slow voltage current builder: how to increase voltage,current in ramp manner upto the desired value?

Let us assume a system requires 230V ac, 6 amp. When we switch it on, the voltage and current instantly shoots up from zero to 230V,6amp. I want the system to receive the voltage,current slowly ,i.e, when it is  switched on, the voltage,current should increase from zero in a ramp manner ,and when it reaches 230V,6amp, it should remain there till  the system is switched off.

Question by iamnimisha   |  last reply

2002 impala intake manifold gasket?

Is it difficult to change the upper intake manifold gasket on a 2002 chevy impala?

Question by jakerice   |  last reply

HP deskjet 930C

End 2006 someone raised this topic but did not show how and which screws to remove in order to lift the upper-part of the printer. Can anyone on the board tell me how? Frank3

Topic by frank3   |  last reply

How do I fix paper feed in fax /printermachine?

HP Officejet 7310xi doesn't feed without jamming using upper feed tray. Should I wipe rollers with alcohol?

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how to open logitech T400 wireless mouse?

The upper portion of my mouse i.e the right and left click button portion is displaced and has come slightly upwards .  please reply asap. thanks  with regards  Avinish Dhaka

Question by Avinishdhaka   |  last reply

hello all, some of the videos only show up as a white box

Hello all, some of the videos only show up as a white box with a green y inthe upper left corner, what do I need to download ? Thank you?

Question by FORTMAJS   |  last reply

Anyone having trouble opening the instructables home page?

Other pages on the site seem to work, but even clicking the Robot in the upper left corner gives me:  "Firefox has detected that the server is redirecting the request for this address in a way that will never complete"?

Question by roccopeterbilt   |  last reply

How to prevent slightly broken LCD multitouch screen from further damage?

Dell XT2 laptop. I would be very grateful for couple of advices. Is there a way of not spreading upper crack during everyday usage like a black hole in "Dark Water" ?

Question by DDevilPL   |  last reply

New Instructable Editor

I'm just about to list off all the sweet new features in a blog post, but right now, try out the new Instructable editor! can also get to it from the "Try the new Editor!" link in the upper right of the standard editor

Topic by ewilhelm   |  last reply

Firefox - Login | Signup is missing

Recently Firefox updated and now the "Login | Signup" is missing from the upper right corner of the webpage (attached screenshot).Current version of Firefox is Firefox Quantum 64.0.2 (64-bit).Previous to the latest series of Firefox updates, those buttons were visible.

Question by dwfunk4475   |  last reply

BAATCH code - Math Problem?

Heey! I wanna make a .BAT program that'll help me do homework. I'm lazy to type the same formula to calculator, so I wanna make a program with preset formula. I wanna make the program solve this formula: S=3,14*r2 and O=3,14*d - Surface and Circuit of a cirle (I'm not english, my english's not the best). I wanna make the program solve these formulas. When you type r=3, it will say CIRCUIT IS (r*2 and then 3,14*'the r*2') AND SURFACE IS (3,14*r2 - the 2 should be in upper right corner) When you type d=3, it will say CIRCUIT IS (3,14*d) and SIZE IS (d:2 and then 3,14*'d:2 answer'2 - again, 2 in upper right corner. Please.......

Question by NicoFilippo   |  last reply

Why are there few or no clouds in the stratosphere? Answered

        The stratosphere (STRAT  uh sfihr) lies above the troposphere. It extends from about 11km to 50km above the earth. In the lower part of the stratosphere, the temperature does not change with height. But, in the upper part , temperature increases with height.  At 50km, the temperature is about 7o/c.          Air in the stratosphere is dry and thin, and there are very few or no clouds.

Question by Waren-Neutron   |  last reply

Peltier-element: Limiting its heat by tapping the power?

Hi I have a question based upon logics and the function of a peltier-element. we all know, that you can supply power to a peltier-element to raise the temperature on it one side and lowering it on the other. So it increases the differential. Now: If we heat the "cool" side and try to radiate the heat off the hot side (eg cooling it a bit), we can get a small amount of energy off the peltier as electrical current. The current depends on the temperature-differential: The bigger the more. OK so far. Nothing new. But what made me think was the fact, that you have 2 opposite states: Heat Side C and cool side H --> Get energy out in proportion of heat-differential. Put energy in --> Side C gets cooler and side H gets hotter in proportion of energy supplyed. By getting energy OFF the peltier, you in some way, redirect some parts of the heating-energy to the electrical-output. Also that is nothing new and we all know that since energy cannot be generated but only converted (in our case from thermal energy to electrical energy). Now what puzzles me is: Does it actually affect the temperature (-differential) of the peltier, if you get energy off it? Lets imagine the following experiment: - You build something like in - Now you disconnect the load (lamp) and measure the temperature on the upper side (Away from the candle). - Wait for a steady-state when the upper side doesn't get hotter - Now turn on the lamp thus redirecting a bit of energy away from the peltier. - measure the temperature again on the upper side. Does it lower the upper temperature a bit? of course it wont be lower than the unheated state. But lets say the steady state was 55°C. Would it be like 50°C if i switch on the lamp?

Topic by Orngrimm   |  last reply

Printing a circuit on clear plastic?

Hi Guys Inside most modern keyboards, you find a rubber membrane that presses a sandwich of three layers of plastic, with the upper and lower parts having circuits on them that make the contact. Is it possible to 'print' this type of circuit at home on standard laser or inkjet printers?  I could use Amanda's method with bare conductive ink, but printing would be better. Any info appreciated ;)

Topic by wizer   |  last reply

if my sway bar link bushing n bolt broke off would the left suspension (control arms) be lowered?

Im missing the bolt n bushing on the sway bar link the upper n lower control arms are now lowered and the nut on the lower ball joint is riding on the inside of the rim. well sitting on it, im not drivin it would this be the cause? 2001 Mercury mountaineer

Question by TrishMustang   |  last reply

Why doesn't i' remember my login status, anymore?

For the last couple of months, I open my bookmark, see that I'm logged in (avatar in the upper right, with the "You, Inbox(0), Shortcuts, Logout" menu.) Then I click on one of the I'bles, and when I get to its page, I'm logged out. This used to be sticky.  What happened? I'm having it happen in IE9 and Firefox 7.0, on WIndows 7, and in Firefox 7.0 on Ubunto 10.04 and Ubunto 11.10. It's irritating.

Question by jdege   |  last reply

FM Transmitter: Please help decode diagram/power properly (Mandarin or Catonese would be helpful)

I just need to figure out how to power this thing! Notice the positive marks in both upper corners, the negative in both lower? The large circle is the microphone, which is fully wired. The smaller circle is the frequency modulation, which is all set as well. The underside only has holes where the gray squares are and is otherwise clean (exception being one spot where the two mounting prongs of the microphone pushed through.) Thanks

Topic by owhy   |  last reply

Variable power supply? Answered

Is there a fairly simple circuit, method to making a desktop power supply running on 240v a.c mains supply with a user controlled variable output say 0-24v D.C with variable ampage upto say 1 amp. I may be over simplicating thing in my head but is it just a case of a transformer taking my mains input down to the upper most requirement ( 24v @ 1amp ) on the output, and the using some type of variable resitors on the output to further restrict the output to my requirement. I would be grateful for any guidance and information on this topic. Thanks to the community in advance.

Question by mickcaulton   |  last reply

How can I project a night sky on a tent ceiling?

I'm getting married in September and I want a night sky projected on the tent at my wedding. I love the images from Harry Potter in the Great Hall (I know that it won't look exactly like it because of the tent angles). The tent is a 40'X40' open sided. I only care that the upper half is projected. The bottom edge surrounding the tent is going to have string lights wrapped in grapevines possibly with wisteria and amaranthus hanging from it. Does anyone have any ideas on how to make this work, and how to rig the projectors to the tent ceiling poles?

Topic by lpfan3217   |  last reply

Compressing home made biogas

Hi I'm working on a project where we are using an anaerobic digester along with a series of gas scrubbers that yields biogas containing roughly 80% methane (ch4) and 20% oxygen. I know that this proportion of methane is well above the upper explosive limit of methane (about 15% methane by volume) but the presence of that much oxygen makes me nervous.  Am I going to have trouble compressing this gas mixture without blowing a new hole in my head? I am planning on compressing the purified biogas to about 20psi at between 60-80 degrees farenheight and in a respectably blast proof gas container.  please help! (Trying to help our planet!)

