HALL SENSOR CIRCUIT-- HELP NEEDED

[magnetman12003]

I have decided that I can use a hall effect sensor to power a device I already made. Not a latch type sensor.
What I am looking for is a very simple 12 volt hall sensor circuit that will be able to momentarily power on-off a rather large 12 volt electromagnet coil.  As I understand the sensor can be damaged if the gauss ratings of any magnet near it is to high.  I am using large powerful N48 magnets.  I also understand that the back EMF off the coil when power is taken away might damage the sensor.  Might I need a diode type snubber in parallel with the coil?

So is there a simple circuit I can use that I should not have problems with?
Greatly appreciate a hand drawing of all component parts and schematic.

Thanks
Tom

[Magluvin]

Whole bunch of ideas here....

https://images.search.yahoo.com/search/images;_ylt=AwrBT4TZLHtWpSoADcVXNyoA;_ylu=X3oDMTE0ZjVmY2N1BGNvbG8DYmYxBHBvcwMxBHZ0aWQDV09EQzBfMQRzZWMDcGl2cw--?p=hall+sesor+trigger+mosfet+circuit&fr=fp-comodo&fr2=piv-web

Mags

[skycollection]

Magnetman, here is my link, you can find a circuit with hall sensor, (EXPERIMENTAL CIRCUITS FROM SKYCOLLECTION) this circuit is for 12 volts, and never burn the hall sensor, i used for years without problem...!


http://overunity.com/15560/skycollections-pentafilar-pancake-inductively-coupled-overunity-potential/105/#.VntbU_nhCUk

[TinselKoala]

I have decided that I can use a hall effect sensor to power a device I already made. Not a latch type sensor.
What I am looking for is a very simple 12 volt hall sensor circuit that will be able to momentarily power on-off a rather large 12 volt electromagnet coil.  As I understand the sensor can be damaged if the gauss ratings of any magnet near it is to high.  I am using large powerful N48 magnets.  I also understand that the back EMF off the coil when power is taken away might damage the sensor.  Might I need a diode type snubber in parallel with the coil?

So is there a simple circuit I can use that I should not have problems with?
Greatly appreciate a hand drawing of all component parts and schematic.

Thanks
Tom

Here's how I would do it. I'd use a mosfet to switch power to the coil. I'd trigger the mosfet with a 555 monostable circuit, whose timing can be adjusted to turn the mosfet on for however long I need. I'd trigger the 555 monostable with the output of the linear Hall sensor, or even better with the output of a simple op-amp comparator, with the Hall sensor as one of the inputs to the op-amp.

So you'd have

Linear ratiometric Hall sensor > Op-amp comparator > 555 monostable > mosfet > coil

This scheme will allow you to put the Hall sensor in a fixed position, then vary its sensitivity using the op-amp. The timing components (trimpot+capacitor) of the 555 monostable circuit will allow you to set the ON time of the coil.

Hall sensor: Allegro A3503 or similar won't be harmed by strong fields
Op-amp: TL082 has 2 amps per chip
555: very versatile timer chip
mosfet: Depending on your coil and your supply voltage, try IRF3205 or other R_dson mosfet

You are probably looking at about 5 or 7 dollars US worth of parts here.

The image below is the basic op-amp part of the circuit but without the 555 monostable stage, since I want the spinning ball magnet itself to regulate its own timing.

Merry Christmas!

[magnetman12003]

I have decided that I can use a hall effect sensor to power a device I already made. Not a latch type sensor.
What I am looking for is a very simple 12 volt hall sensor circuit that will be able to momentarily power on-off a rather large 12 volt electromagnet coil.  As I understand the sensor can be damaged if the gauss ratings of any magnet near it is to high.  I am using large powerful N48 magnets.  I also understand that the back EMF off the coil when power is taken away might damage the sensor.  Might I need a diode type snubber in parallel with the coil?

So is there a simple circuit I can use that I should not have problems with?
Greatly appreciate a hand drawing of all component parts and schematic.

thanks for all your input fellows.  I am going to use the hall circuit to trip a ""Free Floating"" huge heavy ball magnet to travel in a 360 circular fashion. Every 360 degrees it will need a kick from a electromagnet to keep it going.  There is no sticky spot to deal with either so the ball magnet should travel faster and faster.  Similar action like the below setup but made a very different way not posted anywhere on the net  Will post when finished.  All finished except the hall circuit.  It works by finger touch so far and the hall circuit will definitely take it to another level.

https://www.youtube.com/watch?v=Bodv-gvoO2A

Thanks
Tom