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I need help with my arduino code, the error code is "stray #" . located at #define DO_NEXT 4

1.//iOS switch control example 2.//Simple version 3.#define MY_DEBUG 1 4.#include "BluefruitRoutines.h" 5. 6.//Pin numbers for switches 7.#define PREVIOUS_SWITCH A0 8.#define SELECT_SWITCH A1 9.#define NEXT_SWITCH A2 10. 11.//Actions 12.#define DO_PREVIOUS 1 13.#define DO_SELECT   2 14.#define DO_NEXT     4 15. 16.uint8_t readSwitches(void) { 17.  return (~(digitalRead(PREVIOUS_SWITCH)*DO_PREVIOUS 18.      + digitalRead(SELECT_SWITCH)*DO_SELECT 19.      + digitalRead (NEXT_SWITCH)*DO_NEXT) 20.     ) & (DO_PREVIOUS+ DO_SELECT+ DO_NEXT); 21.} 22. 23.//Translate character to keyboard keycode and transmit 24.void pressKeyCode (uint8_t c) { 25.  ble.print(F("AT+BLEKEYBOARDCODE=00-00-")); 26.  uint8_t Code=c-'a'+4; 27.  if (Code<0x10)ble.print("0"); 28.  ble.print(Code,HEX); 29.  ble.println(F("-00-00-00-00")); 30.  MESSAGE(F("Pressed.")); 31.  delay(100);//de-bounce 32.  while (readSwitches()) { //wait for button to be released 33.    /*do nothing*/ 34.  }; 35.  ble.println(F("AT+BLEKEYBOARDCODE=00-00")); 36.  MESSAGE(F("Released")); 37.} 38. 39.void setup() { 40.  if(MY_DEBUG) 41.  while (! Serial) {}; delay (500); 42.  Serial.begin(9600); Serial.println("Debug output"); 43.endif 44.  pinMode(SELECT_SWITCH, INPUT_PULLUP); 45.  pinMode(NEXT_SWITCH, INPUT_PULLUP); 46.  pinMode(PREVIOUS_SWITCH, INPUT_PULLUP); 47.  initializeBluefruit(); 48.} 49. 50.void loop() { 51.  uint8_t i=readSwitches(); 52.  switch (i) { 53.    case DO_PREVIOUS: pressKeyCode('p'); break; 54.    case DO_SELECT:   pressKeyCode('s'); break; 55.    case DO_NEXT:     pressKeyCode('n'); break; 56.  } 57.} void setup() {   // put your setup code here, to run once: } void loop() {   // put your main code here, to run repeatedly: }

Question by JacLir00179    |  last reply


Stray Cats Strut

Sad to say, a homeowner in the neighborhood takes no care of her cats and, of course, we had a bumper crop of strays for a while until nature and cars took care of most of them.  Two or three full-grown cats from the original litters are now quite healthy and roam our neighborhood freely.  As I have two indoor/outdoor cats, the "Wilds" have decided to take our yard as their own and you all know how cats mark their territory.  Every corner of our house, planters, and bbq has been sprayed as the battle for territory continues.  They're quite bold; I ran into one in our garage!  I'd like an effective, safe, non-painful (and entertaining, if possible) way to discourage them from coming into our yard and/or what I can spray over their spray to  nullify their scent.  (Baking soda and water mix, etc.)  I'm not home during the day to "catch" them in the act, I need something long-acting.  Thanks!  

Topic by Kevhead01    |  last reply


How do I keep a pack of stray dogs off my property?

My office has about 5 acres of land, not fenced in.  A neighbor across the street raises and breeds dogs.  When I arrive at work in the morning, I am greeted by anywhere from 5 to 10 dogs.  What can I do to run them away and keep them away?  We do not have a dog here, but there is a cat that came with the property that we feed. Thank you for any help.

Question by claramarguerite    |  last reply


Cats Ears with frostbite Starting to tear off. What should i do? Answered

We Took in a cat that was Hanging around our house and eating our dogs food. its Very cold out and i have no idea where this cat came from. He is a very Gentle Tom. He must have a had a home before. the tips of his ears. the top 3/8'' are tearing off. What should i do?

Question by unominame    |  last reply


Why does my LED lamp have AC voltage from case to ground and is it dangerous?

Here's the deal:  3-section under-counter LED light strip in an aluminum housing, with a 2 wire AC cable and plug for 220v. I found however, that when I set a voltmeter to AC and measure between the case and a ground (water faucet, natural gas line or the ground from an electrical socket) I get 74 volts with one unit and 89 with another. The seller first pointed out that a grounded cable should be used. I replied with pictures showing the unit is built to accept only two wire and comes with a two wire cord. Then they said using a sink as ground didn't truly represent ground and that the measurement was faulty and that the current is not dangerous regardless.  I took additional measurements using an electrical ground and the metal pipe from the natural gas line. Same result. However, I'm having trouble measuring current. I put the probe into the ten amp side, set the meter to the mA/A position and got nothing, although I did hear a buzzing sound emanating from the lamp housing--that can't be good. I then put the probe into the mA socket and tried again.  Same buzzing, no reading.  My questions: 1. What's wrong with my setup that I see no current measurement.  2. Is this a dangerous lamp? I took the one near the sink down. The other one is not within reach of an accidental grounding, so it is up until I'm ready to return both units. -Bob

Topic by bobcov    |  last reply



Has Instructables strayed too far from its origins?

Hi  So I posted a comment here today: https://www.instructables.com/id/Building-a-3D-Printer-Under-299/?ALLSTEPS see- mjreller (or see the attached pic) I have been a big fan of the site since 2008 and things have changed. I am aware that many 'bootstrap' projects are available and they probably make up the majority of the total. BUT, so many, like the one linked above have almost no information about how to actually build the item. Does this make it a bad 'ible?  In my mind, heck yes it does. As the parent of a very bright young person I am constantly looking for projects to keep his (our) mind(s) expanding and growing. I look to this site frequently for ideas and it is becoming less and less useful. Clearly by voting/not voting I have a voice in what content succeeds here.  But I feel like I am in the vast minority especially when reading the other comments for the above linked 'ible.  Being impressed with what someone makes does not qualify it as a good Instructable. I make large allowances for tech shortcomings (I know not everyone has access to laser cutters, etc etc) but the INSTRUCTION should still be there. Am I naive to expect to have a clear idea how to make every project on this site? I don't think this is too much to ask when other commenters are complaining about Standard-Metric conversions. I welcome an open discussion, and consider this an opportunity to learn how to better use the site. thanks for your time, Matt

Topic by mjreller    |  last reply


How can I keep a stray cat out of my house?