Question by Jdouenias   |  last reply

parallel light bulbs? Answered

Is there any way of connecting multiple fluorescent light bulbs *THIS* to 1 power plug....i'm a newb, so if this is pretty complicated, i'm gonna need some articles :) the reason i ask this is because i'm thinking about constructing a (full room) black light in it's own sweet casing. it would go around my whole room around the perimeter (around the upper edge, touching the ceiling) so ya...i have enough construction knowledge to build the casing and everything else, BUT i do not know hardly anything about electrical stuff...which is why i have you guys :) so ya...any help (or different solutions other than light bulbs) would be greatly appreciated. thanks :)

Question by miqt   |  last reply

Can IR light from an Infrared LED pass through semi-opaque acrylic?

I'm making a modification of the Table for Electronic Dreams ( and want to expand it with white LED's that turn on and get brighter as an object above it gets closer to the surface of the table (I'll be replacing the LED's in the original instructable with blues).The only (and thus, the cheapest) way I can think of sensing this distance without cutting holes in the upper piece of acrylic is to use an IR transceiver on the circuit board and connect this to the white LED. Would this work? I'll be using .25-inch white acrylic if that makes a difference.Any assistance that you can provide is greatly appreciated.

Question by SJBarag   |  last reply

Help with an arduino 16x2 LCD sketch?

Hey all. Im new to arduino and have bought a 16x2 lcd to learn more about the ide. I was able to write the simple text. Then i also scrolled it. But now i want that the upper line should be static and the lower line should move. How can i achieve this effect. Also when scrolling a piece of sentence (lets say right to left), when the sentence goes completely toward left, it doesn't appear from the right until the whole sentence has not disappeared. This leaves a lot of space in between. I want that the moment text touches the left, it starts coming back from the right ( like what was there in the old snakes game that came with all primitive phones).  Plz reply fast......Thanks a lot! :)

Question by SnehilSensei   |  last reply

Do you know any great physics/chemistry projects? Answered

To a upper-high school academic level. I've been just doing a homopolar motor and supercooling water. Nothing very advanced or interesting. Do you guys know any good projects? Pertaining to Chemistry, I've seen most on Instructables and few on kentchem. Pertaining to Physics, blast away! I've done limited projects although I have few bookmarked for later. Answers that can be made at home are appreciated! Additionally, answers that can be made at quickly with a somewhat limited number of materials are also appreciated. Well since answering stopped Top answers were from FoolishSage, The Skinnerz, and gruffalo child. FoolishSage wins because of the amount of projects provided. But these were all great answers.

Question by Sh3lsh   |  last reply

How to fix a PS3 controller??

So i was playing Skate 2 when I had to go into my kitchen and put away some things. I came back, but forgot I put the controller under the gaming chair when I got up, so I sat, and the chair rolled right over the controller. I looked at it and the left joystick was half out. I pushed it back in and it was weird. It wasn't always in the middle. It would stay up, or left, or upper left, lower right, etc. I pulled the rubber part off and realized that the rod connected to the controller had to go in a slot in the rubber part. But considering the outside of the rubber part have to go INSIDE the controller, and it's hard to do. I tried unscrewing the bottom, but idk what kind of screw it is. I NEED HELP!

Question by Flumpkins   |  last reply

Vibration comparison

I'm trying to compare two wildly different measurements, but I don't know enough about the physics of sound to even know what information I'm missing. I don't need exact numbers: some upper and lower limits would be fine, and perhaps even "back of the envelope" calculations in case the required information can't be found. I'd appreciate some advice on the formulas I need and what measurements am I still missing.  Object A is producing a sound whose intensity measures 25 dB at a distance of 1 meter.  This sound is, roughly speaking, a band-limited sawtooth wave with a fundamental frequency of about 35 Hz.  Object B is being driven up and down a distance of about 0.5 mm with an acceleration of 0.3 times that of gravity. The sound doing this is a sine wave with a frequency of 35 Hz. I'd like to compare the peak accelerations experienced by the two objects.

Question by CuriouserAndCuriousest   |  last reply

Controlling a 12v Wiper Motor?

Hi all, I'm a bit of a noob with electronics and wondered if anyone could help me with a project, I would like to control the speed of a wiper motor for use in a small powered saw. Ideally using mostly the upper end of the motors speed, are there any cheapish products I can buy off the shelf to wire together to give me (UK) mains power going in and the max safe voltage/amperage out to run the motor, plus speed control. I say max voltage/amps as I have read elsewhere that the motor can handle a bit more than just 12v. I have searched a good few electronics kit sites and found things that sound like what I want, but I guess I'm just not sure if it actually is. As always I would be grateful for any help.

Question by Squibo   |  last reply

how to design Wind Powered Water Lifting System?( against gravity ) it should be waterwheel windmill? Answered

1.      The system will be tested for 6 minutes in door using one fan that generates “wind” at three different speeds (Time starts when the fan is turned ON giving 2 minutes for each speed starting with the lowest speed). The fan is provivded 2.      The setting of the filled lower tank and upper empty tank is provided by the organizer. The details of the setting 3.      The minimum distance between any part of the system and the fan should be at least 190 cm. 4.      All material used in the systems must be safe, harmless and accessible to everyone in normal market. Systems should need no safety protection and no grid electricity 5.      Electric or electronic components are not permissible. 6.      The cost details of the system components should be prepared and presented by each team. 7.      Each team will be given 5 minutes to demonstrate all aspects of their system. 8.      Each system dimensions are limited to 100 cm width, 100 cm length, and 180 cm height.

Question by lulu114   |  last reply

Wiring DPDT 20 Amp Switch

I am in the process of building a MAP Sensor for my vechicle using a 20 Amp DPDT switch with an 100k Potentiometer. I want to use one side for going back to the origianl and the other side for the modification. I also want to have a green light showing when it is in the original condition and a re (warning) light for when it is in the modification mode. Can I do this? If so How about showing me how to do so. I have attached a picture of what I am trying to do. The toggle switch has 6 blades and I don't understand the schesmatic in hooking it up. I am attempting to make two into one. the upper switch is to control the Potentiometer on the left with the green and red lights above it. The bottom switch is to control the one on the right. When both switches are in the original circuit, both gree light should light up. When they are in modifying mode both red lights should light up. Hope you understqnd wht I am trying to say here.

Topic by DocBunner   |  last reply

Need help with audio trigger for do I generate a beep/click 300m away?

Hey guys, I have a DSLR Canon 550D camera with Magic Lantern modified firmware installed on it. This firmware allows the camera to be triggered by sound, utilizing the cameras onboard mic. The level of sound required to trigger the camera can be adjusted. What I would like to do is have the ability to trigger the camera from quite a distance with some sort of audio trigger. If I have this trigger close enough to the mic and adjust the levels it would only need to make a decent click. To get decent range I am assuming I will need to use a radio device? Can anyone think of anything cheap and compact that could work as a trigger? Using walkie talkies is the obvious thing that comes to mind but these are rather bulky....ideally the trigger would be small enough to clip/tape to the camera. In terms of range, 200-300m would likely be the upper limit. Any thoughts would be appreciated :)

Question by tig5   |  last reply

Tentacular awesomeness pushes limits of body image

From The Design Blog, via NOTCOT: Pushing the boundaries of current upper-limb prosthetic design, designer Kaylene Kau has created a prosthetic arm that supports the dominant functioning hand in accomplishing day-to-day tasks with ease and efficiency. Featuring a flexible design, the prosthetic arm adjusts to allow a variety of different grips to hold a variety of objects with minimum fuss. The Prosthetic Arm also integrates motors and cables, which help the user control the amount of arm curls required for different tasks. Presenting a simple yet effective design, the new prosthetic limb makes users self-reliant, as they can carry out their everyday tasks without any assistance. Of course, any advances in prosthetics is welcome, but I bet the first thoughts of most people reading this here were either Cool!  I could be an octopus! or Woah - I want one of those on my next Hallowe'en costume! I'd really like to see a video of it in action - I can't decide if it would be cool or creepy. I also imagine that an arm like this would be (relatively) easy to engineer for the amateur.

Topic by Kiteman   |  last reply

What excellent examples in CAD of low drag coefficient pickup trucks exist that are available on the internet?

