Pi Calculator?

Hello all. I was at school this one day, and I asked some stupid question about Pi to my math teacher. He eventually told the class about how, when he was in school, the school got a computer, and hired a programmer to program it to calculate Pi. And it just kept on spitting out numbers. And it never stopped. NEVER! So, he would come in and look every day to see if it had figured out Pi. And all through his schooling, it didnt. I was just wondering, first of all, how would you make a program that keeps on spitting out numbers (pi) and NEVER stops? I mean, I have yet to see anything that can actually keep on calculating and NEVER EVER stop. Secondly, is there a program (.exe) that will do that? Just a simple command window that spits out numbers.. 3.14159 is what i know.. and i dont know if thats ever right! :P Anyway, I basically want something like what I described. I will put it on this old laptop I have and let it run. Probably under my desk or something. So.. yeah. Now, REPLY!! :) THANKS! :) :D :P :D :) :D :P :)

Question by sci4me 7 years ago  |  last reply 5 years ago


Calculating Speed?

If you have an object with a mass of 2000 grams, and it has an average force of 635.029 kg pushing it for a distance of 6.096 meters before it becomes a free-flying projectile.  How fast is the object traveling after the 6 meters and how do you calculate it.

Question by jj.inc 6 years ago  |  last reply 6 years ago


Calculator IM

At my school we are required to have these TI-83 plus calculators for math. Of course we have classic games and stuff that we put on there, but we want to try to put an infrared emitter and detector on it so we could send IM's within the room to each other. Kinda like texting. Could anyone help us by suggesting ways to do this?

Topic by Jordo 11 years ago  |  last reply 9 years ago


LED calculator

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

Topic by mrshow555 11 years ago  |  last reply 8 years ago


Ultimately Simple Calculator

Listed in the Built By Monkeys blog from Design News, comes the ultimately simplistic calculator that anyone can use. It can be found At this location

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


TI Calculator Help

I have the TI-84 Plus Silver Edition and I have some questions. First I need to know how to graph the equation (x is greater than or equal to y) Also I put the quadratic program on my calculator but it gives the answer in decimal form, how do I view it in fraction form or is that even possible??

Topic by thouse 11 years ago  |  last reply 8 years ago


Calculator Programs for Math

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

Topic by sardines454 11 years ago  |  last reply 7 years ago


TI-connect for calculator

I'm having trouble loading "TI-connect" on my mac so that I can write programs for the ti-84 on the computer. After downloading ti-connect, I click on it, and it seems to want to install it again. I've done the complete loop, repeating the download process about 4 times.  Do any of you know what to do?

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


Stack Calculator (RPN)

Has any one made/have plans for making a stack calculator (reverse polish notation)? I kinda want to make one this summer so if no one else puts something up maybe I'll try to post something in the next couple months.Here is some info on RPN for anyone interested:http://en.wikipedia.org/wiki/Reverse_Polish_notation

Topic by hunt3131 10 years ago  |  last reply 10 years ago


Calculator data into a PC

I have a Check and Correct Calculator with 120 steps, I need to upload the data stored on the memory of the calculator, I mean the 120 steps all together into a excel file, or to a text file. Any ideas on how to convert a calculator into a small pad?

Topic by lmarkez 8 years ago  |  last reply 8 years ago


Diode Calculator will not work

I've been working on a diode only (well, plus switches for input [numbers, yet there's only one pad! not one for each digit], resistors for various things, and LEDs for the display) calculator that could add two two digit numbers (xx+xx=xxx) for a while, putting countless hours into it.I have deemed it impossible.There's so many problems with a mass diode resistor network that is just won't work. As some and gates conduct then some other gate (like it's suppose to) conducts, and eventually causes a voltage divder (with the pull up/ pull down resistors) and the output gets wacky and there's no wway of amplifying the signal.The diode adder is dead

Topic by guyfrom7up 10 years ago  |  last reply 10 years ago


555 Timer Calculator

Hi everyone, I was looking around on the internet a while ago for a calculator for 555 timer circuits and couldn't find one that worked very well. Then I set about making my own in a Excel spreadsheet to calculate the frequency and duty cycle for me. I have decided to share it with everyone to help others. It is quite simple. Enter your vaules into the yellow boxes and get your frequency and/or duty cycle from the blue boxes.

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


output wattage calculation?