I have a cat for whom I keep a window open, since she likes to go outside and come back in while we are gone at work.  Apparently, a neighbor's cat has come in our house to spray.  Does anyone have ideas on how I can keep the cat out?

Question by Enricommuter    |  last reply


Please put it back so people can locate it.

Answers link has strayed again in the last update. Please put it back so people can locate it.Richard Harris

Topic by rickharris    |  last reply


Cat chip logger

Could you modify the reader in a chip reading cat flap to log the details of the chips t hat pass through it rather than only let recognized chips open the flap? Chip reading cat flaps exist data logging is possible this I know, how to tie the two together is beyond me. Give me detailed instructions I could do it, but I'm more at home with working out how to wind the detector coil than what to do with it. The reason is this My sister has a problem, she is in danger of becoming a cat lady, or at least over run with strays or other peoples cats. Her current plan other than catching the visitors that are clearly street cats and delivering them to the local shelter, is setting a camera trap aimed at her cat flap and posting the visitor photos on the local area FB page with is this your lost cat under it.  couple of the poor conditioned strays she has managed to get to the shelter have been chipped it is  reasonable to assume that some of the others must be to, and they would be easier to catch possibly if their  owners were trying to do it. Even a simpler system that just connected chipped cat with photo, and there by identified which cats aren't chipped so presumably are true strays not just nominally owned would b of help those could then be targeted for capture and re homing first.

Topic by Stan1y    |  last reply


Release door on cat trap

I'm trying to trap a stray cat. The lenders didn't set it up right so now in my trying to figure it out I've got the trap door closed and can't figure out how to get it open. I know how to set it now...just need to open the door back up.HELP'

Topic by evalyng    |  last reply


I'd like to build a 3rd order low pass filter, cutoff ~40mhz, impedence at 28mhz of 50Ohms?

Hello All. I want to build a 3rd order low pass filter with a cutoff ~40mhz. I'd like to build this in a metal box seperated into two compartments with a pi filter in each. What components do I need? The input output impedence should be ~50 ohms at 28mhz. It stray capacitence a problem? Thanks?

Question by microcal    |  last reply


Do you guys think about this PCB design?

Here is revision 1 of my PCB. Also is a link to the schematic that is on the PCB design. https://easyeda.com/editor#id=BLztPfAkw|vUO60iAua It is a flyback driver based on the LM339 comparator. What is important is that the MOSFET is switched on and off very hard, very fast. audio is AC coupled into the second comparator which sets the PWM duty cycle. Is there any issue with stray inductance or other parasitic bad stuff in the PCB layout? Or any misteaks in the schematic?

Question by -max-    |  last reply


Should half inch thick, high-strenth chip board stop a .177 calibre pellet?

Should half inch thick high strenth chip board stop a .177 calibre pellet with a force of 8 ft pounds and travelling at 600ft a second? I have recently made a pellet trap it is a box with a high strenth chip board guard to stope stray pellets (as seen in the pic) the box is ok but i am worried about the guard. My air rifle is a BSA metour mk6?

Question by oscarthompson    |  last reply


Anti-Graffiti Coatings? Answered

Would any of the resident geniuses here at Instructables have any ideas for keeping graffiti off of my cedar fence? I live in a fairly rough neighborhood in a major urban center, and we exclusively have the bad type of graffiti-- crappy tags from juvenile delinquents delineating their turf. Any ideas on how to combat this problem with a DIY, cost-effective solution? I'm thinking it might just be something that most spraypaint won't stick to, or a surface that will destroy paint pens. Heat-sensing, motion-sensing automatic machine guns are not an option due to the rampant stray population ;) http://www.youtube.com/watch?v=TqIHlnfGKV0

Question by Nate Cougill    |  last reply


Any ideas to help teach a novice?

Currently I am working on a "lesson plan" to start teaching my brother about electronics. I have moderate skills, and would consider myself a jack-of-most-trades. What I am trying to say, is that I would like suggestions of instructables here that would be good to begin teaching a novice. The fields he wants to learn are computers, general electronics, and robotics. Though he is open minded, and would be willing to stray from those three things. Also, the maximum price per project would have to be AT or BELOW fifty (50) US dollars. Thank you for your time fellow makers. :)?

Question by Knuxz    |  last reply


How Was This Bench Upholstered?

I picked up this bench for $20 at Salvation Army. It's nothing special, seems to have been built relatively recently but it was in decent shape and I thought I could salvage it. The thing is I can't figure out how the seats were attached to the frame. When I bought it there was a border of old material that was stapled and glued to the top of the frame. I pulled out the staples and removed most of the material but you can see the stray threads where there's still some glue. There was also a plywood square in each recess in the frame but it seems a bit flimsy to support one's weight. There doesn't appear to be any diagonal supports for a seat to screw into like I've seen in most chairs. Any idea how this was originally constructed?? Thanks for your help! -Carl

Topic by carlbaron  


Genetic Circuit Design

Hackaday recently posted an article about genetic programming which was pretty cool (although technically it used a stochastic hill climbing algorithm....but who's counting?)The really cool thing was posted by acedio in the comments: genetic circuit designWhat these researchers have done is implemented genetic circuit design on an FPGA to create a circuit to light a light when someone says "go" into a microphone and turn it off when someone says "stop". Which is not really groundbreaking...but the way the genetic algorithm created the circuit is pretty amazing, it used what normal designers would consider unwanted characteristics of the circuit such as stray capacitance and inductance between components to "create" unavailable components out of logic gates, and because of this the researchers have no idea how it works!Computers can now design circuits in ways that would be damned near impossible for humans to do, how cool is that??!Deep thought here we come!

