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271  Using Arduino / Project Guidance / Re: Control PC power with arduino on: November 29, 2012, 07:26:54 am
Thnx, I'm total noob in electronics I suppose that the easiest thing you be just use another relay which will be set to ON state when the power adapter is on and I will just read state of the relay using one of arduino PINs ?
You probably don't want a relay, since those are fairly slow acting, but an optocoupler is essentially a relay.
I don't mind about the speed as that relay will just be used to inform arduino that power adapter was trunde off, but optocoupler looks as more natural solution - as I said I'm total
noob in electronics so wish me luck !

I relation to distinguishing between power sources I found interesting article here:

So as I can understand I can measure the voltage of the power source, assuming that USB power voltage is about 5V and I will use external power adapter producing 12V I should be able to use "SecretVoltmeter" approach to recognise which power source is currently connected ? Do you think that would work ?
You can't use SecretVoltmeter , it measure the voltage of the AVcc, which in both case all 5V.
272  Using Arduino / Project Guidance / Re: Lighting Lots of 1.2v Bulbs...or Bright LEDs on: October 16, 2012, 09:50:12 am
If you use LEDs, you may try Charlieplexing
With 6 Pins you can control 30 LEDs.
273  Using Arduino / Project Guidance / Re: Okay, how do I control a PC fan with the LCD screen ie faster or slower? on: September 23, 2012, 05:19:10 am
You can read this A Complete Beginners Guide to the Arduino. to learn how to connect the push button in Project 4.
274  Using Arduino / Project Guidance / Re: 5v down to 3.3v for 3.3v sensitive devices on: August 09, 2012, 05:36:12 pm
May be you can did it yourself without waiting for stock.
275  Using Arduino / Project Guidance / Re: Hi, My fading PWM Leds aren't fading the way they should be... on: July 03, 2012, 07:39:08 am
The way you used to correct the negative value was incorrect, you can't any value less then 128,
try this code

    // set the colours and correct for negativity 
  int RedValue = (raw.XAxis>0?raw.XAxis:((raw.XAxis+256)/2)) ;
  int GreenValue = (raw.YAxis>0?raw.YAxis:((raw.YAxis+256)/2)) ;
  int BlueValue = (raw.ZAxis>0?raw.ZAxis:((raw.ZAxis+256)/2) ;
276  Using Arduino / Project Guidance / Re: volatage regulation on: July 02, 2012, 06:41:15 am
Here are some of the links

Voltage Boosters
A simple regulated DC-DC booster for up to 60V 1/4W. It uses no special ICs, just basic
components and two pins from the Arduino.

Buck–boost converter

Single-ended primary-inductor converter

Switch Mode Power Supplies

Design of Switch Mode Power Supplies

A New Approach for High Efficiency Buck-Boost
DC/DC Converters Using Series Compensation

AVR450: Battery Charger for SLA, NiCd, NiMH and Li-Ion Batteries

Voltage boost and buck circuits using Atmel AVR Tiny13V for driving a white LED.

277  Using Arduino / Project Guidance / Re: Knight rider light bar with lcd bar graph on: June 30, 2012, 10:40:24 pm
SSD1306 from is not LCD that used in LiquidCrystal Libraries which using HD44780.

You can download our SSD1306 OLED display Arduino library from github
and follow the example
278  Using Arduino / Project Guidance / Re: Knight rider light bar with lcd bar graph on: June 30, 2012, 08:19:35 pm
Here are example of the merge code.
#include <LiquidCrystal.h>
#include <LcdBarGraph.h>

The circuit:
 * LCD RS pin to digital pin 13
 * LCD Enable pin to digital pin 12
 * LCD D4 pin to digital pin 11
 * LCD D5 pin to digital pin 10
 * LCD D6 pin to digital pin 9
 * LCD D7 pin to digital pin 8
 * LCD R/W pin to ground
 * 10K resistor:
 * ends to +5V and ground
 * wiper to LCD VO pin (pin 3)

byte lcdNumCols = 16; // -- number of columns in the LCD
// byte sensorPin = 0; // -- value for this example
int sensorPin = A0; // select the input pin for the potentiometer
//int ledPin = 13; // select the pin for the LED
int sensorValue = 0; // variable to store the value coming from the sensor