Vehicles have been designed to minimize the aerodynamic drag with notable success. Production candidate vehicles (such as Aptera, Twike, and Honda Insight) achieving drag coefficients of 0.25 down to 0.11. Solar Challenge vehicles have reached 0.07. Nose cone and fastback upper and sealed or faired lower body designs can achieve significant reductions in drag, and are worth attention. I am attempting to optimize a design for pickup trucks and cross-over utility (CUV) vehicles that are based on the same basic chassis design. Can anyone contribute designs, examples, or sources of information on optimized pickup design? BTW, I am simultaneously searching for a safe design that has the vehicle center of gravity at or below the axle height, as it should be to prevent roll-over accidents. Risk of injury and death are significantly higher in pickup trucks and CUVs than cars, and now pickups and CUVs account for more than 50% of new vehicle sales. This tragic fact needs to be reversed with safer design.

Question by rkh986   |  last reply

My computer locks up with an audio loop, help! Answered

I recently upgraded my hardware (I put in two 8600 GT's in SLI, and an E6850, both used), and shortly after, my games began to lock up. Whatever was on the screen would stay there, and the last second of audio would loop. The only way to get out of it was a hard reset. Then I noticed when I unplugged my other two hard drives, games wouldn't freeze up anymore. So I replaced my 400 watt PSU with a 550 watt, with 50 amps on the 12 volt rails. Everything seemed to clear up, until today, when I was browsing Newegg and listening to Audioslave (not very resource intensive), and it locked up with the same symptoms for no apparent reason. I'm getting worried now, as I shelled out 75 bucks for a decent PSU and the same stuff is happening. My CPU idles in the upper 30's to lower 40's, and peaks at 60 C in games. I know it's a bit toasty, but it shouldn't be hot enough to cause this sort of problem, right? So if anyone has any ideas about what's going on, any help is appreciated.

Question by RelaxedSoup   |  last reply

New camera?

Well I'm getting a new camera and have come to the choosing part, basically the upper limit is £180 and I'm torn between two but also looking for other suggestions. It's to replace my fuji finepix S5600 that was stolen. my requirements are as so: *Min 10x optical zoom *Needs to have shutter speed adjustment of at least 15 seconds down to 1/2000th of a second *A decent amount of megapixels (6 or more) *Full aperture adjustments would be nice but up to F8.0 is acceptable *Built in flash *Preferably uses standard batteries like AA, unless it's canon, got a load of them already I've already Seen two I like, being most familiar with Fuji and canon drew me towards them. The Finepix S1000FD is the evolution of my older camera and the controls remain the same for the most part, Has 12x zoom which is better and 10 megapixels resolution... The canon SX100 is cheaper and only has 10x zoom, it does do slightly faster shutter speeds but it's a marginal difference, it also includes optical image stabilisation which would be nice, the fuji has no mention of this... Any other suggestions for potential cameras are very welcome, please help me choose between these two or others...

Topic by killerjackalope   |  last reply

How to square wave ---> triangle wave?

Currently I have developed a flyback driver that is a semi-cross between a classic ZVS circuit and a 555 type driver, mainly just using a few comparators (one to create a triangle wave and 2 others to respond to the upper and lower peaks and drive MOSFETs. This allows me to create a modified sine wave with adjustable duty cycle.) This topology is even more powerful than the ZVS driver at 12V, as I got some INSANELY thick arcs!! However the MOSFETs get a little too warm, and I was forced to use sil pads to galvanically isolate the drain from the CPU heatsink. They seem to have really poor thermal characteristics as the heatsink stays cold while the transistors get uncomfortably hot within seconds!! To make this thing operate at the resonant frequency of the flyback, I think I will a feedback coil that would get "squared up" using a resistor and zener diode. I need to convert that signal into a triangle / sawtooth wave of fixed amplitude. A simple RC type circuit is not too suitable because as the frequency goes up or down, the amplitude of the voltage across the capacitor changes proportionally.What circuit will allow me to convert a square wave directly to a triangle wave of fixed amplitude????

Question by -max-   |  last reply

Exoskeleton Helps the Paralysed Walk

Exoskeletons frequently hit the news as projects to make super-soldiers, but a new, more slimline version has bee built by Israeli company Argo Medical Technologies. Inspired by the paralysis of one of their own engineers, ReWalk allows wearers to walk, use stairs, stand and sit.The wearer switches between "modes" with a tap on a wrist-pad, then controls the actual motion by shifting their upper body-weight. For instance, they would hit "stand", then lean forward to make the ReWalk straighten its exo-legs. The device is much more streamlined than some other systems, run from a very flat pack-pack, and can be worn all day, but is only suitable for paralysis victims who still have good control of their arms and shoulders.ReWalk seems much simpler and lighter than other exoskeletons, but that seems to be because the designers have not tried to replace the entire walking function - balance is still down to the wearer, using crutches, but I imagine practice could reduce that to sticks, or even a single stick.Weight and fitness seem to be factors as well - the man in the video is was an Israeli paratrooper, injured on duty, and there are no shots of the rather portly wheel-chair-bound inventor wearing the ReWalk, but I think you'll agree it would still be a major benefit to an awful lot of people.This video is in German, but shows more shots of the exoskeleton, and has clips of the designer discussing his project.

Topic by Kiteman   |  last reply

Trying to figure out how ultrasonic humidifier detects low water level

Hello all, I'm currently working on a home automation system and have decided I want to throw my fragrance diffuser into the mix. What I'm trying to accomplish is I'd like the diffuser to come on whenever the unit has power so I can simply control it with a Sonoff SV. I was originally planning on just replacing the guts with an Arduino Nano or something until I tore into it and realized I have absolutely no clue how this thing detects when the water level is low! There's no sort of float switch or resistive fluid detection. In fact, the only part that has contact with the fluid is the ultrasonic transducer. I'm curious if anyone can look at the PCB and give me some more insight as to what's going on. On the far left the five pins coming into the board is the cable connector for the buttons and LEDs, the two large pins beneath that are the buzzer for making beeping noises when buttons are pressed, The SMD IC towards the middle is from what I can tell the brains of the operation. The three large pins (two with solder) near the top center are where 24vdc comes in. The two large pins on the upper right are for the fan and the two large pins on the bottom right are for the transducer. If anyone has any insight as to how this thing reads a low water level it'd be very much appreciated. Thank you!

Question by harry88   |  last reply

Controlling a motor with a touch screen ?