Hey guys i have a 1100uf capacitor bank at 425V and the charge time is 30 sec does anyone know how to calculate the output wattage if the input voltage from the dc-dc converter is 12V at 3A ? thanks for all you answers :D

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


How to calculate resistance?

Ok, I need to figure out how to know what resistor to use. I know how to read a reistor, I just dont know how to use one. Say I hook an LED, a 9 volt battery, and a resistor in a circuit. I want to get the voltage down to 3 volts. How would I go about calculating a resistor reading? What ohm resistor would I use? How do I know?

Question by Adum24 8 years ago  |  last reply 8 years ago


Simple Torque Calculation!

Hello! I want to calculate the torque for my project.I will have 4 individual motors to move a vehicle around 10kg. Here’s the specs:Wheel weight = 100g Wheel radius = 3” Wheel axis radius = 2” Vehicle weight = 10kg Speed I want to reach = at least 20mph with ease.Because I’m using four motors, I’m assuming torque needed would also be 1/4 of total torque needed to move the vehicle.Thank you! I appreciate any help!

Question by TylerK84 1 year ago


Cheap calculator hack

I put together a Solarbiotics Magbot Pendulum and it has a period of one second. I measured this by using a stopwatch and counting the swings for five minutes. . What I would like to do is count the number of times it swings back and forth over an extended period of time, for example 24 hours.   I came across an article showing how to use a cheap calculator to count the number of turns a shaft makes. A cam attached to the shaft presses the "+" key each time the shaft turns one full turn. to use it, you clear the calculator and press the "1" button. Then every turn the cam presses the "+" button and 1 is added to the sum being displayed. Every cycle of the pendulum causes the LED to flash (pulse)  once. I'd like to use these pulses to do the electronic equivalent of pressing the "+" button.  It might be possible to count these pulses using electronic circuitry (decade counters) but electronic calculators only cost about a dollar of two and I'd like to give that a try. Any suggestions would be appreciated.

Topic by dickb24 5 years ago  |  last reply 5 years ago


Cheap calculator hacking

I put together a Solarbiotics Magbot Pendulum and it has a period of one second. I measured this by using a stopwatch and counting the swings for five minutes. . What I would like to do is count the number of times it swings back and forth over an extended period of time, for example 24 hours.   I came across an article showing how to use a cheap calculator to count the number of turns a shaft makes. A cam attached to the shaft presses the "+" key each time the shaft turns one full turn. to use it, you clear the calculator and press the "1" button. Then every turn the cam presses the "+" button and 1 is added to the sum being displayed. Every cycle of the pendulum causes the LED to flash (pulse)  once. I'd like to use these pulses to do the electronic equivalent of pressing the "+" button.  It might be possible to count these pulses using electronic circuitry (decade counters) but electronic calculators only cost about a dollar of two and I'd like to give that a try. Any suggestions would be appreciated.

Topic by koyescha 5 years ago  |  last reply 5 years ago


K'Nex Computer & Calculators!

Check it out: some students Olin College have been building calculating devices entirely out of K'Nex! These are totally fantastic old-school devices, ball-powered. My inner geek is having fits of joy.Check out some pictures of their stuff here.Unfortunately they don't have complete instructions up! They should definitely post the whole thing on Instructables- I sent Matt a message earlier today. If you want to see his project on the site, drop Matt an email and tell him he should post the directions on Instructables! His contact info is here.

Topic by canida 11 years ago  |  last reply 8 years ago


Gravity Lamp Calculations

Http://www.core77.com/competitions/greenergadgets/projects/4306/ some people might recognize this little invention a while ago.  Well I recently wanted to make one after a freak snow storm rocked central pennsylvania (didn't have power for 2 days, it sucked balls).  But, after doing the math, his claims seem impossible.  Someone check the math for me: Facts of the Gravity lamp (with data in favor of the lamp_: output: 600 lumens weight falling: 50 pounds distance falling: 58 inches (in reality it's a bit shorter, but i'm just putting everything in favor) for ease of calculation and in favor of the lamp, assuming 100% efficiency. lasts for 4 hours calculations: 600 lumens = 7542 candellas = 7542000 mcd the highest efficient LEDs i could find output 120,000mcd at 20mA (0.02 amps) with a drop of 3.2 volts 7542000mcd/120000mcd = 63 LEDs 1 LED = 3.2 volts * 0.02 amps = 0.064 watts 63 LEDs = 4 watts 50 pounds = 22.68 kg on earth: the force of the weight is 22.68*9.8 = 222.264 newtons 58 inches = 1.47 meters 1 joule = 1 watt * 1 second = 1 newton * 1 meter 222.264 newtons * 1.47 meters = 326.73 joules 326.73 joules / 4 watts = 81 seconds, NOT 4 hours looking back at it, I think i messed up the calculations at earth's gravity, because that part is just totally wrong :P.  I'm not far enough into my physics class to know how to properly calculate that, could someone else?

