Mercury Tilt Switch: Availability & Alternatives

[hazim]

mercury tilt switch?

hi...is mercury switch available in stores and can be easily found?? also is there some circuit that functions same as the mercury switch?

 

[mgb_phys]

If you can't find them in stores they are common in room thermostats (at least in the US)
There are alternatives but many are either sensitive to vibration or have a limited lifetime

 

[berkeman]

I googled mercury tilt switch, and got lots of hits.

http://www.google.com/search?source...&rlz=1T4SUNA_en___US232&q=mercury+tilt+switch

 

[dlgoff]

"also is there some circuit that functions same as the mercury switch?"

Bimetal switches are used like mercury switches in themostats.

Edit: I guess this really doesn't make much sense. Even with the mecury switches; they are attached to a bimetal coil that tilts the mecury tube as the temperature changes.

I was thinking of the ones where there is a contact on the coiled bimetal that make to a stationary contact when the temperatures changes.

 

[Integral]

"also is there some circuit that functions same as the mercury switch?"

Bi metal switches are used like mercury switches in thermostats.

no, it is usually a bi metal strip that tips the mercury switch. The mercury switch makes and breaks the circuit, the bi metal strip bends with temperature and in conjunction with the knob determines the temp at witch the mercury switch tips.

 

[berkeman]

also is there some circuit that functions same as the mercury switch?

For alternatives (which would be good, considering how toxic mercury is), look to the geometry of what you are trying to do. If you are sensing the lid of something being opened, you can use a mechanical spring-loaded push-switch to tell you when the lid is closed, and when it is opened. Or, you can use the magnet+reed sensor pair things that are commonly used to sense door openings for alarm systems. The magnet is mounted on one surface, and as the door/window is closed, that brings the reed unit in close enough proximity to close the reed contacts.

You can also use simple rotary encoders to tell when something is being tilted (about some axial arrangement), or more sophisticated sensors for other arrangements and movements.

What is your target geometry?

 

[Danger]

A simple ball-bearing in a non-conductive tube works well; just stick a couple of bare wires side-by-side in one end. Also, a piece of chain going through a cork into a tin can--connect one side of your circuit to the chain and the other to the can. There are lots of variations upon both of those.

 

[rbj]

considering how toxic mercury is

when i was a kid, many times i used to hold a glob of it in my hands. lotsa fun.

hat making was a pretty safe vocation (better than stripping the silver offa photographic film using cyanide) and lead goblets didn't hurt anyone.

 

[hazim]

i just liked to construct this circuit http://www.redcircuits.com/Page9.htm ...anyway thanks for all; i think it will be less exactitude and somehow hard to do it in mechanic way...