Topic by }{itch    |  last reply


Water-damaged PCB repair

So water leaked in to the General Electronic Module (GEM) on my pickup and now it's acting all funny. A/C runs when the ignition is off, randomly switching to 4L, airbag light chattering on and off, etc. I want to try and repair it. My intuition is that it just acts up when there's stray conductivity between traces/elements, so if I give it a good clean and keep it dry it should work like new.However, I noticed upon pulling it apart that there's some corrosion taking place. Can anyone suggest a good way to repair these traces/SMD resistors? I have a soldering iron but heavily oxidized things don't take solder well in my experience. Or should I just put some lacquer on it and not worry about it?Thanks!

Topic by RelaxedSoup    |  last reply


Kitty TV

Every year, winter comes to RI (as it should). Then every year my family makes a cardboard house for the outdoor cats (they started off as one stray cat a couple of years ago, but of course multiplied). The cardboard houses would be thrown out at the end of winter since they would become soggy (even though we covered them in plastic bags) and an eye sore on the porch. Last winter, one of our friends got a little overambitious and made a house that was way too big (we could have fit both of our Golden Retrievers inside with room to spare), so the cats didn't use it. Last month I reorganized my room and decided to get rid of the cabinet I had placed my TV in. I was gonna toss or burn it, but decided to convert it in to a place for the cats to live. The light located on top doesn't light up, but is instead connected to a flashlight connected to the interior of the cabinet which does light up when the push light is "clicked".

Topic by FrenchCrawler    |  last reply


How to set up a desired threshold voltage? Answered

Hi, What I need-A circuit which allows voltage which is greater than or equal to 3 volts "ONLY" to pass through and power a buzzer i.e,shouldn't allow theuzzer to be powered with a voltage lower than 3 volts. The details-I just finished a project which makes a buzzer sound at its final phase.But,yet another obstacle-A darlington pair first completes a circuit with a relay in it when the base of it receives positive current via a resistor.The relay is activated which in turn powers the buzzer with - ve 12 volts and this makes the buzzer sound as +ve 12 volts is already connected to the buzzer.But somehow the buzzer is making a feeble,rather irritating sound even before the relay is activated..and it is somehow getting powered with a stray 3 volt power due to a leakage,somewhere.I tried to trace the flaw but couldn't find it.What I have in mind is a circuit which will allow voltage greater than 3 volts only to pass through and power the buzzer,somewhat like the function of a zener diode.I kindly request your guidance in designing a circuit which has a threshold voltage of 3 volts and higher.(I'm thinking BC 547s,555 timers etc.).

Question by Adarsh_tronix    |  last reply


How can I connect a micro camera (a tiny spy one) to a small 4.5"-6.5" LCD screen to work as a sort of spy screen?

If you've played Modern Warfare 2, you know what the Heartbeat Sensor is. It's a small screen that is attached to the side of a firearm and is connected by visible wiring to some other unknown electronic parts. Really, though, I'm looking to recreate the screen concept as a camera + viewing screen that will work in low-light environments, specifically for paintball scenarios. I can make the outer shell and make sure it won't be ruined by a stray shot, but actually connecting the mini camera to the screen and having them work at all is an issue, and even more is having it work at night or in dark areas. I have basically no experience with electronics aside from plugging part A into slot A, part B into slot B, etc. I can work with computers easily, but physical wiring and such is a total blank card for me. I'd also like to know whether it'd require a specific screen to work. I'm completely open to suggestions, as long as the net weight of everything required doesn't exceed a few pounds, as the gun itself is already starting to lean towards the weight of actual firearms.

Question by Also The Game  


Terrible People

I recently was transferred by my job to another store.  I was quite excited, and looked forward to making a new start. But, only after five work days, I hear people are already talking behind my back, something I had been very careful to avoid. One person, who shares the same position as I, asked me to do something, but then after I left work, got me in trouble with my boss for the very thing she told me to do. Another thing is that I chose to tell two people at work about getting a new apartment (as to not be called in when I moved), but accidentally let slip something about my personal life.  A person who I trust told me that seven people had already come up to her to "dish the gossip" (her words, not mine), about my life.   What the bloody he** is going on here? I had started this new job with the idea that "work people are work people, and they will stay at a distance", and to be friendly, but not try to be friends with everyone.  Treat co-workers with respect, but leave it at that. I had not strayed one bit from this plan.  I did my job according correctly, and was very polite and friendly.  What could have went wrong?

Topic by Flintlock    |  last reply


Inventor Builds His Perfect Woman

From The Sun, 11 Dec 2008:SHE is the perfect wife, with the body of a Page 3 pin-up and housekeeping skills that put TV's Kim and Aggie to shame.Her name is Aiko, she can even read a map, and will never, ever, nag. Sounds too good to be true, doesn't she fellas? And she is.Aiko is actually a robot, a fantasy brought to life by inventor Le Trung. Devoted Aiko --- "in her 20s" --- has a stunning 32-23-33 figure, pretty face and shiny hair.She is always happy to clean the house for "husband" Le, help with his accounts or get him a drink.Computer ace Le, 33, from Ontario, Canada, has spent two years and £14,000 building his dream girl.He had planned to make an android to care for the elderly.But his project "inspired by sci-fi robots like Star Wars's C3PO " strayed off-course. [ ... ]He said: "Aiko doesn't need holidays, food or rest, and will work almost 24 hours a day. She is the perfect woman."Aiko sparks mixed reactions in public.Le said: "Women usually try to talk to her. But men always want to touch her, and if they do it the wrong way she slaps them."Read the whole article, with a video clip and pictures, at http://www.thesun.co.uk/sol/homepage/news/article2023392.ece

Topic by kelseymh    |  last reply


Can a cracked guitar neck be fixed?

