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I am working on a new safety switch designed specifically for rocketry. Anywhere that your electronics will ignite a motor, and also in some ejection setups this switch is designed to improve safety and prevent accidental firing from mistakes or component failures.
The switch will be a highly vibration/acceleration resistant rotary switch designed to be mounted securely to the tube wall. It will have a universal key that cannot be removed in the first “Safe” position and will have a remove before flight tag. There is an additional “Safe” position in which the key can be removed if necessary, and of course it will be removable in the “Armed” position. There will be a colored indicator displaying the switch state. The switch will be armed after powering your electronics as the last step before flight. I am also considering offering an option with an additional pull pin that can be pulled on a string from a safe distance.
When in the safe position the switch will be shorted on both the altimeter and ignitor sides and there will be no circuit between the altimeter and ignitor. Additionally, when “Safe” there will be a replaceable fuse and buzzer connected to the altimeter. When the electronics are powered on in the case of a faulty altimeter or wiring sending high current to the ignitor the fuse will blow and the buzzer will sound to alert you of the problem. With the fuse blown no connection will be made between the electronics and ignitor. When armed the switch will un-short and connect the altimeter through to the ignitor as normal.
I have already completed a number of tests of the switch circuit with, low current e-matches and high current ignitors, with small single lipos and a 12V 20A wall supply, simulating an altimeter firing before and after armed. In every test the circuit performed as expected, the pyros fired when intended and at no other time.
The switch is being designed to be able to handle 20+ amps but an official spec will need to wait for testing. It should work at any voltage between 3.5-16V (buzzer limited).
Any feedback on this would be greatly appreciated as I continue testing and development.
The switch will be a highly vibration/acceleration resistant rotary switch designed to be mounted securely to the tube wall. It will have a universal key that cannot be removed in the first “Safe” position and will have a remove before flight tag. There is an additional “Safe” position in which the key can be removed if necessary, and of course it will be removable in the “Armed” position. There will be a colored indicator displaying the switch state. The switch will be armed after powering your electronics as the last step before flight. I am also considering offering an option with an additional pull pin that can be pulled on a string from a safe distance.
When in the safe position the switch will be shorted on both the altimeter and ignitor sides and there will be no circuit between the altimeter and ignitor. Additionally, when “Safe” there will be a replaceable fuse and buzzer connected to the altimeter. When the electronics are powered on in the case of a faulty altimeter or wiring sending high current to the ignitor the fuse will blow and the buzzer will sound to alert you of the problem. With the fuse blown no connection will be made between the electronics and ignitor. When armed the switch will un-short and connect the altimeter through to the ignitor as normal.
I have already completed a number of tests of the switch circuit with, low current e-matches and high current ignitors, with small single lipos and a 12V 20A wall supply, simulating an altimeter firing before and after armed. In every test the circuit performed as expected, the pyros fired when intended and at no other time.
The switch is being designed to be able to handle 20+ amps but an official spec will need to wait for testing. It should work at any voltage between 3.5-16V (buzzer limited).
Any feedback on this would be greatly appreciated as I continue testing and development.