Topic by guyfrom7up 9 years ago  |  last reply 9 years ago


Calculating heating effect.? Answered

I have been experimenting with making a hot wire foam cutter. This needs to be at least 600 mm wide. I have to hand a PSU capable of providing 14 volts at 2 amps (or slightly below) This is 28 watts. Now the question i would like to calculate the heat the Nichrome wire will reach at any given wattage but have no idea if I can do this. I have several wires that work to different levels, resistance of 30R, 4 R, 137R at the length I am using. Any one any  ideas how to calculate the temp or are there too many variables? So far I have worked empirically and arrived at the conclusion I need either around 18 volts at about 3 amps or I need a wire with a resistance of around 7R to suite the power i have available. I do know that the 20+ watts I am generating is just heating the wire to the melting point of the polystyrene foam. The melting point of the foam is apparently around 220 to 240 deg C (internet) At present it isn't cutting fast enough for my project. which required producing 5 mm thick sheets of foam with a reasonable consistency. i am cutting them from a 50 mm thick 1000mm x 500 mm block.

Question by rickharris 5 years ago  |  last reply 5 years ago


How to Calculate Viewership

As the statistics page on Instructables has never been particularly reliable, I have used an alternate method to check my viewership for some time. As other people have expressed interest in statistics, I've decided to share how I do it. Overall viewership between two points in time To use this method, you will need to have taken a snapshot of your member page and have logged it into the Internet Archive or recorded the number of views you have attained at a previous date. Compare the number of views between the two dates to figure out the number of views that have occurred during the period between the two recordings. To find average daily views Using the date from the Internet Archive snapshot or your own records, use this to calculate the number of days that have elapsed since the previous entry to find the number of days that have transpired. Divide the difference in viewership between the two dates by the number of days that have gone by to find your average overall daily viewership. To find the average daily views of your instructables Perform the above steps and divide the number of daily views by the number of instructables you have posted. ----------------------------------------- As with most statistics, the figures you will see from these calculations can be skewed. However, they are still good for getting a good general handle on what the situation is for you as far as viewership goes. If you have not used Internet Archive beforehand, it is a harmless way to log this information as well as take a screenshot of something that you and others can look back on at a later date. Statistical use is only one of many this sort of thing can be used for.

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


Calculating amperage and wattage?

So I'm doing an energy inventory on our house to see how much electricity we use, and maybe see if we could cut down on some costs.  Being Christmas right now, we have a long multi-string chain of lights going across our living room. I'd say it's about 50 feet long. They are just regular incandescent lights. typical normal size, no LEDs or flashers or anything. When you plug them in, they come on, and that's all they do. I wanted to figure out their wattage, so I started with finding the amperage. My multimeter isn't very good when it comes to measuring amps, so I decided to use a roundabout method by finding the resistance of the circuit. The resistance came out to be 13.3 ohms. Plug that into ohm's law and you get around 9 amps of current and therefor, about 1080 watts of electricity. That sounded right to me...after all, it is a long string of lights, and even though they don't individually suck up a lot, I figured it adds up.  I tried this same method with a single bulb that I knew to be around 300 watts. The resistance came out to be about 4.5 ohms giving a whopping 26.7 amps with a wattage of around 3200 watts! That can't be right. I want to know what I'm doing wrong. I'm pretty sure it can't be my multimeter because I just bought it brand new about a month ago. What am I doing wrong?

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


A advanced Arduino calculator?