Hi, I finally signed to Instructables. :) My colleague is a big DIY guy and that's how I came across Instructables. Today, while searching for something I came across homemade recipes for musical instruments and that really hooked me on. Especially the one on turning an 6-string acoustic to bass acc. :) I had tried learning the guitar but didn't want to spend too much on the instrument, so I bought a second hand one from a garage sale (proceeds were for the city's stray dogs - so for me it was a bit of a win-win...almost :) ) What I realised much later is that: 1) The wood under two of the tuners (on the under/ventral side of the guitar) has splinters 2) One of these tuners has lost a fastening screw because the hole in the wood has widened and splintered a bit 3) the base of neck, just before the curve block that connects to the box, has a 1-2mm crack running across it (horizontally) Question is, can these issues be fixed so that a beginner like myself or someone who really doesnt have the money to own a guitar but wants to learn can still use it for some time? I never found the time to go to a music shop to have it checked. I also feel they will probably turn me away because they are more interested in selling guitars than fixing them. I really dont want to just throw it away. Second hand it may be, it just doesn't feel right... Your inputs would be greatly appreciated. Thanks! P.S.: Am at work right now but I will try and post images of the guitar as soon as I can. I had taken photographs of it a looong time ago. As a result, tuning goes off every now and again. On a colder day, tension increases and the crack widens. Update: Terribly sorry for the delay in uploading the pictures. I had a set that I had taken a year or so ago but I seem to have deleted them. Just got some time off work, here are the pictures. The crack, which I had earlier described as horizontal, is in fact, vertical. So much for my memory...

Topic by aristarkhos    |  last reply


Throwies reimagined - Really I did tried :) :| :/

Seeing other forms of making interactive throwies, eg using microchips impresses me.However i think it is important that we try parts of the B.E.A.M philosophyhttp://en.wikipedia.org/wiki/BEAM_roboticsNamely keeping things simple, and avoiding the use of microprocessor.The component of a interactive throwie is that it has1. Power storage2. Trigger3. Circuit4. LED5. (optional) Power collection of radiant energy.I like to see more suggestion on ways we can address each issues.But to kick start the issue, can you see if my idea is feasible.essentially for my prototype not-yet throwie, I used a circuit from http://unconventional-airsoft.com/2003/11/16/momentary-fan-switch/#more-21to create a throwie that on sensing motion, doesn't flicker but turns on for a while.By ensuring that i use few and simple componants, i hope to keep cost per throwing down.Unfortunately my problem is that using a resistor to keep the capacitor from draining too fast from the base, actually decreases the voltage drop to an unacceptable level at the led.On my end it is unsolvable for the moment. Maybe you can work out how to make a cheap throwie, that can still do these functions or more.Any ideas how to solve this?Other Ideas for throwies1.Open and attach a switch to a barometer, to have a air presser passive trigger.2. A leave shaped pad with two conductors that do not touch, to act as rain sensors. (Resistance increase when leaf dries)3. Is sensitive to infrared radiation from side, so that the throwie is trigger-able by other activated throwies. (As well infrared devices)4. Has a short loop of coil to recharged capacitors, by outside induction.5. If activated rarely, uses a tiny single solar cell to charge capacitor.6. Has a hook to be easily collected for recycling. (Using a simple loop of wire on a pole [Like a dog catcher pole] )7. A single thermistors in series with led.8. A tricolour LED, and a Two light resistor. One LDR acts to sense if it is day an night, if night a low power light is activated. Only when an object strays near, and reflect light into another LDR, does the throwie get triggered at all.9. A throwie triggered by vibration.10. A throwie that responds to radio waves.

Topic by akimbo m    |  last reply


I have been working on a robot for a while. Can someone help me my code?

I built a robot with an arduino and a thunder tumbler rc. Can someone help me with my code? I will post a video on youtube of what it does. I want the tumbler to drive straight and when the bump switch gets hit it will back up and turn left or right(can remember) and then drive straight again. Here is the code. There might be a few stray bits from a ping ultrasonic sensor in there as well. I dont want that but i didnt see anything left. int switchPin= 2; // Right bump switch on pin 2 int swval; int ledPin = 13; // LED connected to digital pin 13 int motorpinright = 11; // pin for left motor reverse int motorpinleft = 9; // pin for left motor forward int motorpinrevright = 3; // pin for right motor reverse int motorpinrevleft = 10; // pin for right motor forward void setup() { pinMode(switchPin, INPUT); // Sets the digital pin as input pinMode(ledPin, OUTPUT); // Sets the digital pin as output pinMode(motorpinright, OUTPUT); // Motor drives----------- pinMode(motorpinleft, OUTPUT); //------------------------ pinMode(motorpinrevright, OUTPUT); //------------------------ pinMode(motorpinrevleft, OUTPUT); //------------------------ } void loop() { delay(100); analogWrite(motorpinleft, 255); //100% speed analogWrite(motorpinright, 255); //100% speed0 analogWrite(motorpinleft, 0); //stop left motor analogWrite(motorpinright, 0); //stop right motor analogWrite(motorpinrevright, 0); // stop right rev motor analogWrite(motorpinrevleft, 0); // stop left rev motor analogWrite(motorpinrevright, 255); //100% speed analogWrite(motorpinleft, 255); //100% speed delay(380); //380 milliseconds analogWrite(motorpinrevright, 0); // off analogWrite(motorpinleft, 0); // off digitalWrite(switchPin, HIGH); // Sets the pin to high swval = digitalRead(switchPin); // Read input value and store it if (swval == LOW) { analogWrite(motorpinleft, 0); //stop left motor analogWrite(motorpinright, 0); //stop right motor analogWrite(motorpinrevleft, 0); // stop left rev motor analogWrite(motorpinrevright, 0); // stop right rev motor analogWrite(motorpinrevleft, 255); //100% speed analogWrite(motorpinrevright, 255); //100% speed delay(800); //800 milliseconds analogWrite(motorpinrevleft, 0); // off analogWrite(motorpinrevright, 0); // off analogWrite(motorpinrevright, 255); //100% reverse speed analogWrite(motorpinleft, 255); //100% forward speed delay(700); //700 milliseconds analogWrite(motorpinrevright, 0); // off analogWrite(motorpinleft, 0); // off delay(50); //50 milliseconds } /*------------------------------------------------ */ }  

