Tilt Switches

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Aquaman33
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Tilt Switches

Postby Aquaman33 » Wed Aug 29, 2018 9:20 pm

Hi all,

I am working on a project with my kids and they want to include a buzzer that goes off to help recover the rocket.

I thought it would be fun to include a tilt switch that triggers the buzzer when the rocket is on the ground.

I have seen lots of commercially available ball bearing tilt switches like this one:

Image

But I would need at least 3 of these at different angles to cover all the orientations that the rocket could land in.

Ideally I'd like a single switch that works at any angle greater than say 20 degrees away from vertical.

So I mocked up this rather crude medieval looking "pendulum switch":

Image

Image

The negative wire would be attached to the pendulum and the positive to the metal ring. When the rocket is vertical the pendulum hangs in the middle and the circuit is open. When the rocket lands the pendulum touches the metal ring, the circuit is closed and the buzzer sounds.

I would obviously make a neater/smaller version for the rocket. This was just a proof of concept.

This diagram better illustrates the principle:

Image

My question is are there any commercially available versions of this switch and if so what are they called?

I have seen lots of Arduino tilt sensors online, but that's a bit complex for my kids and I. We just want a switch.

Thanks in advance for your thoughts.

Derek

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OverTheTop
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Re: Tilt Switches

Postby OverTheTop » Thu Aug 30, 2018 7:44 am

DigiKey have a good range of tilt switches. Some are silicon-based, some mechanical. C&K have a range with varying sensitivity to tilt, and multiple angle determination capabilities.
https://www.digikey.com/products/en/sen ... t%20switch

I use one of these in my VTS system to detect whether it is in pad/boost mode, or coasting.
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Aquaman33
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Re: Tilt Switches

Postby Aquaman33 » Mon Sep 17, 2018 9:45 pm

OverTheTop wrote:DigiKey have a good range of tilt switches. Some are silicon-based, some mechanical. C&K have a range with varying sensitivity to tilt, and multiple angle determination capabilities.
https://www.digikey.com/products/en/sen ... t%20switch

I use one of these in my VTS system to detect whether it is in pad/boost mode, or coasting.


Thanks OverTheTop. There are some great options on Digikey's website. I am going to place an order, but haven't got around to it yet.

I did order a bunch of ball bearing switches from Banggood and Ebay.

These ones:
https://www.banggood.com/10Pcs-SW-200D-Ball-Switch-SW-200D-Tilt-Angle-Sensor-Switch-Double-Bead-Angle-Switch-Transducer-p-1094203.html?rmmds=search&cur_warehouse=CN

And these ones:
https://www.ebay.com.au/itm/10Pcs-SW-200D-Vibration-Rolling-Angle-Sensor-Electronic-Tilt-Shaking-Switch-Z/142840972186?hash=item2141fc439a:g:v6gAAOSwfi9ZrMm6
10 cents each including postage! :D

I have done some testing and both types seem to work well.

So I mocked up a simple tilt switch by combining 3 ball bearing switches in a kind of inverted tripod formation.

Image

Image

Image

In the upright position the circuit is open because all 3 ball bearings at the bottom of the switches. When its tilted at least one, but often two ball bearings roll to the other end of the switch and close the circuit.

To reduce the weight and size I connected the switches together using copper tape. Its good stuff and should cope with vibration well.

I have tested it with a buzzer in a nose cone and it worked great providing the nose cone landed somewhere close to horizontal. I think I can fine tune it by playing around with the angle of the ball bearing switches.

I used an old piece of PVC angle for the mount.

For a first prototype I'm happy.

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SpaceManMat
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Re: Tilt Switches

Postby SpaceManMat » Tue Sep 18, 2018 12:22 pm

You might want to check out Air Command’s work on tilt mechanisms.

http://www.aircommandrockets.com/day136.htm
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Aquaman33
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Re: Tilt Switches

Postby Aquaman33 » Tue Sep 18, 2018 6:44 pm

SpaceManMat wrote:You might want to check out Air Command’s work on tilt mechanisms.

http://www.aircommandrockets.com/day136.htm


Great video, which I have watched a few times.

George really should be hosting Mythbusters.

I definitely won't be using tilt switches for deployment!


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