So I thought about a new project: make an "advanced" calculator since online there are plenty of tutorials of simple ones. I have done already the circuit and I have only some problems with the code since this is only my third project on Arduino and I don't  know programming in C. So basically: when I switch on the device it shows me a long text which I can scroll using a pair of pushbuttons(when the text can't scroll anymore a led switches on). When I push them contemporanealy the device switches to calculator. And this is the code I made (I know there are plenty of errors): #include #include long num1,num2 ; double total; char operation,button; const byte ROWS = 4; const byte COLS = 4; char keys[ROWS][COLS] = {   {'1','2','3','+'},   {'4','5','6','-'},   {'7','8','9','*'},   {'C','0','=','/'} }; byte rowPins[ROWS] = {A0,A1,A2,A3}; //connect to the row pinouts of the keypad byte colPins[COLS] = {A4,A5,0,1}; //connect to the column pinouts of the keypad Keypad customKeypad = Keypad( makeKeymap(keys), rowPins, colPins, ROWS, COLS); // === CONSTANTS AND GLOBALS === // -- PINS -- const int PIN_LCD_LED = 6;  // analog const int PIN_ERR_LED = 7;  // digital const int PIN_BUTTON1 = 8;  // digital const int PIN_BUTTON2 = 9;  // digital // -- LCD -- // PIN 12   -> RS // PIN 11   -> Enable // PINS 2-5 -> D4-7 LiquidCrystal lcd(12, 11, 2, 3, 4, 5); // number of columns in the LCD const int LCD_COLS = 16; // LCD brightness [0, 255] const int LCD_BRIGHTNESS = 128; // LCD ON or OFF int state_lcd = LOW; // start position for text int lcd_start = 0; // -- LED -- // LOW -> LED is OFF - HIGH -> LED is ON int state_led = LOW; // stores time when turned LED on unsigned long t0_led; // timeout to turn the LED off const int LED_TIMEOUT = 500; // -- text to print -- // ASSUMPTION: text always longer than LCD_COLS, if not add a check in loop const char TEXT[] = "After trying Helloworld I made this more advanced version..."; const int TEXT_LEN = (sizeof(TEXT) / sizeof(char)) - 1; const int LCD_LIMIT = TEXT_LEN - LCD_COLS; // === CONSTANTS AND GLOBALS END === // === INITIALIZATION === void setup() {   // -- SET DIGITAL PINS --   pinMode(PIN_BUTTON1, INPUT);   pinMode(PIN_BUTTON2, INPUT);   pinMode(PIN_ERR_LED, OUTPUT);   // -- SET UP LCD --   lcd.begin(16,2);   lcd.noDisplay();   digitalWrite(PIN_LCD_LED, state_lcd);   // ERROR LED is off when starting   digitalWrite(PIN_ERR_LED, state_led);   // -- read buttons --   int state_button1 = digitalRead(PIN_BUTTON1);   int state_button2 = digitalRead(PIN_BUTTON2);     // pushed button 1 -> try to scroll left or turn LED on if can't     if(HIGH == state_button1)     {       if(lcd_start > 0)       {         lcd_start--;         state_led = LOW;         digitalWrite(PIN_ERR_LED, state_led);         delay(200);       }       else       {         state_led = HIGH;         digitalWrite(PIN_ERR_LED, state_led);         t0_led = millis();       }     }     // pushed button 2 -> try to scroll right or turn LED on if can't     if(HIGH == state_button2)     {       if(lcd_start < LCD_LIMIT)       {         lcd_start++;         state_led = LOW;         digitalWrite(PIN_ERR_LED, state_led);         delay(200);       }       else       {         state_led = HIGH;         digitalWrite(PIN_ERR_LED, state_led);         t0_led = millis();       }     }     // -- print text on the LCD --     for(int i = 0; i < LCD_COLS; i++)     {       lcd.setCursor(i, 0);       lcd.print(TEXT[lcd_start + i]);     }     // ERROR LED is ON     if(HIGH == state_led)     {       unsigned long td = millis() - t0_led;       // LED has been ON for more than LED_TIMEOUT ms. -> turn it OFF       if(td > LED_TIMEOUT)       {         state_led = LOW;         digitalWrite(PIN_ERR_LED, state_led);       }     }   }   // normally 20FPS   // === INITIALIZATION END === // === MAIN LOOP === void loop() {   // == LCD STILL OFF ==   if(HIGH == state_lcd)   {     // pushing both buttons -> turn LCD on     int state_button1 = digitalRead(PIN_BUTTON1);     int state_button2 = digitalRead(PIN_BUTTON2);         if(HIGH == state_button1 && HIGH == state_button2)     {       analogWrite(PIN_LCD_LED, LCD_BRIGHTNESS);       lcd.display();       state_lcd = HIGH;       delay(250);     }   }     else  // == LCD ON ==   {     // Loops are convenient for reading key press from keypad     while(1) // First loop. Here we read keypad and compose our first number. It does so untill we press operation button and break's out of loop or 'C' and it starts from beginning of this loop     {                 button = customKeypad.getKey(); // Button read         if (button=='C') // If user wants to resset while he is writing first number         {           num1=0;           num2=0;           total=0;           operation=0;           lcd.clear();         }                 if (button >='0' && button <='9') // If user pressed numeric value, 1 character at a time.         {           num1 = num1*10 + (button -'0'); // Our numeric values are 0-9 witch means they are in first decade, when we multiply with 10 we basicaly add zero after number,           // than we add a new number entered to that zero spot. As for (button -'0') this is simple ASCII table "trick" 0...9 in ASCII table are 48 ... 57,           // so by subtracting '0' from any of them we get their value in decade system ex. char '5' = 53 in decade numeric system minus 48 for zero char gives us value of actual 5,           // if our previous number was ex. 25 we get 250 by multiplying it with 10 and then we add 5 and we get 255 witch gets printed on LCD.           lcd.setCursor(0,0); // Select first row on lcd           lcd.print(num1); // Print current number1         }         if (num1 !=0 && (button=='-' || button=='+' || button=='*' || button=='/')) // If user is done inputing numbers         {           operation = button; // operation remembers what mathematical operation user wants on numbers           lcd.setCursor(0,1); // set cursor to row 2           lcd.print(operation); // print our operator           break;         }     }         while(1) // Second while loop, it loops untill user has pressed '=' or 'C'. so it either prints total or ressets program     {         if (button =='C'){break;} // This covers case where user pressed operator and still wants to reset         button = customKeypad.getKey();         if (button=='C') // Making sure user wants to reset at anytime         {           num1=0;           num2=0;           total=0;           operation=0;           lcd.clear();           break;         }         if (button >='0' && button <='9') // Getting chars from keypad for number 2         {           num2 = num2*10 + (button -'0');           lcd.setCursor(1,1);           lcd.print(num2);         }         if (button == '=' && num2 !=0)// If button pressed was '=' its the end of the road. Calls domath() subroutine does calculation and print our results         {           domath();                              break;          }     }     while(1)     {       // After all is done this loop waits for 'C' key to be pressed so it can reset program and start over.       if (button =='C'){break;} // This line is side effect of previous loop since if user pressed 'C' it breaks out of previous loop and continues here.So we need to break this one aswell or user would need to press 'C' 2 times       button = customKeypad.getKey();       if (button =='C')         {            lcd.clear();            lcd.setCursor(0,0);            num1=0;            num2=0;            total=0;            operation=0;            break;         }     } } void domath() // Simple switch case to pick what operation to do, based on button pressed by user. {   switch(operation)     {       case '+': // Addition           total = num1+num2;           break;             case '-': // Subtraction           total = num1-num2;           break;             case '/': // Division. Could add error for division by zero, or change line in second loop where it waits for '=' char to if (button == '=' && num2 != 0) this will halt program untill num2 is not zero and then continue           total = (float)num1/(float)num2;           break;             case '*': // Multiplication           total = num1*num2;           break;               }     // Based on case selected print our total and     lcd.setCursor(0,1);     lcd.print('=');     lcd.setCursor(1,1);     lcd.print(total);       } } // === MAIN LOOP END === Waiting your answers, Cristian

