Substitutes for mercury switches
Substitutes for mercury switches
(OP)
With the need to remove mercury from many industrial applications, what are the substitutes for mercury switch applications?
Thanks
Thanks
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Substitutes for mercury switches
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Substitutes for mercury switchesSubstitutes for mercury switches(OP)
With the need to remove mercury from many industrial applications, what are the substitutes for mercury switch applications?
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RE: Substitutes for mercury switches
are you using the mercury switch for HIGH ARCING applications?
can you name few applications?
thanks
dydt
RE: Substitutes for mercury switches
I just got an email from a friend who is working with disabled children making "toys" that aid in their making more use of their limbs. For instance, he writes, "By using several mercury switches, you can vary how high the child’s arm must arc before the toy turns on." He's coming up with low-cost ways that are alternatives to conventional therapy.
From this I would gather that we're looking at low voltage/current applications.
RE: Substitutes for mercury switches
The same could be done using the microswitches and as per requirement the position of the switch could be adjusted to vary the arcing of the arm of the child.
RE: Substitutes for mercury switches
If anyone can offer some ideas - alternatives to low votage/low current mercury switches - I'd appreciate it.
Thanks,
Country
RE: Substitutes for mercury switches
Another idea: rip open one of those dolls that close their eyes when they lay down. Duplicate their design, or rip out one of the eyes (sorry for that gory picture) and attach a small proximity detector (maybe a magnetic switch) to the eyelid.
Yet another idea: most irons are designed to shut off if they tip over. Rip open an iron and see how that works.
One last idea: electronic gyroscope or compass from Radio Shack.
RE: Substitutes for mercury switches
RE: Substitutes for mercury switches
A more pragmatic approach might be to minimise the hazards of mercury switches (breaking and releasing the mercury) by potting the switch in epoxy or similar.
http://www.sensorsmag.com/articles/0500/120/main.shtml
RE: Substitutes for mercury switches
I'll forward the link to my friend. Looks good.
He does pot the switches. In his mail to me he said, "Sometimes there’s no control devices that are available, so I had to make them myself. A mercury switch encased in an aluminum tube, sealed with hot glue or epoxy is a handy switch to use...."
Thanks again.
RE: Substitutes for mercury switches
I'm the one who's daughter is disabled. The mercury switches I use are placed in steel or aluminum tubes then are sealed with hotglue or epoxy. There's little worry about leakage since they're sealed. Granted, what can be sealed can become unsealed, but you are really going to have to work hard at unsealing these. Irresponsible, no. Ignorant, only if you think I'm going to be irresponsible with such materials.
In my area, mercury switches are easy to get. I can get them at Radio shack, electrical industrial warehouses, and just about any where else that serves an industry that needs such things. However, I am open to using something less hazardous than mercury because it’s my preference. I had considered using a small ball bearing, BB, et al in a metal tube with a contact at one end. However, there’s the arcing factor that could make the toy stop working. I’ve considered using nitrogen to keep the carboning of the contacts, but I’m not sure if this is worthwhile if there’s something else that’s readily available. Also, injecting nitrogen may be more work than it’s worth.
The advantage of the mercury switch is it’s not direction sensitive. You don’t have to be concerned if the child is holding the device correctly. If there’s something else that’s off the shelf, I’ll be most appreciative to be informed.
RE: Substitutes for mercury switches
RE: Substitutes for mercury switches
RE: Substitutes for mercury switches
http://www.spectronsensors.com/index.html
RE: Substitutes for mercury switches
These tilt sensors seem to be the ticket for what I'm doing! Are they self supporting or do they work in conjunction with something that decipher the sensor's signals? I'm going to have to look into these things. Price is also a consideration. Some of these parents are strapped for cash because of the cost of therapy, equipment, et al. The cost of a manual wheelchair can run well over $1400. A power chair can cost around $40,000. Some of these parents have trusts for their child. Some have only insurance. In either cases, the parents have to pay out of pocket because the equipment isn't covered under the trust contract, and the insurance won't cover what they call "experimental" equipment. Quite often, I either give the toy to the kid outright or I charge only for the parts. I can afford to give away only so much. There's been times where I make less off this than what I make because these kids' needs. If the costs are low, I can afford get more of these pieces of equipment to the kids.
RE: Substitutes for mercury switches
A general scheme like this should work and be very cheap. Make a simple CMOS oscillator using 3 gates from a hex schmidt trigger inverter. Feed the oscillator output through the electrolyetic sensor to the 4th gate which acts as a buffer and drives the beeper. Parts count ~$1.00
Generallty though there will be some conditioning circuit needed.