LiquidCrystal lcd(13, 12, 11, 10, 9, 8); // -- creating LCD instance
LcdBarGraph lbg(&lcd, lcdNumCols);  // -- creating

void setup(){
  // -- initializing the LCD
  lcd.begin(2, lcdNumCols);
  // -- do some delay: some time I've got broken visualization
pinMode(6, OUTPUT);
pinMode(5, OUTPUT);
pinMode(4, OUTPUT);
pinMode(3, OUTPUT);
pinMode(2, OUTPUT);
pinMode(1, OUTPUT);
pinMode(0, OUTPUT);


void loop()
  // -- draw bar graph from the analog value readed
  lbg.drawValue( analogRead(sensorPin), 1024);
  // -- do some delay: frequent draw may cause broken visualization
sensorValue = analogRead(sensorPin);
digitalWrite(3, HIGH);
sensorValue = analogRead(sensorPin);
digitalWrite(3, LOW);
digitalWrite(4, HIGH);
digitalWrite(2, HIGH);
sensorValue = analogRead(sensorPin);
digitalWrite(4, LOW);
digitalWrite(2, LOW);
digitalWrite(5, HIGH);
digitalWrite(1, HIGH);
sensorValue = analogRead(sensorPin);
digitalWrite(5, LOW);
digitalWrite(1, LOW);
digitalWrite(6, HIGH);
digitalWrite(0, HIGH);
sensorValue = analogRead(sensorPin);
digitalWrite(6, LOW);
digitalWrite(0, LOW);
digitalWrite(1, HIGH);
digitalWrite(5, HIGH);
sensorValue = analogRead(sensorPin);
digitalWrite(1, LOW);
digitalWrite(5, LOW);
digitalWrite(2, HIGH);
digitalWrite(4, HIGH);
sensorValue = analogRead(sensorPin);
digitalWrite(2, LOW);
digitalWrite(4, LOW);
279  Using Arduino / Project Guidance / Re: Self power control using a battery, voltage regulator and transistor on: June 12, 2012, 09:53:11 am
How do you connect the collector of the transistor?
For AVR to control the transistor, the emitter had to connected to ground or 0V of the AVR, then how you control the supply to the AVR?
280  Using Arduino / Project Guidance / Re: Control speed and direction of a DC motor on: June 06, 2012, 07:43:01 am
This link to a motor driver with relay and PWM. It need a single DPDT relay, a single power MOSFET for the PWM and 3 bipolars for each motor. Motor supply need to higher then 10V or you will need to change the MOSFET to logic level gate MOSFET.
281  General Category / General Discussion / Re: Sinclair Spectrum 30 years old on: May 16, 2012, 09:29:32 pm
My first PC was Sinclair zx81 using Z80 CPU, I had also the 16K RAM expansion module

The set still keep in my store room and not like this
282  Using Arduino / Microcontrollers / Re: Uploading to LM324 on: April 23, 2012, 08:06:51 am
How-To: Shrinkify Your Arduino Projects

It using 8 pin ATtiny45 or ATtiny85 chips.
It using the Arduino code and IDE.
283  Using Arduino / Project Guidance / Re: How do I take Output of Ultrasonic sensor to Input to 16x2 LCD TM162A on: April 16, 2012, 08:29:34 am
Have you try this tutorial for your LCD
284  Using Arduino / Project Guidance / Re: Help in programming! on: April 10, 2012, 05:27:34 am

//Arduino PWM Speed Control:
int E1 = 6;   
int M1 = 7;
int E2 = 5;                         
int M2 = 4;                           
void setup()
    pinMode(M1, OUTPUT);   
    pinMode(M2, OUTPUT);
void loop()
  int value;
  for(value = 0 ; value <= 255; value+=5)
    digitalWrite(M2, HIGH);       
    analogWrite(E1, value);   //PWM Speed Control
    analogWrite(E2, value);   //PWM Speed Control
285  Using Arduino / Sensors / Re: How to make a coin selector for Making a piggy bank? on: April 06, 2012, 05:48:18 am
All that it looks at is the diameter of the coin.

Using Eddy Current coin detector,97925.0.html
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