Question by TOCO    |  last reply


A Hybrid of Coil and Rail gun

So I said i'd throw this up in the comments section on Youtube not too long ago, and I don't like it when something easy and free doesn't happen. This is some ideas and observations that have to do with coil guns (mostly). I'm in the process of finishing up several projects, so my resources are kinda spread out. I should have a prototyped coil gun finished in 2-3 weeks though, so if this doesn't clear things up, hopefully that video will. I should point out, I am a chemist with expertise in biochemistry, not electrical engineering. Basically my idea is to combine a railgun and a coil gun for the expressed purpose of avoiding the pitfalls that a pure coilgun or a pure rail gun have. At present, none of the designs out there would be capable of competing with an actual gun. By mixing the two, i'm hoping to get something that might eventually be capable of doing so. So.. I've included a very poor drawing (I'm not an artist). The barebones circuit is sketched in the lower right hand corner. The gun barrel, which is a piece of aluminum tubing split into two pieces to sever as a rail system, is sketched in the upper left, and again in the middle figure to show how to integrate the coil and rail system. Looking at the circuit design, you can see that this starts off as a very basic capacitor-inductor circuit. The charge is purposefully allowed to trickle through the circuit until the coil reaches saturation and the capacitor(s) are charged. When the trigger is pushed, the inductor side of the circuit has to dump into the rail system to complete the full closed loop. Because of the ferromagnetic material (the brown stuff), the magnetic force persists for a while (that is to say, it has high reluctance). The ferromagnetic material does one other thing that is important here. It forces the middle of the coil to be far off center. The coil is pulling the projectile into the middle of the magnetic field, but that is not necessarily in the center of the winding. Adding ferrite, or other high reluctance material, towards the end of the barrel biases the field towards that end.  At the same time that the coil stops getting current, the rail system become active. This allows a charge to pass through the bullet/projectile, and, even though the majority of the force is going to be caused by the inductive coil, the rail system allows an eddy current to setup in the bullet. This does several things. First the bullet doesn't have to be iron, nickel, or cobalt. With a stray eddy current in the projectile, any conductive material will work. The advantage here is that once the current stops, the non-magnetic material stops being  to the magnetic field, preventing backwards acceleration of the projectile as it exits the barrel.  Second, Rail systems and coil systems are not often used because they are perpendicular to one another, but, this can be used to put spin on the projectile, in a similar manner to rifling in a barrel.  After the projectile is fired, the circuit is open, preventing excessive electrical discharge.  My circuit design is really badly drawn... =T if it needs more explanation please post up questions. 

Topic by Qcks    |  last reply


Rebuilding after the end has come to pass...

The year is 2054, the human race has endured its biggest and longest war ever leaving the last survivors to fend for them selfs in its wake. To make matters worse, a human designed diseasse has spread, thinning out the last survivors to less than 50.000 people all over the world who happen to be lucky enough to be ressistent to the dissease. There are no more governments, no more borders, no forms of modern society ''at all...'' except for your own rules and moral state of mind. Raw modern resources are almost all used up, maybe a few drops of oil here and there but not enough to be reliable for longterm use at all. City's have burn down to the ground, blasted into the sky or have bin left to decay and rust, there are simply not enough people arround to keep them running. U, yes U are one of the lucky ones to wake up one morning, having your loved ones by your side and you can see the sun come up! Your in a forrest, your car has run dry on fuel, but your alive and kicking! What would you do to survive, build a longterm home and grow out to become a safe haven for "all" who will find your place of refugee? These are the conditions you have that work for you: 1. You are not alone, you have the ones that are closest to you with you all the way. ( ideal situation huh? ) 2. The forrest you are in is huge, deu to the fact humankind has declined in such small numbers, nature hase taken back a lot of groundspace and it is booming! ( again, ideal! ) 3. You have a car, it is broken down, has no more fuel except some fumes, but you have it non the less... ( not so ideal, but still... ) 4. In the trunk you have a tiny solar panel, strong enough to fill your cars battery ( yup, one battery... but its 2054 so the poweroutput is more than enough to help you out in the first stages of building your new home. ) 5. In that same trunk you have sleeping gear for camping, a couple of pots and pans, some basic workingtools and a bundle of paracord, couple of hundred feet in length. ( you like paracord, o yes you dooo... ) 6. You see a chicken in the corner of your eye... your running condition happens to be excellent and so you take a sprint... There's your protein... ( eat the chicken, or keep it for later use? its yours now, so do what you want with it. ) This is whats working against you: 1. Guns are not a good option. All rounds off ammo that where ever made have bin used up. Even your trusty ol .45 lays in the back of your trunk not knowing its own purpose in life anymore... ( so sad... ) 2. City's? gone! Piles of rust and decay are the only things that are waiting for you over there. ( pluss, the bandits roaming the city are not the most happy bunch to cross with. ) 3. Fuel, nope, fumes, yes... ( not much going there... ) 4. Communication devices are out... ( you forgot to pack your radio, and now you have nothing to reach out with... or do you? ) 5. The spot your in is most beautifful, really, its the most beautifull patch of forrest you and all around you have ever seen!!! The gigantic mutated bears and stray wolfs think so too... ( Radition and the human designed diseasse worked toghether in the animal kingdom making these guys grow almost double there original size... see statement 1 for double sadness!!! ) Ok, taking the mutated bears and wolves aside, think outside the box. You have a car, thats something, and these bears and wolves will leave you allone as long as you let them do there thing. And if they dont get hungry enough to eat you ofcourse. ( Its a mutual agreement i guess. ) Im curious to see what you guys come up with, so be my guest and spit it out ;-)

Topic by AriedeB    |  last reply


Common written English errors.

