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mercury switch


xylhak
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Guest Junkman

Depending on your needs and design, you might be able to use a reed switch and magnet to serve the same purpose. I don't know what movment you are trying to detect, so can't offer anything more specific. Magnets are everywhere, and reed switches are available from may electronics suppliers, and may also be salvaged from some old or un-needed electronic equipment. (Old adding machines are a one such good source)
Hope this helps.
Junkman

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  • 4 months later...

If this is refering to the following project:
http://www.electronics-lab.com/projects/misc/007/index.html
Then I do not think that you are going to be very successful with using a different type of switch in the same place. ;D The mercury switch is meant to be in your pocket and the movement of the switch activates the count. The closest option might be to use a switch such as Mixos has suggested and connect it to the shoe so that it triggers with each step. This is probably the simplest substitution.
Another option might be a sound transducer, but it will require more circuitry to give you a trigger from the step.
MP

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  • 1 month later...

It's very hard to find Mercury in anything anymore. I believe the main reason for this is that it's so darn toxic.

I looked for a long time for one for flip-sensors on some robots I was building, before breaking down and going to sciencelab.com to actually buy the stuff, then building my own. Small acrylic tubing works pretty well as a casing.

If you do this, be extremely careful when handling the Mercury.

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Okay, here is my solution.
A sump pump has a switch that will make contact when it is up or down depending on the position of the contacts. They are no longer leagal to use Mercury in them. They came up with a simple solution.
They have a ball bearing that rolls into a switch like they described in one of the previous reply. The whole assembly is inside of a plastic ball that floats on top of the water. The wire is tied to a pipe so it will move only up and down. When the water level drops to a set level the ball bearing rolls down and pushes on the switch, The key here is to use a ball bearing that is heavy enough to activate the switch but not heavey enough to break it when it rolls. Another way is to use the following diagram instead.

post-787-14279141593524_thumb.jpg

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I'm surprised there aren't alternatives for tilt switches in your neighborhood. I have trouble finding a catalog that doesn't have something in this category. Granted, a steel ball rattling about inside a cage won't make as good a connection as a puddle of mercury, but it's something to start with.

It does bring up a puzzle though. It'll have nasty bounce, so you'll have to write some pretty aggressive software to figure out what's being done to the device.

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