So i am trying to control a motors speed using PWM (running through a transistor). I know how to make that happen but i am unsure how to use a touch screen to control the motor,  I have one of the test codes that is a touch pad 0-9 with enter and clear. I was wondering if there was a way that i can punch the number in push enter and have the motor run at that speed(starting with just 0-255) The touch screen is 3.2LCD TFT Touch Screen SD Reader;=item4168c41ead The code is // ITDB02_Touch_ButtonTest (C)2010 Henning Karlsen // web: // Modified to work with UTFT on Mega w/Arduino 1.0.1 (C)2012 Otmar Ebenhoech, // // This program is a quick demo of how create and use buttons. // // This program requires the ITDB02_Graph library (8bit mode) // or ITDB02_Graph16 (16bit mode). // // It is assumed that the ITDB02 module is connected to a // ITDB02 Shield, a ITDB02 Mega Shield or that you know how // to change the pin numbers in the setup. // #include #include // Declare which fonts we will be using extern uint8_t BigFont[]; // Uncomment the next line for Arduino 2009/Uno //UTFT myGLCD(ITDB32S,19,18,17,16);   // Remember to change the model parameter to suit your display module! //ITDB02_Touch  myTouch(15,10,14,9,8); // Uncomment the next line for Arduino Mega UTFT myGLCD(ITDB32S,38,39,40,41);   // Remember to change the model parameter to suit your display module! ITDB02_Touch  myTouch(6,5,4,3,2); //// //// ////   ////THIUS IS WHAT I ADDED ETK int motor = 9; ////    //// //// //// int x, y; char stCurrent[20]=""; int stCurrentLen=0; char stLast[20]=""; void setup() {//// //// //// //// tHIS IS WHAT I ADDED ETK pinMode (motor, OUTPUT); //// ////   ////    //// // Initial setup   myGLCD.InitLCD(LANDSCAPE);   myGLCD.clrScr();   myTouch.InitTouch(LANDSCAPE);   myTouch.setPrecision(PREC_MEDIUM);   myGLCD.setFont(BigFont);   myGLCD.setBackColor(0, 0, 255);   // Draw the upper row of buttons   for (x=0; x<5; x++)   {     myGLCD.setColor(0, 0, 255);     myGLCD.fillRoundRect (10+(x*60), 10, 60+(x*60), 60);     myGLCD.setColor(255, 255, 255);     myGLCD.drawRoundRect (10+(x*60), 10, 60+(x*60), 60);     myGLCD.printNumI(x+1, 27+(x*60), 27);   } // Draw the center row of buttons   for (x=0; x<5; x++)   {     myGLCD.setColor(0, 0, 255);     myGLCD.fillRoundRect (10+(x*60), 70, 60+(x*60), 120);     myGLCD.setColor(255, 255, 255);     myGLCD.drawRoundRect (10+(x*60), 70, 60+(x*60), 120);     if (x<4)       myGLCD.printNumI(x+6, 27+(x*60), 87);   }   myGLCD.print("0", 267, 87); // Draw the lower row of buttons   myGLCD.setColor(0, 0, 255);   myGLCD.fillRoundRect (10, 130, 150, 180);   myGLCD.setColor(255, 255, 255);   myGLCD.drawRoundRect (10, 130, 150, 180);   myGLCD.print("Clear", 40, 147);   myGLCD.setColor(0, 0, 255);   myGLCD.fillRoundRect (160, 130, 300, 180);   myGLCD.setColor(255, 255, 255);   myGLCD.drawRoundRect (160, 130, 300, 180);   myGLCD.print("Enter", 190, 147);   myGLCD.setBackColor (0, 0, 0); } void updateStr(int val) {   if (stCurrentLen<20)   {     stCurrent[stCurrentLen]=val;     stCurrent[stCurrentLen+1]='\0';     stCurrentLen++;     myGLCD.setColor(0, 255, 0);     myGLCD.print(stCurrent, LEFT, 224);   }   else   {     myGLCD.setColor(255, 0, 0);     myGLCD.print("BUFFER FULL!", CENTER, 192);     delay(500);     myGLCD.print("            ", CENTER, 192);     delay(500);     myGLCD.print("BUFFER FULL!", CENTER, 192);     delay(500);     myGLCD.print("            ", CENTER, 192);     myGLCD.setColor(0, 255, 0);   } } // Draw a red frame while a button is touched void waitForIt(int x1, int y1, int x2, int y2) {   myGLCD.setColor(255, 0, 0);   myGLCD.drawRoundRect (x1, y1, x2, y2);   while (myTouch.dataAvailable());   myGLCD.setColor(255, 255, 255);   myGLCD.drawRoundRect (x1, y1, x2, y2); } void loop() {   while (true)   {     if (myTouch.dataAvailable())     {;       x=myTouch.getX();       y=myTouch.getY();             if ((y>=10) && (y<=60))  // Upper row       {         if ((x>=10) && (x<=60))  // Button: 1         {           waitForIt(10, 10, 60, 60);           updateStr('1');         }         if ((x>=70) && (x<=120))  // Button: 2         {           waitForIt(70, 10, 120, 60);           updateStr('2');         }         if ((x>=130) && (x<=180))  // Button: 3         {           waitForIt(130, 10, 180, 60);           updateStr('3');         }         if ((x>=190) && (x<=240))  // Button: 4         {           waitForIt(190, 10, 240, 60);           updateStr('4');         }         if ((x>=250) && (x<=300))  // Button: 5         {           waitForIt(250, 10, 300, 60);           updateStr('5');         }       }       if ((y>=70) && (y<=120))  // Center row       {         if ((x>=10) && (x<=60))  // Button: 6         {           waitForIt(10, 70, 60, 120);           updateStr('6');         }         if ((x>=70) && (x<=120))  // Button: 7         {           waitForIt(70, 70, 120, 120);           updateStr('7');         }         if ((x>=130) && (x<=180))  // Button: 8         {           waitForIt(130, 70, 180, 120);           updateStr('8');         }         if ((x>=190) && (x<=240))  // Button: 9         {           waitForIt(190, 70, 240, 120);           updateStr('9');         }         if ((x>=250) && (x<=300))  // Button: 0         {           waitForIt(250, 70, 300, 120);           updateStr('0');         }       }       if ((y>=130) && (y<=180))  // Upper row       {         if ((x>=10) && (x<=150))  // Button: Clear         {           waitForIt(10, 130, 150, 180);           stCurrent[0]='\0';           stCurrentLen=0;           myGLCD.setColor(0, 0, 0);           myGLCD.fillRect(0, 224, 319, 239);         }         if ((x>=160) && (x<=300))  // Button: Enter         {           waitForIt(160, 130, 300, 180);           if (stCurrentLen>0)           {          for (x=0; x             {               stLast[x]=stCurrent[x];             }             stCurrent[0]='\0';             stCurrentLen=0;             myGLCD.setColor(0, 0, 0);             myGLCD.fillRect(0, 208, 319, 239);             myGLCD.setColor(0, 255, 0);             myGLCD.print(stLast, LEFT, 208);             ////             ////              ////             ////THIS IS WAHT I ADDED ETK             analogWrite(motor,stLast);             ////             ////              ////             ////           }           else           {             myGLCD.setColor(255, 0, 0);             myGLCD.print("BUFFER EMPTY", CENTER, 192);             delay(500);             myGLCD.print("            ", CENTER, 192);             delay(500);             myGLCD.print("BUFFER EMPTY", CENTER, 192);             delay(500);             myGLCD.print("            ", CENTER, 192);             myGLCD.setColor(0, 255, 0);           }         }       }     }   } } The stuff i added has these //// on top and bottom with a comment "THIS WAS ADDED  ETK" the part that dont work is "analogWrite(motor,stLast);" and stLast is a char so it give me char to int error. And as you can tell i am no good at this so anything that can point me in the right direction would be greatly appreciated ETK

Question by etkoehn 

Temperature and duty cycle controlling PWM help needed! Answered

Hello, I am working on a Hydrogen generation project. I am using a PWM (pulse width modulator) to control the Generator from going into thermal runaway. However, the current PWM's on the market dont offer temperature control. Only duty cycle control. So I need some help here. I need a way to control a potentiometer to increase or decrease resistance based upon a temperature range from 80 to 95 degrees. I dont want this to turn the unit off, only lower the duty cycle when the peak temp is reached. Then also, when the unit is cold on start up, it would release full amps into it until it reached it peak operating temp. The idea is to make a PWM control the generator via duty cycle (amperage draw) and temperature. Make it a "set it, and forget it" system. My thoughts are using two surface mount thermostatic switches. One for low limit the other for the high limit. Then a relay and another potentiaometer. Theory of operation: On initial start up, the generator is offered full amperage draw of 40 amps(100% duty cycle) until it reaches its operating temperature of 80 to 95 degrees. Once it reaches the peak of the operating temp the upper limit switch kicks open causing a relay to offer a differing resistance (80% duty cycle) that would effectively make the PWM still keep producing hydrogen, but cool down. When or if the lower limit of 80 degrees is reached the lower limit thermostat would close allowing again 100% duty cycle to the generator.  Thus, this system would keep the generator operating at an optimal temperature at all times regardless of outside temperature, and conditions. Current PWM's require the user to manually get them set. If the outside temps are colder the system will work less effectively. If the outside temps are hotter the temps may cause thermal runaway. All operating conditions require the user to be constantly fiddling with, and keeping an eye on the amp draw, temps, and voltage. This means eyes not on the road while driving. Bad ju-ju. I'd like to make this device super simple to operate, and build. With off the shelf items, not custom IC's. Any ideas?

Question by ydeardorff   |  last reply

circuit troubleshooting help

Hi- First on an unrelated note, does anyone besides me see "A fatal, non-recoverable error has occurred" over on the Makezine forums when you try to sign in? I've been getting that for weeks! Anyway... I'm working on a variable power supply that uses a 317 to regulate the 18 volts coming from a laptop switching supply. There are two 5k 10-turn (for precision) pots with a switch so that you can have two "preset" voltages and switch between the two of them at will. There's a single output. There's also a little lamp (I used a micro mini 12v lamp instead of an LED because that's what I had) that goes on above the pot that's currently switched in. The circuit I built (schematic is below) seems to work more or less fine. 'cept there's two strange issues: First, although the pots are linear (not sure if that would make the difference or not), they seem to "flatten out" toward their upper range. The first six turns gets you from 1.2 to about 16.5 volts. Then the last four turns either don't change anything or they do so in _very_ fine increments so that you only get from 16.5 to just over 17 volts. That's in four whole turns of the knob. This happens for both pots. The second stange thing is that turning the non-activated pot will affect the current voltage. When you increase the resistance (turn the knob to the right), the voltage level actually drops! Conversely, turning it to the left will increase the voltage. Remember, this is the switched-off pot. The switched-on pot works as it should (barring the mentioned weirdnesses). It looks like how much the voltage changes depends on how many turns you've given the activated pot. I suspect this has to do with me using a SPDT switch instead of a DPDT and maybe some voltage / current bleeding through the lamps and into the adjust pin, or something. But I ca/n't figure out why the switched-off pot would do anything. Anyway, take a look at the schematic. Is there anything I've done wrong that I'm missing? Should I, um, switch (*cough*) to a DPDT switch (something like the second schematic)? I used the SPDT cuz that's what I had. Anyy help is appreciated, Thanks!