I'll add to this as errors come to my attention. Perhaps this, or someone else's similar post, could be made a sticky - an always available point of consultation distinct from individual requests for, or offers of, help. I have a 2:1 Honours degree in Librarianship and Information Studies, and I also have a City and Guilds Certificate in teaching Adult Literacy. English is my native language. ------------ THERE, THEIR, THEY'RE THERE: Position: "The school is over there."; "There is the temple we have been looking for." Information: "There is a stray dog wandering around the house."; "There is a train leaving in 15 minutes." Slang: "He's not all there." (He is a bit stupid.) THEIR: Exclusively belonging to someone or something - no other meaning. "The coats are theirs." (the coats belong to them); "This is their car." (the car belongs to them); "Fords are OK, but their brakes can be spongy." (the brakes belonging to Ford cars can be spongy). THEY'RE: Short for "They are..." "Try some, they're very tasty."; "Surely they're not ending the gig without playing "Us and Them"?" A spellchecker may not locate words that are spelled correctly but used incorrectly. "My car is over their." is wrong usage, but the word, "their" is spelled correctly. A grammar checker may or may not locate such errors. (Microsoft Word 2007 combines spellcheck and grammar check, and does find such errors, offering the correct "there" as a replacement. -------------------- ITS, IT'S: ITS: Belonging to. "The pedal on the left is its clutch pedal." (the left pedal is the clutch belonging to the car - "its" = "the car's"); "Its mechanism is a bit fiddly, and poorly designed." (the mechanism belonging to something not explicitly mentioned is fiddly and poorly designed). IT'S: Short for "it is". "It's raining."; "It's cold."; "It's quite warm for November." -------------------- YOUR, YOU'RE YOUR: Ownership. "That is your car."; "Your instructions are misleading."; "What was your day like?" YOU'RE: Short for "you are". "You're wrong about that, it's the other way around."; "You're pulling my leg, that's not even remotely possible." -------------------- THAN, THEN THAN: Comparative. "My car is better than yours."; "I feel better than I did yesterday."; "I would sooner be there than sitting here doing nothing." THEN: Sequence; "Add an egg, then whisk until fluffy."; "Go to the corner, then turn right." Also colloquially, "Then again, I might decide to fly, after all."; "What's all this about, then?" Usual error is "then" instead of "than". I've never seen it the other around. Becoming more common, and it has appeared as the only error in a good few Instructables. -------------------- SHOULD OF, COULD OF, WOULD OF, etc. All simply wrong. They do not exist in English, and are misheard shortenings of "should have" (should've (sounds like "should of")), "could have" (could've), "would have" (would've), etc. -------------------- TO, TOO, TOO TO: "It's time to go to school."; "Let's go to the cinema."; Hi ho, hi ho, it's off to work we go." TOO Also\as well. "I'm coming, too."; "I, too, use Linux Mint." TOO Excessive. "That's far too much for me!", "You go, if you like, but I think it's too expensive to get in." -------------------- THE APOSTROPHE The apostrophe does a few unconnected things. Indicates ownership: "The dog's bowl." (The bowl belonging to the dog.); "That pink collar is the cat's." (That pink collar belongs to the cat.); "Microsoft's Windows 7 is the best Operating System." (The Operating System belonging to Microsoft.) Indicates missing letters: "They're" (They are); "Can't" (cannot); "I'bles" (Instructables). To indicate ownership of a plural that ends in "s", or pronoun (name) just add the apostrophe at the end without any additional "s": "The ship's (a single ship) colours have been changed to red and grey." "The ships' (all the ships in the fleet) colours have been changed to red and grey." (Else you would get "ships's"; which Golem might say.) "Mr Jones' car is a Skoda." Not Jones's, although, it seems, it's a matter of preference. My preference is brevity.   BUT an apostrophe NEVER EVER makes a plural, "banana's" is wrong, it's just "bananas"; "goat's" is wrong, it's just "goats". Used this way it could indicate ownership, "The banana's skin is yellow." (The skin belonging to the banana.) Detailed examination at; http://www.eng-lang.co.uk/apostrophe_rules.htm -------------------- DIFFERENT. You will often see "different" used with "than", or "from", or "to". The preference is "from", because one says "it differs from", not "it differs than", or "it differs to". Detailed discussion at; http://grammarist.com/usage/different/ -------------------- "REPLACED WITH", or "REPLACED BY". Both can be correct. See MilkyBarKid's post in a thread at; http://forum.wordreference.com/threads/replaced-with-or-replaced-by.1985166/ -------------------- MISLED, MISLEAD Both are correct, but have different uses. "He was misled by the sneaky salesman." "The sneaky salesman tried to mislead him." -------------------- LESS, FEWER Fewer is used when individual things or people are being referred to; cars, telephones, knives, people, churches. Less is used when things being referred to cannot be counted or don't have plurals; traffic, communication, cutlery, worship. Fewer cars mean less traffic. -------------------- If you have any particular points or questions, I'll be glad to research and post.