Question by IlirD2 2 years ago  |  last reply 2 years ago


What to do with pocket calculator insides?

What should I do with my calculator insides? The calculator wwas shaped like a ruler and it has an LCD screen, a circuitborad, a battery, some wires and a solar cell, but I have no idea what to do with it.

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


i want to modify my casio 991ms scientific calculator so that it can store text files .. plzz any one can help me??

I  want to modify my casio 991ms scientific calculator so that it can store tex files ..i think a external memory card and prorgramming will do tthis plzz any one can help me??

Question by nmittal707 7 years ago  |  last reply 7 years ago


how do i save my research in my profile?

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


how can i view all step on one page?

Question by elein 8 years ago  |  last reply 7 years ago


TI-83 Buttons not working

On my TI-83, the bottom two rows of keys do not work. I took it apart an did the 'Contact Cleaner' but still no luck. Actually, the bottom rows and the 'trace' 'graph' and 'arrow' buttons do not work. Do I have to replace the entire board?

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


My project X My Car = Lumber

Not sure where to post this but figured I'd at least got the right website. I drive a Scion xB (aka the angry toaster) so I know what lumber I can carry. I'm looking for a calculator that I can tell the number of pieces, their dimensions and what the max of my car is capable of and receive the number of different pieces of lumber I can should buy to complete the project. Does such a thing exist? The math and algorithm is relatively simple. I'm just to drunk to work it out at present and it'd be a site well worth having in my bookmarks. If you know of a site this is a quick post, if not what would you like to see in such a site? Example: Building drawers for my small work space (13' x 6')  the structure I've come up with to support the drawers requires a frame of  2x4's: 3x sides: 2x56" 3x7" cross members: 4x 25" 2x 54.5 How many 2x4's should I buy if the max length of 2x4 I can fit is 8'? (I love my scion xB) 

Topic by MichaelD158 3 years ago  |  last reply 3 years ago


any good codes for a simple calculator? Answered

I wanna impress my friends with some cool calculator trick, unfortunately I no nothing about programming. Any body now' a good code ?

Question by Quest for Questions 8 years ago  |  last reply 8 years ago


My calculator needs to become pretty!

I have this big ugly calculator and i really want to make it look really awesome... do any of you wonderful people know how i could do so? I would like to just give it a design or something- no sparkles or beadazzles. Thank you!:D

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


Calculator Hacking, i need some Instructables. :(

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


Can solar powered calculators charge a phone?

I was just wondering because if this is possible I want to know how to do it. I can get a lot of solar powered calculators....They're cheap.

Question by Tech-Monkey 6 years ago  |  last reply 6 years ago



How do i make a program for normal curve?

My prob and stat class has this assignment due in a month and its to be able to make a program for Normal Curve..Can anyone help me with this? I've spent the last 3 days trying to figure it out but I can't.

Question by MathMan371 7 years ago  |  last reply 7 years ago


Replace calculator ink roller?

How to remove and replace ink roller in Sharp 1197S desk printing calculator

Question by Julia Anne 9 years ago


Resistance calculator using flash

I just created a resistance calculator using liveswif (its like macromedia flash only not as good) and programmed it with actionscript.   I can't figure out how to get the numbers to line up properly, although the calculator still works.   If you have a resistor and need to find out how many ohms it is, the calculator will do it.   http://www.gamesfree4u.com/resistancecalculator.html

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


Help with resistor calculator for LEDs

Hi everyone, I decided to try and build some LED lighting and found a few online resistor calculators but, I'm not exactly sure what to put for the voltage drop and the LED current (other than using the generic suggestions from the online calculators). So here are my questions... Is the "forward voltage" what you enter for the "voltage drop"? If so, do you use the lower or higher number? For the LED current, do I use the "max cont. foward current" or should I just put in the suggested 20mA? what kind of a difference would one be over the other? These are the specs given for the LED I'm going to be using (minus the unimportant stuff). Forward Voltage (V) : 3.2 ~ 3.8 Reverse Current (uA) : <=30 Absolute Maximum Ratings (Ta=25°C) Max Power Dissipation : 80mw Max Continuous Forward Current : 30mA Max Peak Forward Current : 75mA Reverse Voltage : 5~6V Thanks in advance.

Topic by GSXR 8 years ago  |  last reply 8 years ago


Conical coil inductance calculation? Answered

Does anyone know a reliable calculation or online calculator for conical coil inductance? I am calculating this for a Tesla coil primary if anyone knows is a conical coil primary suitable for a 2000W system?

Question by The MadScientist 8 years ago  |  last reply 8 years ago


How to calculate trajectory of projectile? Answered

How would I calculate the trajectory of a projectile with only the weight of the projectile, the velocity of the projectile at barrel, and angle of the barrel?  How did the artillery operators during WWII know how much powder to put or the angle of the barrel? Thanks for any help

Question by electronicz 5 years ago  |  last reply 5 years ago


how to calculate battery current ?

i want to make a ps2 battery, but it is must be up to 5.65 A

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


Calculating my DC motor

I'm not sure on how to calculate the things I need. Please help!!!!Pulley Radius- 5.85mmMass(load)- 0.2334 kgVolts- 9VCurrent- 0.096ASpeed-112.4rpmForce-?Torque-? Power-?Power Out -?Efficiency- ?