Topic by deadbilly   |  last reply

Lost larynx to cancer, now use electronic voice, battery powered. Feel it could be improved - refine electronics?

After losing my larynx to cancer last year, i now use an "electro larynx" ( a great device which translates the vibrations my mouth makes when i "speak" with a rubber tube (the exact same as the one my dentist uses to extract excess saliva) in my mouth. The vibrations are transmitted somehow to a vibrating rubber disc inside a handheld device. There are a few other bits too technical for me to understand and describe, but the end result is an electrical voice a bit like Stephen Hawking's. The machine has a plastic disc built into the lid, held in place by a rubber gasket round the edge, which is made to be pressed against the underneath of the chin or the upper neck. When the laryngectomee speaks,  the vibrations of the throat cause the disc to vibrate, which in turn oscillates a small plastic rod underneath the centre of the disc. This rod runs through the centre of a rubber disc, which is vibrating at high speed because the laryngectomee also presses a button when (s)he speaks, causing it to do so. The vibrations somehow pick up the voice vibrations and turn it into electronic speech. Underneath the rubber disc is a some sort of coil of copper wire almost the full diameter of the machine, and there are 2 pieces of wire soldered into place , too. I don't have a clue about electronics or really anything, so i'm hoping someone out there can make sense of this mumbo jumbo. I'm sure that having a look at the website will help. As I said, normally the device is pressed under the chin, but my neck and chin are rock hard from having loads of surgery, so they don't vibrate - the clever people came up with the solution for people like me: a thick rubber cap fits over the top of the device with a hole through the middle, 5mm maybe. into that is inserted the piece of dentist tube i mentioned earlier. this somehow does the trick, and once more i have the miracle of speech! Now, as I said, this machine is amazing, and certainly beats having to write everything down. trouble is, it has a volume control wheel which is so difficult to get into the right spot, it goes from way too loud to almost inaudible. Now, having seen some of the stuff you guys come up with on here, and the apparently relative simplicity of the machine, i was wondering if anyone could come up with a solution to my quandry....Yours, speechless, Dave.

Question by DavidK75   |  last reply

Need help with Code to control servos with an Arduino?

The code will compile but when I connect the servos I start getting errors on the serial port. any help on this would be great #include   Servo myservo;  // create servo object to control a servo Servo myservo2; // a maximum of eight servo objects can be created   int pos = 90;    // variable to store the servo position   // set a variable to store the byte sent from the serial port int incomingByte;   void setup() {   // start sending data at 9600 baud rate   Serial.begin(9600);   myservo.attach(9);    // attaches the servo on pin 9 to the servo object   myservo2.attach(10);  // attaches the servo on pin 10 to the servo object }   void loop() {   // check that there's something in the serial buffer   if (Serial.available() > 0) {     // read the byte and store it in our variable     // the byte sent is actually an ascii value     incomingByte =;     // note the upper casing of each letter!     // each letter turns a motor different way.        // start of left laser sweep, moving left 90 degrees.     // arrow laser spins and points to left.     if (incomingByte == 'L') {     Serial.println(incomingByte);         myservo2.write(180);                         // send servo 2 to the 180 degree position and stay     for(pos = 180; pos > 90; pos -= 1)  // goes from 90 degrees to 180 degrees   {     // in steps of 1 degree     Serial.println(pos);     myservo.write(pos);    // tell servo to go to position in variable 'pos'         delay(15);                       // waits 15ms for the servo to reach the position   }     for(pos = 90; pos<=180; pos+=1)     // goes from 180 degrees to 90 degrees   {                                    myservo.write(pos);              // tell servo to go to position in variable 'pos'     delay(15);                       // waits 15ms for the servo to reach the position     }     }             // start of right laser sweep, moving right 90 degrees.     // arrow laser spins and points to right.         if (incomingByte == 'R') {      Serial.println(incomingByte);      Serial.println(pos);     myservo2.write(0);                          // send servo 2 to the 0 degree position     for(pos = 0; pos < 90; pos += 1)  // goes from 90 degrees to 0 degrees   { Serial.println(pos);                                 // in steps of 1 degree     myservo.write(pos);              // tell servo to go to position in variable 'pos'     delay(15);                       // waits 15ms for the servo to reach the position   }     for(pos = 90; pos>=0; pos-=1)     // goes from 0 degrees to 90 degrees   { Serial.println(pos);                                   myservo.write(pos);              // tell servo to go to position in variable 'pos'     delay(15);                       // waits 15ms for the servo to reach the position     }     }         // if a S is sent make sure the servos go to 90 degrees     if (incomingByte == 'S') {     Serial.println(incomingByte);     Serial.println(pos);     myservo2.write(90);     myservo.write(90);                              }   } }

Question by DonC_WSU   |  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

Motorized Panoramic head with microcontroller

Hi All, I want to build a motorized panoramic head. It must be made in PIC or ATMEL because I have only these options. Arduino board are not available to me  How it works.  Its basically controlling two stepper motors using inputs from photographer. Photographer inputs values in parameters and than microcontroller uses these parameters to rotate camera frame and take pictures. Parameters are as under: There are two stepper motors. One motor rotates frame of camera on x-axis and one rotates it on y-axis.  1. For x-axis motor parameters    a. Total numbers of steps to rotate.    b. One motor movement = 1 stepper motor step or more. For example we can move stepper 2      steps in on movement    c. After each movement (point#2) It takes image or press camera button by using relay or optocoupler    d Time Delay : When camera takes picture it takes time to save on memory card. We can define time in seconds as per picture size.    e : When it completes total number of steps defined in step#1. It moves back to its zero position. 2. For Y-axis moto parameters     a: When first motor completes its full number of steps than y-axis motor is activated.     b: y-axis: Total number of steps      c: one movement = how much motor steps. just like x-axis motor parameter     d:   Time Delay : same as x -axis motor. time delay after tilting frame.      e: y-axis motor just performs only one movement. Than again it activates x-axis motor.     f: Panoramas are made in multi rows. so this process of x-axis and y-axis motor activation should keep on going. It is terminated when y-axis motor completes its total number of steps. So the whole process is like this Turn on microcontoller  Add parameters for x-axis and y-axis motors click on start button microcontroller starts rotating frame on x-axis Frame start moving in steps. Than frame completes its first x-axis turn now microcontroller activates y-axis motor. Y-axis motor tilts frame upper arm in one direction.   code checks it is Y-axis motor final movement or more to come. If more than it activates x-axis motor. X-axis motor starts repeating whole process which it previously did. Than after full movement on x-axis and it activates y-axis motor. This process is terminated when total movement defined for y-axis motor is achieved. CAN ANYBODY MAKE ITS CIRCUIT AND PROGRAM CODING ? I M TOTALLY BLANK IN MAKING CIRCUITS AND WRITING CODES.

Topic by diy high speed photography 

How can I create a PPM-generating device whose output can be recorded as audio?

