Hi all
I need a simple switch thats triggered by a magnitic field. Would like to use a hall effect sensor but I'm sure how to wire them as a simple switch. It will only be switching very low current, a datalogger / timer.

Thanks in advance.

Dave

 

Hiya Dave,
The 1101 hall effect sensor from allegro is a top hall effect sensor. I've set one up with a 3x3x3 neo to use as an anometer for checking the wind speed so I can determine the best place to put a wind genny. It puts out a 5 volt pulse every time it see's a south pole. This could be just what your looking for.

Hope this helps

Cheers Bryan

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" The only way to avoid human error is to avoid the use of humans"

 

Thanks Bryan,
I was looking more for a simple "contact closure" type switch, not a pulsed output.

From the Hills, does the Name "Dave Crispen? ring a bell??

 

Well Dave the pulsed output could go to a 555 one shot timer, a pic microcontroller or anything to process the pulse. Now there are some hall effect sensors that latch but I don't know any part numbers of them.

Anyway mate the name you mentioned does ring a bell but it would be around 10 years or so as I lived in WA for about 5 years before moving back to SA.

Cheers Bryan

__________________
" The only way to avoid human error is to avoid the use of humans"

 

You don't really give enough details?, but from your vague requirements it sounds like all you need is a reed relay?.

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A reed switch and a magnet will work fine if only simple on off indication is required.
For data logging a pull up or pull down resistor may be required depending if the data logger has open collector inputs.
Some contact bounce can be filtered out with a schmitt trigger 7413 or 40106 if needed.

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There are more ways to get to Rome.

Electricity, Electric clocks, Meters and Trains are great.

 

note that there are different forms of HE sensors. it sounds like (in the face of minimal data...) that you want a latching HE switch. all sorts of different kinds. one that I've used latches on with a south, off with a north, iirc.

 

Thanks all, looks like I need to give you all a bit more info...
I have a datalogger lap timer that (at the moment) is manual. That is the lap timer is operated by a push button, the tracks we race on have a magnitic strip
inbeded in asphelt. I want to replace the push button with a hall effect to make it automatic. A reed switch is no good. The hall effect will be about 30-40mm from the maginet.

Thanks.

 

Anymore thoughts anyone???

 

I think you will have to experiment. 30 mm is a pretty far distance for an HE sensor and you don't say how strong the magnet is (I'm sure you don't know).

I'd order a selection of HE sensors. Allegro is fairly generous with samples. your first problem will be setting up a test case. Once you are able to sense the the strip, you can build something to trigger the timer. But with no details on the timer, there is little help you can expect