looking for a cost effective alternative to expensive chrome kits (+300 dollars for a pint)In theory.... my method would involve somehow plating the guitar with some sort of metallic based paint, then submerging it in a chrome bath. [b]IS THIS POSSIBLE??[/b]Is there a metal chemical that can somehow be applied evenly to the entire surface of the wood? (i.e. paint?)What, and how much of the specific chemicals do i need, and where can i find them?I really want this to be mirrored. Thanks so much for your responses to my problem:P

Topic by punx777  

Popular Mechanics 2008 DIY Rally

Submissions for the 2008 Popular Mechanics DIY Rally close on April 4, 2008. If you've got something cool, be sure to enter it (and post an Instructable!). Here's the official announcement:Popular Mechanics' race for the best DIY projects of 2008 is on! Can you top a pedal-powered air gun? A self-tending barbecue? A motorcycle that rides on water? Whatever you've been hammering away on in your garage or basement, we want to see it. If it qualifies for the magazine's annual DIY Rally, you and your project will be featured in an upcoming issue. Use this online form to enter, but be sure to do it soon. Submissions must be received by April 4, 2008.Submission formAstute readers will note that the winning entry, shown in front of the loading dock at my old hangout, MITERS, was submitted by Damon, who now works for a Squid Labs spin-out company.

Topic by ewilhelm  

Instructable not showing up.

Hey, I published an instructable yesterday about 1 o'clock central time about a DIY CO2 reactor, and it still hasn't shown up under the "recent" tab. Is this normal? Is there someone I need to contact about this problem?

Topic by Sgt.Waffles    |  last reply

I have just added a new group! We would love new members

Greetings, I have just added a group on instructables. we welcome all with any kind of instructable (except for knitting and origami) it would be awesome to have you join today

Topic by Pumpkin$  


I'm building a kickbike out of two mountain bikes. The goal is to do it without a welding kit. I'll have pics up soon. cheers, Dick Lawless

Topic by RichardKL    |  last reply

Disabling daytime running lights on '99 Sienna?

Tried pulling the fuse (works but also cuts HLs), don't want to short E-brake limit switch (although that will cheat the circuit). I'm thinking of cutting the "DRL resistor", will that work?

Topic by Razortape    |  last reply

hovercraft parts

Me and my bro along with some other people are building a hovercraft made for 7 and will be used as an airsoft soldier carrier how do I make a steering device and how does the skirt work p.s we havnt started yet

Topic by grayecastle  

Voltages for 7AH, SLA batteries

So I've read all on the web about the voltages of a lead acid battery, and according to sites like This One the battery should be full at 12.69v or so. The only thing is I'm getting 13.02v on one SLA, and 13.08v on another. One of the batteries is brand new, and the other is out of a UPS. Are these batteries badly overcharged, or am I just really ignorant and can't find a simple site listing SLA voltages :) The batteries were not connected to anything for about 12 hours before I took the readings, and I have tested the multimeter I used, and it is accurate.If it helps, the battery says:Constant voltage charge(25C)- Cycle use: 14.5-14.9V- Standby use: 13.6-13.8V- Initial current: 2.1AAny advice / help would be greatly appreciated!PS) The main project is powering a computer with these batteries. I've done that so far and it draws only around 1.8A, so hopefully it could last for quite long! (~5 hours or so)

Topic by cb22    |  last reply


So, my circuits professor described electrolytic capacitors today, and said that reverse-biasing them could cause a catastrophic, eye-popping explosion. All that in a little metal can? I had to try it! Here's what it takes:

Topic by stasterisk    |  last reply

What metal do people use to throw up sparks with their lowriders?

I've always thought that it was magnesium, but I've heard that titanium is used. It seems titanium would be mucho-expensive for what it does. Does anyone know anything about it? If I find anything with a reasonable price, I may make a project about it. Thanks, Bran.

Topic by Bran    |  last reply

Real time plotting in Matlab

Hey ppl need some help, im working on a temperature controller that is based on 89c52 microcontroller, the sensor data is conv to digital by an adc0804 & the data is sent to the pc via the rs232 port, i need to plot a temp graph using matlab in real time, ive read that the hold function could be used but i havent had any success so far........ need help with the matlab code, the rest is fine... the baud rate is 9600

Topic by vedvern