mercury switch

[xylhak]

ei guys can i ask for some help...weneed to use a mercury switch for our project (the step counter) and it is not available here in our country...what do u think is the alternative switch for that?please help us...

[mixos]

You can use a switch of this type if it is suitable:



I can't find something closer to a mercury switch. You can also attach a bob on top of the foil to make it more motion sensitive.

[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

[MP]

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

[billy]

You can buy the kit 1150 (portabme alarm) from smartkit. There is a very good mercury switch in there ! :)

Or get in contact with smartkit and request one :)

[Dosbomber]

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.

[hotwaterwizard]

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.

[Ldanielrosa]

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.

[hotwaterwizard]

You could put a light weight spring in there to stop the bounce.
Anoyher way to replace the switch is with a magnetic reed switch.
A flow switch has a magnet in it and when you tilt the switch it will activate the reed switch.

[hotwaterwizard]

Ok here are a few links.

Tilt Switch Links

http://www.elexp.com/cmp_00tl.htm

http://www.electronicstalk.com/news/ase/ase102.html

http://www.solico.com/Optical%20tilt%20switch%20flyer.pdf

http://www.signalquest.com/

http://www.rapidelectronics.co.uk/products_sensors.htm

http://www.kelvin.com/Merchant2/merchant.mv?Screen=PROD&Store_Code=K&Product_Code=270086

http://www.fuji-piezo.com/tilt.htm

[steven]

:)

[trigger]

how about a magnetic switch, some step counter use it.
Also most now use plastic arm to do so.
I will try to search my old stuff to see if I can get you a picture of these mechanism.

[surajbarkale]

Found some info abt magnetic reed sw here http://www.allaboutcircuits.com/vol_4/chpt_4/2.html but there is no diagram to illustrate it :(

[hotwaterwizard]

The new Name they use is TILT Switch .
They now make them without Mercury. Mouser Has them and They can ship worldwide. Type in Tilt Switch in the Parts Search.
http://www.mouser.com/index.cfm?handler=data.getPcodes&pcode=Mountain%2BSwitch%2BTilt%2BSwitches&pcodenumber=01014

[hotwaterwizard]

Here is steven's Picture Modified so you can see it.

[sect8]

you can find mercury switches in household thermostats