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PostPosted: Thu Jan 27, 2005 4:41 pm 
Clawhammer
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Even better: Get some touch sensitive switches. I have a couple laying around here that you barely have to touch and it turns on. (theres a prank here somewhere, I just can't think of one...)


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PostPosted: Thu Jan 27, 2005 4:53 pm 
Smithfield*
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hrm, sit down and have your computer turn off... run your pc in a windy room and it'l be on/off every few seconds....i dunno


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PostPosted: Thu Jan 27, 2005 5:22 pm 
Clawhammer
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They're not THAT sensitive, besides I was thinking of using them for maybe an optical drive or CCFL switch. I would be worried about using them for power becasue I would always bump into them.


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PostPosted: Sat Jan 29, 2005 6:28 pm 
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Chumly, if you want a bunch of the reed switches you mentioned, feel free to email me: ron at bearblain dot com and I will send you a bunch. I use them all the time for position indicators. Likewise the momentary On switches. You are on your own for the magnetic donut though.


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PostPosted: Sat Jan 29, 2005 8:12 pm 
Boy in Black
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Thanks dude! Got an estimated size on these things? boynblack at sbc global dot net :D

My reservoir I'm building is about 3-1/2" high, but can adopt a new design to accomidate something cool like this. And maybe one of these toroidal magnets can float somehow...dunno.

I'll have to devise a sender too, so some ideas would be great since you work with these already. Forgot to ask you about this from the get-go.


(Go Savage! Any word up there locally about Romeo Crennel? Sorry...I'm still out of the loop:p)


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PostPosted: Sun Jan 30, 2005 5:00 pm 
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No problem. The way these things work as you have seen them is simple and yet complicated. Your needs will be simple. On a ships fuel tank there are a series of switches on a long circuit board. The board is encapsulated in a stainless steel (non magnetic core). The donut you refer to is a magnet.

The switches are spaced at exactly 1" centers on the board. The strength of the magnetic field determines what switches close. That is to say the 0" and no other switch is closed meand you are so screwed! OK seriously, if the 1" and 2" switches are both closed that would be 1.5" of fuel in the tank. However, if only the 1" switch is closed, then you have 1" of fuel. Based on the dimentions of the tank, that could easily convert to gallons.

Here nor there. I liked your thoughts on how a computer wiith water cooling should have a "Go Ahead" much like a gasoline engine should for oil. However, there are problems. The power button on a PC simply places a +5 volt logic level to ground. That is why the switch proposed in this thread won't work. Like you said, MOMENTARY! The problem becomes that the only active (like it is really there) PSU power prior to pushing the Power button is a lousy 5 volt pull down voltage.

If you want some of the switches you mentioned, no problem. I can shove some in a box and send them. However, short of an active psu prior to start up, we are still screwed. Now once up and running, a water level indicator would be easy. Just need a damn magnetic donut? Radio Shack?

Ron


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PostPosted: Mon Jan 31, 2005 10:46 am 
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idea for the donut... get a bolt and bend it into a hoop shape... then wrap it in copper wire and hook it up to a 12 v battery or some power source... it forms an electromagnet... we did this in physics class last year... has to be a fairly tight wrap too... then you'd have to find some way to keep it from coming in contact with the liquid to keep out a short. i think its black to the bolt and red to the copper wire... but in any case just an idea


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PostPosted: Mon Jan 31, 2005 5:16 pm 
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We use two sizes. The smaller ones are maybe 3/4" long and maybe a little less than 1/8th inch wide (round). They would likely fit into a drinking plastic straw. This would allow for a few small gauge wires at an exit point which could be sealed with epoxy.

Since the typical reservoir is only a few inches deep, I would configure a single switch, so the centerline was maybe at the level where you wanted a warning prompt or something.

Back to the infamous donut. I would swear I have seen round magnets that were like tiny donuts maybe at radio shack? Yep, just checked and found:

<Made of iron and metal oxides, these powerful 1-1/8" round magnets are great for using around the house, shop, office or car. Five per package.>

Radio Shack web site and keyword search of magnets, $2.59 for 5 of them. Cheap little suckers.

Basic indicator circuit could be as simple as a LED, piezo buzzer, or whatever.

Ron


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