Topic by FirstSpear    |  last reply


My Current 100 Favourite Songs

Inspired by Viccie's topic, I made my own. It took about an hour. 1. Riff Raff - AC/DC 2. Paradise City - Guns 'n' Roses 3. It's A Long Way To The Top (If You Wanna Rock 'n' Roll) - AC/DC 4. November Rain - Guns 'n' Roses 5. Sweet Child 'o' Mine - Guns 'n' Roses 5.5. American Idiot - Green Day 6. Let's Get Rocked - Def Leppard 7. Dirty Deeds Done Dirt Cheap - AC/DC 8. You Shook Me All Night Long - AC/DC 9. Dream On - Aerosmith 10. T.N.T - AC/DC 11. ELMO'S SONG! 12. Back In Black - AC/DC 13. Rocker - AC/DC 14. Thunderstruck - AC/DC 15. Shot Down In Flames - AC/DC 15.5 The Wall (Pt II) - Pink Floyd 16. Whole Lotta Love - Led Zeppelin 17. Fallen Leaves - Billy Tlent 18. Red Flag - Billy Talent 19. Surfing With The Alien - Joe Satriani 20. Devil Gate Drive - Suzi Quattro 20.5 My Apocolypse - Metallica 21. Beatin' Around The Bush - AC/DC 22. Welcome To The Jungle - Guns 'n' Roses 23. Moonshine - Savage ft Akon 24. I Believe In A Thing Called Love - The Darkness 24.5. One - Metallica 25. The Furor - AC/DC 26. Love At First Feel - AC/DC 27. Let There Be Rock - AC/DC 27.5. Whole Lotta Rosie - AC/DC 28. Layla - Eric Clapton 29. Heartbreaker - Led Zeppelin 30. Hard As A Rock - AC/DC 31. Sunshine Of Your Love - Eric Clapton 32. Always With Me, Always With You - Joe Satriani' 32.5 Nothing Else Matters - Metallic 33. Bohemian Rhapsody - Queen 34. When I'm Gone - Eminem 35. Chinese Democracy - Guns 'n' Roses 36. Verona - Elemeno P 37. Black Night - Deep Purple 38. Fat Bottomed Girls - Queen 39. Paranoid - Black Sabbath 40. Livin' On A Prayer - Bon Jovi 40.5. Battery - Metallica 41. Who Made Who - AC/DC 42. Hot For Teacher - Van Halen 43. Voodoo Child - Jimi Hendrix 44. Stairway To Heaven - Led Zeppelin 45. (Moved Up To Number 5.5) 46. Lonely - Akon 46.5. Pour Some Sugar On Me - Def Leppard 47. Sweet Home Alabama - Lynyrd Skynyrd 48. Sink The Pink - AC/DC 48.5. Photograph - Def Leppard 49. Are You Gonna Be My Girl - Jet 50. Make Love Like A Man - Def Leppard 51. For Those About To Rock (We Salute You) - AC/DC 52. Shake Your Foundations - AC/DC 53. Devil On My Shoulder - Billy Talent 54. Worker Bees - Billy Talent 55. Smoke On The Water - Deep Purple 56. Under The Bridge - Red Hot Chilli Peppers 57. Smells Like Teen Spirit - Nirvana 58. Walkie Talkie Man - Stereogram 59. Don't Cry - Guns 'n' Roses 60. High Voltage - AC/DC 61. Khe Sahn - Cold Chisel 62. Highway To Hell - AC/DC 63. Kashmir - Led Zeppelin 64. In and Out Of Love - Bon Jovi 65. Ramble On - Led Zeppelin 66. Purple Haze - Jimi Hendrix 67. Teenagers - My Chemical Romance 68. Give It Away - Red Hot Chilli Peppers 69. Stop Drop And Roll - Mareko 70. One Eyed One Horned Flying Purple People Eater 71. Walk All Over You - AC/DC 72. Cut The Curtains - Billy Talent 73. Live And Let Die - Guns 'n' Roses 74. I Wanna Rock 'n' Roll All Nite - Kiss 75. Message In A Bottle - The Police 76. Iron Man - Black Sabbath 77. There's Gonna Be Some Rocking - AC/DC 78. Ride On - AC/DC 79. Lights and Sounds - Yellow Card 80. Holidae Inn - Chingy 81. Rock 'n' Roll Ain't Noise Pollution - AC/DC 82. Have You Ever Needed Someone - Def Leppard 83. Not Many - Scribe 84. Holiday - Greenday 85. Hotel California - Eagles 86. Heart Shaped Box - Nirvana 87. Heaven Is - Def Leppard 88. Over The Hills And Far Away - Led Zeppelin 89. Hells Bells - AC/DC 90. Tears In Heaven - Eric Clapton 91. DT - AC/DC 92. Moneytalks - AC/DC 93. Alberta - Eric Clapton 94. Killer Queen - Queen 95. Rock This Town - Stray Cats 96. Stiff Upper Lip - AC/DC 96.5. I Love Rock 'n' Roll - Joan Jett 97. The Jack - AC/DC 98. Angie - Rolling Stones 99. Black Ice - AC/DC 100. Invisible Man - Queen I'll be always updating this list with song that i've forgotten to put in!

Topic by ajleece    |  last reply


Why "Vortex" for Vortex math and devices?

If you are new to the topic then it might give you a slightly quicker understanding than watching hours of youtube videos.I assume you have seen these various coils that make a sphere shaped magnet spin at insane speeds.They are a good start.You see by normal understanding these Rodin or Vortex coils should not be able to produce a field that rotates that fast.As with a lot of things we tried to use math to explain it in theory and than adjusted the math to match it.Vortex math was born.So how do you explain blue and red to a blind person that never saw anything?I mean in a way they actually know how it would look if they could see?Doesn't work, but we can use a Dyson vacuum cleaner ;)A lot of "tornados" add up to one giant super tornado.Spinning so fast that "all" the dirst stays behind and only clean air comes out.As in nature all the weather cells add up to one that is more powerful than the combined single ones.The tornados that form the term vortex are around the coils.But also around the entire donut as well as every single strand of wire.In any good vortex the rotational speed increases towards the center and bottom of the vortex.You can try that with some floating stuff when you drain your bathtub or sink.Try to imagine and endless tornado that runs around every wire like a spiral.The coil itself adds another spin vector to it and increases the moving speed or the single tornado.Combined it adds up to a very strong tornadoe moving very fast around in the coil pack.As this also creates a rotating field like another tornado in the donut shape it all gets twisted up.Physics as we know it won't fully explain these effects.Vortex devices that produce electricity are usually coils in a special winding configuration and pattern.Like we try to eliminate certain things with basket coils in the HF area a Rodin or Vortex coil tries to utlise these otherwise unwanted stray effects and interferences.Overunity is another term people like to use here but I leave it up to you if such a things is phsically possible with an electrical system.Vortex math tries to explain all these things demonstrated in experiments.However I found two slight flaws in the common approch.1. Only two dimension used.Unlike the coils the simplified Vortex math only operates in two dimensions.A circle instead of a sphere if you like.2. Again, unlike the coil harmony and resonance are neglected.It seems in some cases people try to draw a circle just with straight lines.While in reality you have a never ending, resonant "stream" in three or to be precise four dimensions.Is it the chicken and egg problem?Yes and no.You can only calculate something if you can fully understand it or exactly replicate it in reality.Vortex coils are just way to interpret theories and get some sort of results.And those results are the real problem.We can measure magnatic fields in strenght and direction even frequency.However we can neither make them visible in real time not measure mixed or entangled fields properly.We "see" Mars is our "red planet" but in reality it just the atmosphere, the surface is not red at all in most places.NASA has enough problems to calculated missions to outer space with enough accuracy.Just imagine they would have to do it while considering that around every path our planets make is another spinning "distraction"....That is exactly what Vortex math tries to do while eliminating common math bit by bit.You can see and hear in 3 dimensions.Maybe you are also good in drawing something in 3D on your compterscreen or 3D headset.But how many here could predict the path of a baseball in 3D like they do when watching a game?Depending on your viewing angle you might be way off....Try to know or calculate where exactly the ball is at any given monet in time and how fast it spins in which direction.....Our brains are not trained to think like this!Even if we construct things like a dome we prefer to have straight features.Sure manufacturing is one thing that needs to be affordable.But try to just calculate the support structure if all is actually fully round like a sphere should be.We avoid what is considered higher dimensions as much we can.To calculate a distance in 3D it still seems easier to use two 2D models to add up instead of true vectors.Again only through technology like computer we are able to simulate, understand and actually calculate what we need.Where we ventured around the globe and into our solar system our math was left behind.Finding workaround and good enough approximations still seems the way to go.Instead actually evolving our math to our needs we just add more and more complex formulas and calculations.To fully understand vortex math you need to let go and start thinking in 4 dimensions instead of just 2.Oh, sorry, you might be new to this...Number 4 is time of course.