Topic by hj212121 7 days ago  |  last reply 7 days ago


Astable transistor component calculation Answered

Greeting AllI made a few astable and monostable circuits. The one in the attached picture gives me an output of about 1 second, but i need to know which RC components i need to make it give a mark space ratio of 6 seconds.I'd appreciate if i can get the answer along with the calculation and an explanation of how to do the calculation.Thanks in advance for any assistance.KRGK

Question by GhengisKhan1981 1 year ago  |  last reply 1 year ago


Calculating notes of twanged strips Answered

Consider a twanged metal ruler, or the "keys" of a thumb piano (kalimba)... I'm in the middle of designing A Thing, and I am sure that there ought to be a way of calculating the note produced when you twang the end of a strip of metal. Assuming I know the Young's modulus, length, width & thickness of a strip of metal (rectangular cross-section), is there a formula into which I can plug these numbers and predict the note produced? Or are there other properties I need to know?

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


calculating MAX7219 resistor value?

I want to use the 7219 to drive two 3digit 7segment displays with these specs. I want to use 1.85v and 18mA. Here's what the MAX7219 datasheet states as resistor values to be used. I'm too dumb to figure out how the resistor value is calculated. Can someone help? What would the resistor value be for 1.85v 18mA?

Question by DELETED_MakiY2 1 year ago  |  last reply 1 year ago


Best IC Calculator Question

I am looking for a chip just like the ones used in any calculator that does multiplication addition and subtraction. THe device i am looking to build has to be as thin as a credit card have a 8 character segment lcd and only be able to do addition and subtraction. so i need to be able to have buttons" 1 to 0 + - and = and . "nothing more. i looked at some attiny ics but they require a another ic to drive the lcd. also the the data entered need to stay in if the power of the ic goes out. most calculators have only one ic, any idea what the best ic for this application will be? thank you in advance. i need something this small. http://www.logopremiums.com/calculator-ballpoint-pen-HWK922LP.jpg Thank you

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


calculating yardage bench cushions?

I have four slabs of foam about 3" thick,  each: L 32 5/8" X W 14 5/8"  I plan to sew  box-type cushion slip-covers for each. How much yardage should I buy? I figure I should add about an extra yard for errors? Any advice in this regard would be greatly appreciated. blessings

Question by seth310 9 years ago  |  last reply 9 years ago


How are ratings (stars) calculated? Answered

How are the ratings calculated?  I used to assume that the number of stars an instructable had was an average of all of the ratings other readers had rated it.  But there have been two times that I was the first to rate and rated a terrible 'ible with a half star (one was just worthless and one deserved negative stars for being really bad advice) and it gets posted as "3.68 stars - your rating 0.5 stars".    When I rated a new 'ible as a 4, it came up as a 4.

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


Calculate magnet repulsive force?

I'm looking to make a "floating" model by insetting NdFeB rare-earth magnets with same poles facing so they repel. Now, magnet selling places specify the "pull" a magnet might have, say 1.2kg. What I would like to know is if the repel is equal in magnitude as the pull if two similar magnets are placed with same poles facing, is the force exerted 1.2kg and so I could float 1.2kg of stuff? Also, does stacking magnets double the attractive or repelling force, i.e. do two 1.2kg magnets stuck together lift 2.4kg of stuff, negating the small difference in distance of one magnet from the object? Is there a way to calculate the distance between two opposing magnets with a force applied. Does it follow the inverse cube rule? And if the stacking does work, do I also need an equal number of magnets on the other side for repelling, i.e. a stack of two 1.2kg magnets repels 2.4kg with one 1.2kg on the other side, or not? Does the magnet on the other side have to be the same force? Lots of questions but hoping someone can shed some light on this as I've not been able to find anything about it :-(

Topic by chiok 10 years ago  |  last reply 3 years ago


Resistor Calculator for electronic enthusiasts

Hi to evebody. I would like to share a tool which was developed for my own needs. For some time I recently need to obtain not standard resistor values with rationed precision from standard E24 series of resistors. Unfortuantely I don't find really good and convenient tool to do it. Finally I decided to made Resistors Finder for iPhone. I did my best to create simple, nice and convenient user interface and fast searching algorithm. Resistor Finder was just released yesterday on App Store. If you want a  free copy please PM me for promo code. Only 10 promo codes available. It will be nice to hear some feedback from you all. Any suggestion, critics and feature requests are welcome.

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