为什么 QTimer 不起作用？

该按钮btn是唯一的窗口小部件。它绑定到new_thread创建新线程的方法。

线程内部有一个方法func_1。它必须创建一个计时器 3 次，其操作应导致调用func_2. 由于某种原因，方法代码func_2没有被执行。请告诉我我做错了什么？

from PyQt5 import QtCore, QtWidgets

class MyThread(QtCore.QThread):
    def __init__(self, parent=None):
        QtCore.QThread.__init__(self, parent)

    def run(self):
        print('THREAD: run')
        self.func_1()

    def func_1(self):
        for i in range(0, 3):
            print('a')
            QtCore.QTimer.singleShot(150, self.func_2)

    def func_2(self):
        print('This doesn`t work :(')


class MyWindow(QtWidgets.QWidget):
    def __init__(self, parent = None):
        super().__init__(parent)

        box = QtWidgets.QHBoxLayout(self)

        btn = QtWidgets.QPushButton('Button', clicked = self.new_thread)
        box.addWidget(btn)

    def new_thread(self):
        self.mythread = MyThread()
        self.mythread.started.connect(self.on_started)
        self.mythread.finished.connect(self.on_finished)
        self.mythread.start()

    def on_started(self):
        print('THREAD: start')

    def on_finished(self):
        print('THREAD: finish')


if __name__ == '__main__':
    import sys
    app = QtWidgets.QApplication(sys.argv)
    window = MyWindow()
    window.setWindowTitle(' ')
    window.show()
    sys.exit(app.exec_())

UPD

from PyQt5 import QtCore, QtWidgets

class MyThread(QtCore.QThread):
    singlTimer = QtCore.pyqtSignal()

    def __init__(self, parent=None):
        QtCore.QThread.__init__(self, parent)

    def run(self):
        print('THREAD: run')
        self.func_1()

    def func_1(self):
        for i in range(0, 3):
            print('a')
            self.singlTimer.emit()

    def on_singlTimer(self):
        QtCore.QTimer.singleShot(150, self.func_2)

    def func_2(self):
        print('This doesn`t work :)')


class MyWindow(QtWidgets.QWidget):
    def __init__(self, parent = None):
        super().__init__(parent)

        box = QtWidgets.QHBoxLayout(self)

        btn = QtWidgets.QPushButton('Button', clicked = self.new_thread)
        box.addWidget(btn)

    def new_thread(self):
        self.mythread = MyThread()
        self.mythread.started.connect(self.on_started)
        self.mythread.finished.connect(self.on_finished)

        self.mythread.singlTimer.connect(self.mythread.on_singlTimer)

        self.mythread.start()

    def on_started(self):
        print('THREAD: start')

    def on_finished(self):
        print('THREAD: finish')


if __name__ == '__main__':
    import sys
    app = QtWidgets.QApplication(sys.argv)
    window = MyWindow()
    window.setWindowTitle(' ')
    window.show()
    sys.exit(app.exec_())