Topic by Downunder35m  


Switching to LED lights for your car head lights - what you should know about it!

With LED technology getting cheaper and better almost weekly now it seems to make sense to use them in your old car.People who did it and post about it make the decisions even easier.I mean who wouldn't want to switch from pale yellow candle light to these bright white litghts showing you all in great detail?Problem is the firstly the legal side of things.Many countries now allow the use of LED replacements for many older cars - within limits.Where and if allowed it means you need to use LED systems that a compliant with your local road authorities and regulations.In a lot of countries though it is still not legal to replace incandescent head lights with LED ones.Why is this?If you read this after changing over already you will have noticed a destinct difference between the two types of "globes".The filament is very compact and in a H4 lamp the reflector is quite small and perfectly positioned as well.In comparison to (mostly the non-legal) LED replacements the light emitting surface is flat and usually a lot bigger than the filament.This means the light output and pattern changes as the reflector of your lamp is not designed to work with LED's and their bigger area of light surface.Being flat also means the LED can not really produce the same amount of light in LUX to the sides as compared to directly above.Most LED lamps compensate this with an added reflector in the front area.So we have two major problems:Not really enough light going sideways while too much light goes up and down in the LED system.Too much stray light due to the bigger surface are that puts out the light.Combined they result in light going into areas where it should not go, or not go at this level of brightness.The often used statement that now even highway signs are easy to read at night on low beam clearly highlights this problem.There is a good reason your head lamps should not shine upwards ;)What can be done to allow for the use of LED lamps in old cars?If not too old than your car already has H1/H7 lamps and indiviual for fog, low- and high- beam.For those it is now quite easy to get road legal LED replacements.Not so much though for the really old H4 systems with high- and low- beam in one lamp.Don't be fooled by your local auto shop though!Just because they might sell a lot of HID and LED lmaps does not mean what is on display for sale is actually road legal.If it does not state the corresponding certifications for your country/state than you can rest assured a cop on a bad day will have field day (or night) with you sooner or later.As said, in many countries there are now tested and legal option available.Their main difference to the cheap and uncertified ones is not their higher price alone.In comparison their more powerful LED's result in much smaller COBS -the LED strip giving the light.Reducing glare and providing a much closer match to the incanscent lamps.Why is it so hard to find a common ground and provide proper LED replacement systems?You might as well ask why you can buy a $20 amplifier or a $5.000 amplifier....When the first cars came out with LED lamps China saw the potential and provided all sorts of headlight lamps with LED's in them.Quickly they not only made it to the international markets but also gained interest for basically everyone wanting more light.Regulations were non existent back then...Even today it is next to impossible to actually provide proper numbers in terms of lumen, LUX or general brightness.What a LED provides can be quite different from what leaves the head lights.Old standards only refer to Watt, so it is no problem to find a cheap LED system that provides what a 100W lamp would get you at less than 30W on the input side...And the light color is not really specified at all in most countires.France required a yellowish light back in the day.A blue tint in your head lights was no problem with Xenon lights, so LED systems now go as high 7000 Kelvin, or close to a blueish light and as low as 3000 Kelvin or what is coming from incandescent lights.You see, finding a common ground is already hard just with the light output and color alone.There is only one real test that even today defines whether or not a head light needs adjustment or in case of LED replacements makes them illegal.The good old white wall with the markers, lines and distance mark on the floor.If you compare a properly adjusted head light on these test walls you get a very destinct pattern of light to see.Clear cut off's, brightly illuminated areas within the fields and lines and less bright areas in the outer regions - again still defined by the marks on the wall.Swapping to various types of LED replacements should provide the same patterns and brightness levels.In reality though almost all of them will only give you a very bright and undefined big area on the wall.No more dark areas with clear cut off to the bright middle section, even the formerly shadowish side areas are now well lit up.Great for you behind the wheel, bad for everyone coming the other direction, especially when wet and raining.Some people in the colder parts of the world will now what I mean when I say that some LED system will only give you good visibility when it snows if you turn them off ;)How to check for yourself if your new LED lights are any good for other people on the road?I assume you did the right thing and had your headlights checked and if required adjusted before actually putting LED lights in!Nothing is worse than trying to get more light if said lights are adjusted to point everywhere except the road.With your old light still in park in front on a straight wall on level ground, like your garage or any other wall you find.Park at a nice distance to get a clean pattern on the wall that is not too big.5 to 10 meters away should do fine.Use some painters tape or similar to mark out your desgined light pattern on the wall.Don't be too fancy, just some tape to indicate where bright light turn into way less on the wall and a few strips to indicate the cut off lines where patterns of brightness change on the wall.Leave the car where it is and put your new LED lights in.Check for yourself by how much the areas differ now.Anything above your marked cut off lines means you are blinding other drivers ahead of you.Anything way brighter than before on the sides could mean you also blind oncoming traffic on the other side of the road or freeway.A pale and low light level in these areas is not too bad and can be acceptable.Anything that clearly illuminates those formerly dark areas however should not be used on the roads.Another check is to try at what distance your old low- and high- beam start to become a bit too birght too directly look in to when you stand in front of your car during a really dark night.Look somwhere drak and move closer until you reach the discomfort zone.With your LED lights you should be able to get as close as before ...

Topic by Downunder35m