Dear Community,          In the late 80s and early 90s, the whole Teddy Ruxpin craze took off, and there were many spin-offs on this.  The basic idea was that the toy had a cassette player where one channel was directed to an audio circuit in the usual way, and the other channel had animation synchronization code directed to some sort of receiving circuit which controlled motors to make the mouth and eyes move so it would appear to be telling a story or singing a song.  My favorite instance of this (which I had as a child), is the Ideal Big Bird Storymagic based on the famous Sesame Street character.  There were so-called "satellite toys", Cookie Monster and Oscar which connected to Big Bird via a special patch cord, and they talked along and helped Big Bird tell the story.  I never had those though.  Different fans tell me that the animation sync code is Pulse-position modulation, the same code used over radio waves to guide remote controlled cars and helicopters.  I'm not sure if this is true or not.  I've looked at it in a waveform editor, and there appears to be some amplitude modulation going on here too.  (Please see below).  The highlighted (white) section is the span of two words.  The right (lower) channel shows the voice speaking these two words, and the left (upper) channel shows what happens to the code (which really sounds like a fax machine) as he moves his jaw down, up, and down again in time with the words.  Is this PPM, and if not, what is it? Now that I'm in my mid 20s, and I work with young children, I found one of these Ideal Big Birds on Ebay in great working order.   I'm wondering if it's possible to try to re-create what the manufacturers used to create this sync code in the first place.  Sesame Street created many nice "regular" story / music tapes with Big Bird as the central character.  I thought it might be cool to take some of these (especially the Follow That Bird soundtrack) and add the sync to make my own sort of unofficial storymagic tape (just for fun, and for my students, not to sel or share, as this would be a copyright issue).      I'm wondering if some sort of 1KHz oscillator-like device could be built that has levers of some kind, which could be routed through a DAW or a mixer, which would allow one to perform along with a program, and place the appropriate modulation envelopes into the stream of PPM to place the movements?  I think there are at least two kinds of modulation in the code; that for the beak, and for the eyes.  There must be other kinds of modulation for Cookie Monster and for Oscar.  If something like this seems practical and feasible, I'd enjoy learning about it, just for the fun of it.  If it is possible, I am also wondering how or where I could have it built, and for what sort of budget, as I am far better with my ears than with the soldering iron.  I have tried and tried, to no avail, to find someone in the “talking toys” community who knows how this was originally created.  Let me know if you'd like me to send you a clip of the audio file.  Here's a link to someone else's on Youtube so that you can see what I'm talking about.  Thank you so much for taking the time to read all of this senseless ramble!! Thanks a ton for any insights that you have!!!  I apologize in advance for the inherent nutty-ness of this post! ;)  Sincerely, Jessica

Question by jtsoundtech   |  last reply

A kind request: Google Science fair vote

I recently entered my Science Fair project in the Google Science Fair, an international science competition in which entrants can build, research, discover etc. anything they want to. For my entry, I researched on how prosthetic limbs can be controlled by thought alone and found that much of the mathematical analysis of the brainwave data had to be improved upon in order to make such a technology usable. Here is a brief synopsis, in case you were interested: ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------- My project is, at its most general level, based upon the idea of the brain-computer interface.In this sense of the definition, anything we use to interact with machines is a brain-computer interface, including our fingers. However, amputees often face difficulties after the loss of such a vital method of interaction. Through research, I found that a current medical device, the Electroencephalograph (EEG) could be implemented as a direct brain-machine interface; in other inputs on a computer (such as a cursor) could potentially be operated by thought alone. However, I also learned that, although EEG technology has been in existence since circa 1920, it still suffers from the age-old problems of signal filtration and desired feature extraction. This means that current signal processing algorithms are not able to interpret the electrical signals exhibited by neuronal synapses very efficiently, thus making such an interface wholly impractical and inaccurate. My project sought to rectify this through the creation of custom signal processing scenarios that utilized new algorithms; specifically, the use of Linear Discriminant Analysis and Vector quantization compression/extraction methods for enhanced noise filtration and the removal of known artifacts (sources of electricity other than the brain, such as muscles). However, I decided it was not enough to run software simulations; to determine its true real-world applicability, I used a 14- channel EEG neuroheadset to gather electrical data from my own brain. I then built a prototype robotic arm with an onboard processor that would translate signals from the computer. Finally, I used the programs I created to "decipher" the incoming brainwave signals, and send corresponding messages to the robotic limb. I concluded that, by using my programs to perform the signal processing, I was able to increase the accuracy of detected brainwave patterns by about 16%. Although this may not seem like much, the brain processes hundreds of thousands of ideas simultaneously, and recognizing patterns requires a great deal of processing effort on the part of the computer. Finally, I reached an accuracy of about 91.35% using the programs I created. --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- Further in-depth details can be seen here: Recently, after submitting my project, I was notified that I was one of the 60 semifinalists world-wide; as part of the judging process, there is also an award called the "People's Choice Award." Essentially, the public goes online and votes once in each of the 3 age groups (13-14, 15-16, 17-18) for the project they believe is the best. I am kindly asking if you would consider voting for my project for this award; I believe this project holds many potential applications in the real world other than prosthetics alone; such technology could be effectively utilized by patients with paraplegia, paralysis, or even polio. The voting process is simple: 1. Go the Google Science Fair Voting website: (for my project) 2. Click the "vote" button in the upper right-hand corner Again, thank you for your time and consideration of my project, Anand S

Topic by tech industries 

Solar Power Towers Efficiently Using Brayton Cycle

I want to point out a solar to electric generation concept that has yet to be seen anywhere, even though it originated back during the Carter Administration's ERDA programs of the late 70's. I’m talking about solar power towers that convert solar energy into electricity at the hundreds of mega-watt level. While power towers do exist today, and the world currently does have a handful of them as shown in Fig-1, none use the Brayton Cycle nor can they boast an energy conversion efficiency at the mid to upper thirty percent level.  A group of engineers got together at a think tank organization called Sanders Associates in Nashua, N.H., several decades ago, and designed a unique Brayton Cycle, 100 MW solar Power Tower concept for generating electricity. This was accomplished under ERDA (Energy Research Development Administration) who gave us a phase-2 follow-up contract that took our phase-1 design and built a working scale model at the 10 KW level. This model was tested at the Georgia Tech Solar Research Facility and "registered" ~37% electric solar conversion efficiency. The system used ambient air as its working fluid, and was to be located in open-spaced desert regions. Phase-2 was lost to competition using a closed-loop liquid sodium system that boiled water into superheated steam at 900F to run a turbine that generated ~21% overall electric conversion efficiency.  Apparently, at that time ERDA would rather haul water out to the desert than use ambient air to generate electricity? The politics of their decision is beyond reason and clashes with improving the world’s development of green technology energy.  ERDA shut out our better technological performer and safely locked it away for another day! ERDA's official reason for turning us down: "this technology uses excessively high temperatures (2500F versus 900F) that are dangerous to workman maintaining the equipment". But that was back in the 70’s, maybe we’ve learned to deal with high-temp heat by now?   Solar Energy Concept Using Low Pressure Storage Our solar power tower would collect the sun’s energy by locating its ceramic heat exchanger on top of a tall tower as shown in Fig-1. The tower was located in the center of a field of active sun-searching mirrors (heliostats, Figure-2). These mirrors reflected sunlight onto our ceramic honeycomb heat exchanger, producing a concentrated flux intensity level that heated it to around 2500F. At the same time, low pressure fans generating only a few psi pressure would suck the ambient air through the honeycomb, heating it to just under the 2500F and then passing it through energy storage silos which stored the heat down to ~150F. We purposely designed the energy storage charging phase of our hot air system to work at only a few psi above ambient as a safety feature. The sun effectively acts as the combustor of our jet engine or Brayton cycle engine. Once the sun heats the air, it passes through heat exchangers consisting of a labyrinth of underground silos that are temperature segregated. These silos receive our 2300F airflow and cool it down to about 150F, transferring this heat into solid salt containers which turn to liquid once they have absorbed sufficient heat. Figure-3 is a schematic of this underground energy storage facility and shows the airflow being heated by a fully charged set of silos containing liquid salt-bricks. This airflow direction is reversed when we charge the silo’s salt-bricks. The bricks are kept in specially insulated, high pressure silos (located underground for added insulation) that store the heat energy at one atmosphere for later use. These underground silos act as our energy storage batteries, and when needed would discharge their heat energy accordingly into the moving airflow. This energy storage concept permitted the generation of electricity at night and during overcast days. Two sets of storage systems are required for continuous operation. One would be charging at low pressure while the other is discharging at high pressure through the Brayton engine to generate electricity.   Electric Energy Generation at High Pressure Electricity would be created by turning an electric generator at high speed. The generator was turned by running a jet engine connected to it.  The engine’s combustor for heating the air is effectively the sun, hence the name Brayton cycle for generating our solar electricity (Figure-4). The heat from the molten salt containers would increase the energy of the high pressure air coming from the compressor, and would then force it through a typical turbine that turns this energy into high rotational speed to run the generator and make electricity. Our solar jet engine sucks in ambient air using its compressor, as all jet engines do, and blows it through a series of silos at high pressure whose stacked bricks are held at different temperature levels. We start our airflow through a silo held as low as 150F and work our way up to ~2300F as we pass through our last, hottest silo which acts to complete the effective solar combustion process. This air preheating technique dramatically improves our energy turnover capability and allowed us to convert solar energy into electricity at near 37% efficiency. During our electric energy generation phase, the silos of our Brayton system requires operating at many atmospheres of pressure just as in any jet engine combustor using petroleum-based JP-fuel.      

