#include <QDebug>
#include <QThread>

class Worker : public QObject
{
    Q_OBJECT

public:

    Worker();
private slots:
    void onTimeout();

private:
    int counter;
};

#include "worker.h"

Worker::Worker()
{
    counter = 0;
}

void Worker::onTimeout()
{
    qDebug()<<"Worker::onTimeout get called from?: "<<QThread::currentThreadId();
    counter++;
    //if (counter == 3)
    // stopTimer();
}

#include <QMainWindow>
#include <QDebug>
#include <QThread>
#include <QTimer>
#include "worker.h"

namespace Ui {
class MainWindow;
}

class MainWindow : public QMainWindow
{
    Q_OBJECT

public:
    explicit MainWindow(QWidget *parent = 0);
    ~MainWindow();

private:
    Ui::MainWindow *ui;

    QThread t;
    QTimer timer;
    Worker worker;

private slots:
    void onInit();
    void onStart();
};

...
    connect(ui->pushButton_2, SIGNAL(clicked()), this, SLOT(onStart()));
...
//------------------------------------------------------------------------------
void MainWindow::onStart()
{
    qDebug()<<"From main thread: "<<QThread::currentThreadId();

    QObject::connect(&timer, SIGNAL(timeout()), &worker, SLOT(onTimeout()));
    timer.start(1000);

    worker.moveToThread(&t);

    t.start();
}

class Worker : public QObject
{
    Q_OBJECT

public:

    Worker();
    void start();

private slots:
    void onTimeout();
    void stop();

signals:
     void stopTimer();

private:
    int counter;
    QTimer timer;
};

Worker::Worker()
{
    counter = 0;
    QObject::connect(&timer, SIGNAL(timeout()), this, SLOT(onTimeout()));
    QObject::connect(this, SIGNAL(stopTimer()), this, SLOT(stop()));
}

void Worker::start()
{
    timer.start(1000);
}

void Worker::stop()
{
    timer.stop();
}

void Worker::onTimeout()
{
    qDebug()<<"Worker::onTimeout get called from?: "<<QThread::currentThreadId();
    counter++;
    if (counter == 3)
    {
        emit stopTimer();
        //timer.stop();
    }
}

//------------------------------------------------------------------------------
void MainWindow::onStart()
{
    qDebug()<<"From main thread: "<<QThread::currentThreadId();

    worker.moveToThread(&t);
    worker.start();

    t.start();
}