Duckling project

I need a control circuit for a simple toy. I have a 1.5- 3V DC motor to be powered preferable by 2 AA cells. I wish the control circuit to operate as follows. A momentary switch to activate a timer circuit. The on time to be able to be set by a variable resistor to between 30 sec and 3 minutes. accuracy +/- 20% On activation of the momentary switch the timer should count down and the output of the circuit V+ should energise the DC motor in the forward direction. At the end of the timing interval the output to the motor needs to be reversed until the motor parks and stalls against a mechanical latch at this point the timer is switched off. This can be triggered by current sensing of the stall current ,or by a micro-switch as in the prototype circuit. If the momentary switch is pushed again during the timing period the timing should end and the circuit behave accordingly by reversing polarity. A tone should be generated during the reversing phase of the motor. The circuit should have minimal current drain in standby mode. I believe that this design can be achieved using a timer and H-Bridge e.g. 555 and 8837 Currently the prototype uses a simple timer and a relay to reverse the polarity.