I am stuck in the middle of building a circuit for an aircraft starting mockup that will train our students to correctly start the aircraft without accidentally re-engaging the starter and thus causing very costly maintenance actions.The system is 12v.
We would like to have a 10 second delay timer switch that will turn on a light when the start sequence has been successfully completed. This part seems simple because when the ignition switch is turned to start, it closes the contacts and starts the 10 second delay timer that turns on the light if held closed for 10 seconds. I found one of these timers on amazon but could not find anything for the next part of the mock up.
The complex component of the circuit I can’t figure out is that I would like to have a buzzer in the circuit. If the student accidentally releases the ignition switch even for a moment during the 10 second starting sequence then this buzzer would go off using something like a latch circuit that turns on and keeps a buzzer on until it is reset.
What is confounding me is how to create this circuit so that the buzzer is not going off when:
- The system is initially powered up.
- The contacts are closed when the ignition switch is turned on for a start sequence
- The 10 second starting sequence is completed successfully and the starting key is released thus opening the starting circuit contacts.
We only want this buzzer to go off if the student fails to hold the ignition contacts closed during the 10 second starting sequence.
Could someone please help me design this circuit and let me know what components I need to in order to build it?