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500W electric scooter control and instrumentation with Arduino mega

1. Introduction DC 500W motor control with an Arduino mega to limit starting current and to vary the speed of the scooter. The battery is in 24V, 10A.h. The following table summarizes their characteristics: 2. Bibliography: Link download : sketch_escooter_feed_back_reel_V1.ino escooter_ampli_SIMULINK.mdl escooter feed back ISIS.DSN youtube  :  "study trotinette electric e-scooter 100W et 350W, wiring"  youtube;=75&list;=PLfZunVn_gcq7EOurXuWU2sRFmh6CbiUiL Article: «Study of electric scooters 100W and 500W (Arduino), Revue 3EI 2017» Pdf? Book «I realize my electric vehicle» at DUNOD 3. Open loop program To test the programming, we simulate the program in ISIS, as can be seen in the following figure. In addition, we have an LCD display to display data (duty cycle corresponding to the PWM at 32Khz, motor current, motor voltage, action on the pushbuttons, 4 push buttons are used. BP1 to manually increment the duty cycle, BP2 decrement it. BP3 set the duty cycle to 0, corresponding to the brake contact. The speed of the motor is practically proportional to the duty cycle We made our own current amplifier called a step-down chopper but it is possible to buy a shield There are many cards for Arduino to control DC motors especially of low powers and also of great powers as can be observed on the following links. But all these chopper shields measure the current internally but there is no current limitation. In order to have a current limitation, an analog current loop is required using specialized AOP or IC or a fast digital current loop. But what should be the value of the limitation current? The choice of the current value is normally for the 1-hour operation service in order to be able to carry out relatively long climbs without reaching the critical temperature of the engine. In our case, the limitation current must be Limiting motor = Power / Upper battery = 500W / 24V = 20A In addition, the power transistor of the chopper can only support 50A in our case. But in open loop, it has no current regulation, so as not to exceed the maximum current, a ramp of the duty cycle will be used. A 0.1 second interruption routine will be used to measure the voltage of the current (sample measurement, sample). This sampling time is arbitrary but does not allow to be faster than the rise time of the current because the electric time constant of the motor is L / R = 1.5 ms. Open loop operation with a 25.5s (8bit) ramp and 0.1s interrupt routine provides a good understanding of the operation of a DC motor drive. The display will only be done every 0.2s to have a stability of the digits on the screen. In addition, a digital filtering will be done on the current and the voltage on 4 values therefore on 0.4s. [b] Algo open loop [/b] Interrupt Routine All 0.1S Read voltage and current Loop loop (push button scan) If BP1 = 1 then increment PWM If BP2 = 1 then decrement PWM If BP3 = 1 then PWM = 0 Displaying variables every 0.2s Code: [Select] // include the library code: #include #include #include #define SERIAL_PORT_LOG_ENABLE 1 #define Led     13       // 13 for the yellow led on the map #define BP1     30       // 30 BP1 #define BP2     31       // 31 BP2           #define BP3     32       // 32 BP3 #define LEDV    33       // 33 led #define LEDJ    34       // 34 led #define LEDR    35       // 35 led #define relay   36       // 36 relay #define PWM10    10      //11   timer2    LiquidCrystal lcd(27, 28, 25, 24, 23, 22); // RS=12, Enable=11, D4=5, D5=4, D6= 3, D7=2, BPpoussoir=26 // Configuring variables unsigned   int UmoteurF = 0;  // variable to store the value coming from the sensor unsigned   int Umoteur = 0; unsigned   int Umoteur2 = 0; unsigned   int Umoteur3 = 0; unsigned   int Umoteur4 = 0; unsigned   int ImoteurF = 0;  unsigned   int Imoteur = 0; unsigned   int Imoteur2 = 0; unsigned   int Imoteur3 = 0; unsigned   int Imoteur4 = 0;            byte Rcy=0 ;    // 8bit duty cycle unsigned    int temps; // the setup function runs once when you press reset or power the board void setup() {   pinMode(Led, OUTPUT);   // Arduino card   pinMode(LEDV, OUTPUT);   pinMode(LEDR, OUTPUT);   pinMode(LEDJ, OUTPUT);   pinMode (PWM10,OUTPUT);     // Pin (10) output timer2   //  digitalWrite(LEDV,LOW);   Timer1.initialize(100000);         // initialize timer1, and set a 0,1 second period =>  100 000   Timer1.attachInterrupt(callback);  // attaches callback() as a timer overflow interrupt   lcd.begin(20, 4);    Serial1.begin(9600);   TCCR2B = (TCCR2B & 0b11111000) | 0x01;         //pin 10  32khz                                                   //   //   analogWriteResolution(bits) lcd.setCursor(0,1); lcd.print("Rcy"); lcd.setCursor(10,1); lcd.print("Um"); lcd.setCursor(5,1); lcd.print("Im"); lcd.setCursor(10,1); lcd.print("Um"); lcd.setCursor(20,1); // 4 lines display * 20 characters lcd.print("BP1+"); lcd.setCursor(25,1); lcd.print("BP2-"); lcd.setCursor(29,1); lcd.print("BP3=0"); } // Interruptions  tous les 0.1s void callback()  { temps++; //toogle state ledv for check   if ( digitalRead(LEDV)== 1 ) {digitalWrite(LEDV,LOW);}     else {digitalWrite(LEDV,HIGH);}     analogWrite(PWM10,Rcy);   // frequency Umoteur=analogRead(A0); Imoteur=analogRead(A1); Imoteur2=Imoteur; Imoteur3=Imoteur2; Imoteur4=Imoteur3; ImoteurF=(Imoteur4+Imoteur3+Imoteur2+Imoteur)/4 ; Umoteur2=Umoteur; Umoteur3=Umoteur2; Umoteur4=Umoteur3; UmoteurF=(Umoteur4+Umoteur3+Umoteur2+Umoteur)/4 ;   }// End routine // Loop corresponding to main function void loop() {    // BP + LED   if ((digitalRead(BP1))==1) {     lcd.setCursor(20,0);      // Column line     lcd.print("BP1");     digitalWrite(LEDR, LOW);        digitalWrite(LEDJ, LOW);     Rcy++;                        // PWM incrementation     if ( Rcy>254)  {Rcy=254;}     delay(100);               //8bits * 100ms = 25S increment 25ssecond slope     }        if ((digitalRead(BP2))==1) {     lcd.setCursor(20,0);     lcd.print("BP2");             Rcy--;      if ( Rcy<2)  {Rcy=2;}  // PWM almost at 0, engine stop         delay(100);      digitalWrite(LEDR, HIGH);     digitalWrite(LEDJ, HIGH);     }   if ((digitalRead(BP3))==1) {     lcd.setCursor(20,0);     lcd.print("BP3");      Rcy=2;               // PWM almost at 0, engine stop     } if (temps>=2)  { lcd.setCursor(0,0); lcd.print("                "); // Erase line lcd.setCursor(0,0);     lcd.print(Rcy); lcd.setCursor(5,0); ImoteurF=(ImoteurF)/20;     //resistance (5/1024)*(10/0.25ohm) si ACS712 66mV/A                            // For resistance 1ohm (ImoteurF) / 20; Simulation 5/25 lcd.print(ImoteurF); lcd.setCursor(10,0); UmoteurF=UmoteurF*10/38;                              //10/38   10/30 simula if (Umoteur>ImoteurF){UmoteurF=UmoteurF-ImoteurF;  }  //U-R*I lcd.print(UmoteurF); temps=0; }// End if time    } // End loop Since there is a limit of 9000 characters in the forum below Open loop program feature previous The interrupt routine lasts only 250 microseconds, the loop of the main program which scans the action of push buttons is 13micros and the display time of all data is 11ms. Thus, it is possible to improve the sampling period and thus the speed of the regulation of the current. The Arduino makes it possible to make the instrumentation of the scooter so to know the power, the consumption in Ah and Wh, to measure the speed, to know the consumption according to Wh / km, to measure the temperature of the engine, Have a safe operation. But for now we will see how to limit the current 4. Closed loop program, limited current control The sampling period will increase to 0.01 seconds (interrupt routine) If the current is less than the desired value, then the duty cycle can be increased or decreased to the desired value which is the setpoint. On the other hand, if the motor current is greater than the limiting value, there is a rapid decrease in the duty cycle. So as not to exceed the value of the duty cycle if it is saturated to 254 maximum and to the minimum value 6. Code: [Select] if (Imoteur<4000)                    // No current limitation at (20A * 10) * 20 = 4000   {if (consigne>Rcy)   {Rcy=Rcy+1;}   // Pwm ramp + 1 * 0.01second pure integrator    if (consigne    if ( Rcy>254)  {Rcy=254;}           // Limitation of duty cycle    analogWrite(PWM10,Rcy);   // Frequency 32kHz timer2}         } if (Imoteur>4000)  { Rcy=Rcy-5;              // No current filtering, to be faster                     if ( Rcy<6)  {Rcy=5;}       // Rcy is not signed, nor the PWM therefore Rcy minimum must not be less than 6                   analogWrite(PWM10,Rcy);   // Frequency 32kHz timer2}                        } 5. Closed Loop Program, Limited Current Control with Acceleration Handle An acceleration handle provides a 0.8V voltage when not operated and a 4.5V voltage when the handle is fully engaged. Instead of using pushbuttons to increase or