Hi!
I am trying to use a transistor to turn power on/off for a dc motor (not PWM for now). From my googling I have made the attached circuit. However...
I can not get it to work unless I remove the 220Ohm resistor.
The motor speed is significantly slower than connecting it directly to the external 3 volt power supply (2 AA batteries). Too slow to be useable.
If I use another 3v battery pack to control the transistor instead of using the nano, the speed is a bit slower compared to connecting the motor directly to 3v. But much faster than when using the nano to control the transistor.
Is this expected or have I made a mistake?
Thanks!
this is the arduino sketch I am using to test:
//number of elements in arrays need to match for() cycles in void setup
int pinsIn[4] = {6, 7, 8, 9};
int pinsAnalog[8] = {0, 1, 2, 3, 4, 5, 6, 7};
int pin = 0;
int val = 0;
int pinsOut[4] = {2, 3, 4, 5};
void setup()
{
//set up a total of pins for digital input (has to match number of elements in array)
for(int i = 0; i < 4; i++)
pinMode(pinsIn[i], INPUT);
for (int i = 0; i < 4; i++) {
pinMode(pinsOut[i], OUTPUT);
digitalWrite(pinsOut[i], LOW);
}
//DEFAULT works with thermistors,
//INTERNAL with transitor thermostats
// ELLER var det tvartom???
analogReference(DEFAULT);
pinMode(A0, INPUT_PULLUP);
pinMode(A1, INPUT_PULLUP);
pinMode(A2, INPUT_PULLUP);
pinMode(A3, INPUT_PULLUP);
pinMode(A4, INPUT_PULLUP);
pinMode(A5, INPUT_PULLUP);
pinMode(A6, INPUT);
pinMode(A7, INPUT);
Serial.begin(115200); // perhaps use a faster baud rate
}
void loop()
{
Serial.print("knobs"); // use "knobs" as a keyword so you can receive
// the knob values as a list with a [r knobs] in Pd
for(int i = 0; i < 8; i++){
unsigned int knob = analogRead (pinsAnalog[i]);
Serial.print(" "); // first print a white space to separate the "knob" keyword from the values
// and the values from each other
Serial.print(knob); // then print the actual knob value
}
Serial.println(); // finally print a newline character to denote end of data for keyword "knobs"
// the same technique applies to the switches too
// receive the switch values as a list with [r switches]
Serial.print("switches");
for(int i = 0; i < 4; i++) {
int switchVal = digitalRead(pinsIn[i]);
Serial.print(" ");
Serial.print(switchVal);
}
Serial.println();
//handle digital outputs
if (Serial.available()) {
static int temp;
byte in = Serial.read();
if (isDigit(in)) {
temp = temp * 10 + in - '0';
}
else if (in == 'p') {
pin = temp;
temp = 0;
}
else if (in == 'v') {
val = temp;
temp = 0;
digitalWrite(pinsOut[pin], val);
}
}
}