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Snap Action Switch ?

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Rocketclar

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I'm sure this has been discussed before, but a quick search didn't answer my ? So....has anyone had an electronics failure with a snap action switch due to G forces causing a momentary closure? THX.
 

g.pitts

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I'm sure this has been discussed before, but a quick search didn't answer my ? So....has anyone had an electronics failure with a snap action switch due to G forces causing a momentary closure? THX.
No... but with a caveat. I use larger batteries (>500 mAh LiPOs) to provide power to the altimeter once I plug them in to the altimeters, and I replace my battery connectors with genuine Molex Mini-Fit Jr. connectors using their crimp tool and contacts. This line of connectors employs a latching mechanism to prevent inadvertent disconnection. My switches are controlling only the power applied to the altimeter outputs.

IMO switch orientation is really important. I selected the normally closed switch contacts for the power going to the altimeter outputs (Eggtimer Quantum, but could be done on any altimeter), and the switch is oriented so that the lever is oriented toward the tail of the rocket and horizontal to the ground. With this orientation, the acceleration of launch is pulling the lever away from switch actuation.

<edit> FWIW, I'm using this switch (PCB mount) and I've attached the datasheet as FYI. Always check the DC current rating on these switches - some are near-microscopic!
 

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Crayok

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Hi Rockclar
Most switches have some sort of spring in them which would be subject to g forces but not only g forces, vibration is another to consider. many don't spec a g force or vibration limit but some do. if not tested it can become a hope and prayer situation. below are some switch vibration spec ratings to consider. you will have to go search for the vibration and shock measurements.

You don't mention a flight profile which is hugely important, one solution does not fit all. Slow, short flights aren't subject to the same rigour as fast and maybe long flights. I know you are looking for what have other people had luck with.

Mechanical Ratings Vibration Resistance: Per Method 204, Test Condition B, 1 mS opening (10 mS allowed) Mechanical Shock: Per Method 213, Test Condition A. 1 mS opening (10 mS allowed) Thermal Shock Resistance: Per specification;
This is for a dip switch we have used in the past (and not suggesting you use this but to show it has a spec and the limits of the spec)
https://www.grayhill.com/documents/78-Datasheet

Spec test information I found here but I imagine there is an updated version out there somewhere, Method 202/213 and 204 are vibration method 214 is random
http://everyspec.com/MIL-STD/MIL-ST...IL-STD-202H_CONSOLIDATED_18APR2015.054374.pdf

Not a "I used this successfully" response but hopefully one you can apply to all your launches
David
 
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