decrease the speed setpoint, an acceleration handle will be used Code: [Select] Upoignee=analogRead(A3); // The relation in Upoign and the setpoint which corresponds to the duty cycle corresponds to if (Upoignee>100) { consigne=(Upoignee/2);     //0=a*200+b    et 255=a*800+b                      consigne= consigne-100;                   }                            else { consigne=0;   }               if (Upoignee<100) { consigne=0;  }     // redundancy     6. Temperature and safety program of the motor with the current measurement The outdoor temperature measurement can be easily performed by the LM35 component which charges 0.01V by degrees Celsius Code: [Select] temperature=analogRead(A2); //lm35 0.01V/°C temperature=temperature/2;       // Temperature coefficient lcd.setCursor(5,2); lcd.print("      "); lcd.setCursor(5,2); lcd.print(temperature);   // Display in ° C lcd.setCursor(9,2);      // Erasing secu display lcd.print("     ");   if (temperature>80 ) {lcd.setCursor(9,2);         // If motor external temperature is above 80 ° C                      lcd.print("secuT");                       Rcy=0;} In addition, thermal safety by measuring the motor current will be added. If the limitation current is greater than 10s then the motor will no longer be powered for 30s. A "secu" display will appear on the LCD display. This safety makes it possible to cut the motor on slope too high and when blocking the engine but it would be necessary to add the measurement of the speed in the latter case Code: [Select] if (timesecurite>=10000 ) {flagarret=1;      // If limitation current for a current of more than 10s                               timerepos=0;                               consigne=0;                               Rcy=0;                                 timesecurite=0;}       //   Then stop engine during a downtime    if (flagarret==1 ) {lcd.setCursor(9,2);         // If limiting current for a current of more than 20s                      lcd.print("secU");  }     //   Then stopping the motor for a stop time and display                                                     if (timerepos>=30000 &&  flagarret==1) {flagarret=0;                                           lcd.setCursor(9,2);      // After a rest time here of 30s                                            lcd.print("       ");   }   The display can be observed if the temperature is above 80 ° C Thermal safety by measuring the motor current (digital thermal relay) which allows to know the image of the internal temperature of the engine would be ideal. But for this, it is necessary to know well the thermal modeling of the motor. 7. Measurement of the energy capacity of the battery The energy capacity of a battery is in A.H, we will display the value in mA.H to have a high accuracy. The capacity will be in A.Second in the following equation. So to have in mA.H, it will be divided by capacity by3600. Capacity (A.s) n = I * Te + Cn-1 with Te = 0.01s and I multiplied by 10 So in the interrupt routine Code: [Select] capacity=ImoteurF+capacity ; And in the display Code: [Select] lcd.setCursor(0,3); // Display of energy capacity lcd.print("C mA.h="); capacity1=capacity/(18000);   //18000=3600*5  5=> Current measurement coefficient lcd.print(capacity1); To check a current of 10A with an adjustable resistor and after 30s, the capacity must be 83mA.H 8. Power and modeling with SIMULINK Modeling helps to understand the vehicle and its control. In addition, it is possible to compile the control part directly into the Arduino program from simulation under Simulink. But it will not be possible to simulate the instrumentation with the LCD display. In the following figure, we can observe the simulation of the programming of the chopper with the current limitation with Simulink. In the following figure, the green box shows the duty cycle control to vary the speed and the red border the current limitation. The controller of the control is here a simple integrator but it is possible to carry out a multitude of control. In the previous figure, it can be observed that the current is well limited to 25A from 2s to 9.5s. Then, the current reaches 10.8A under established speed regime at 22.5km / h. The dynamics are similar to the tests carried out. With a slope of 5%, the cyclic ratio reaches only 100% as can be seen in the following figure. The speed will reach painfully 19km / h with a current of 24A and a motor power of 580W. See article: Study of electric scooters 100W and 500W (Arduino), 9. First conclusion It is easy to control a 500W DC motor with an Arduino and some components So repair many scooters that are in DC motors. But it takes some knowledge (automatic, engine) to know how to properly manage the engine and limit its current so as not to damage it The display of the speed, the distance, the operating time to know the / km can also be realized with a menu 2. The .ino program as an attached file, But it is not possible to put an attached file in ISIS electronic labcenter? What is this forum? It would be desirable that the compiler could generate the.cof to debug in Isis and test the program line by line .... Arduino still has to make a lot of effort to be on the same level as other microcontrollers 10. speed measurement (tachometer) Velocity measurement is carried out using a hall effect sensor SS495 or A1324 which counts each revolution of the wheel. It is enough to enter the perimeter of the wheel of the scooter (130mm of radius therefore 0.816m in the case To have the speed, it is enough just to divide the number of turn of wheel on an arbitrary time of 1s to have a minimum speed of 0.81m / s therefore of 2.93 km / h. In addition, an average filter with 3 values will be used to display the speed. At 25km / h, there will be 8.5 laps. To count the turns, an external interrupt routine will be used on input INT0 21 of the mega card. To simulate the speed, a pulse on input 21 will be used with a duty cycle of 10%. Code: [Select] void INT0b21() {   Tspeed++;   // External interruption to count the number of turns } // In the set up declare the interrupt routine when the 5V edge of the magnet detection is done   attachInterrupt(digitalPinToInterrupt(21), INT0b21, RISING );  // External interruption // In loop if (temps09>=5)  {        // 1 second loop lcd.setCursor(13,2);      // Erasing speed lcd.print("kph     "); lcd.setCursor(16,2); speed1=Tspeed*2937;      //1tour*816*3.6/1s=2.937km/h speed2=speed1;           //Tspeed (rate/seconde) speed3=speed2; speedF=(speed1+speed2+speed3)/3000;   // To put in kph lcd.print(speedF,1);    // Display to the nearest tenth Tspeed=0;   // Reset counter temps09=0;  //reset time } To improve the accuracy of the velocity measurement, it is possible that the sampling time of the velocity measurement is dependent on the velocity. For example: For speeds less than 10km / h sample at 1second, but above 10km / h sample at 2 seconds. 11. Distance measurement for autonomy The distance corresponds to the total number of turns of the wheel multiplied by the perimeter of the wheel. So do not set the number of turns to 0 for each sample. On the other hand, the reset of the distance will be done when pressing the reset of the Arduino Mega. The distance display will be displayed to the nearest second. At 32km / h, it will take 2 minutes to do 1km as can be seen in the following figure: Code: [Select] void INT0b21() {   Tspeed++;   // External interruption to count speed   nbrRate++; } lcd.setCursor(13,4);      lcd.print("km      ");  // distance=(nbrRate*816)/1000;  //distance m distance=distance/1000;  //distance km lcd.setCursor(15,4);      lcd.print(distance,1);  You can observe the electrical installation with the chopper, the arduino, and the display when the program is set up 12. Synthesis The RAM space is used only at 4% and ROM space at 3%, for an Arduino mega. So we could take an arduino a little smaller. But, there are 8 Lipo cells to make the 24V power supply to power the engine via the chopper. Therefore, the voltage measurement of each element will be on the Arduino with a JST connector. This measurement makes it possible to know if a cell with an internal resistance which begins to pose a problem and to know if the balancing of each cell has indeed been carried out. It is possible to switch to 36V with 12 cells also with the arduino mega without using an external shield that multiplex 24 analog inputs on input A0 It is possible to send all data to a smartphone via Bluetooth HC06 via pins 20, 21, RX1 and TX1. But the application under android realized under JAVA Studio can not be shared on this forum. This part will not be explained. After having made the instrumentation of this scooter, a study should be carried out on the precision of the measurements, it is possible to read "Instrumentation of a low-power electrical motor vehicle" eco marathon "type Revue 3EI N ° 81, July 2015

Topic by Iutgeiisoissons