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Using Hall Effect Sensor to reverse current

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Mr. Arkham

New Member
Hello and thanks for hosting a great forum. I've been looking around through search and couldn't find quite what I was looking for, so here goes:

I'm pretty ignorant regarding electronics in general so please forgive me!

What I'm attempting to do is have some sort of sensor (Hall effect sensor?) that will detect a magnetic field and reverse the current of an electromagnet. The current will remain the same until the sensor detects another magnetic field and then switch again.

I posted this over at All About Circuits Forum as well and have been given a good place to start.

It seems I need a hall effect sensor attached to a SR Flip-flop which in turn is attached to an H-bridge that will reverse the current when the sensor detects magnetism.

The problem is I'm not really sure how to 'wire' all this up. Are there any examples of this already that I may look at?

I thought about designing my own simple h-bridge since it doesn't need to regulate current or anything.. just switch current back and forth.

Any help is greatly appreciated.

Thanks,
 

Mr. Arkham

New Member
THANKS!! Now, just run it into an H-bridge, hook up the 'juice' and give it a shot! eh?

Also....Oh, wait.. how fast do you think that capacitor can fire per minute?
 
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Roff

Well-Known Member
You can make a toggle flip-flop (divide by 2) with a D flip-flop such as CD4013, with the *Q output connected to the D input. Tie the Set and Reset inputs to ground. Tie all inputs (not outputs) of the unused section (CD4013 is a dual FF) to ground.
The Q and *Q outputs are complementary, and can possibly be used to drive your H bridge. If you design your own, you will have to deal with shoot-through.
 

Mr. Arkham

New Member
Thanks Ron! OK, so.. by going off the other suggestion.

Use a Reed Switch to detect magnetism (Interesting article on Reed switches I read)
The Reed switch will then tell the flip-flop contraption/combination that you mentioned to 'switch' and then send that to the H-bridge which will switch the current, yes?

Maybe I'll just buy an H-bridge (one that can handle high amps, like 35A-50A) once I figure what the hell I'm doing!!
 
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Roff

Well-Known Member
Thanks Ron! OK, so.. by going off the other suggestion.

Use a Reed Switch to detect magnetism (Interesting article on Reed switches I read)
The Reed switch will then tell the flip-flop contraption/combination that you mentioned to 'switch' and then send that to the H-bridge which will switch the current, yes?

Maybe I'll just buy an H-bridge (one that can handle high amps, like 35A-50A) once I figure what the hell I'm doing!!
A reed switch will have to be debounced. A Hall Effect device with hysteresis will not.
 

Sceadwian

Banned
Hall effects are cheap and reliable as well, reed switches are cheap and reliable, but nto as reliable as a solid state device.
 

Mr. Arkham

New Member
I really appreciate everyone's time providing information. I just wish I knew more of what circuits/devices were available so I could get this thing put together.

I'm going to need about twenty of them for an experiment if I can get the first one working.

There's so many kinds of each component out there; it's overwhelming to me--especially when I'm so out of it with electronics.

But more importantly, I still don't fully understand how it's going to work. I've been told what, I just need to read more and figure out how.. it's all gates and truth tables, right? *laughs*.. and I know that the how of things is probably beyond everyone's time and willingness; I completely understand! Any more advice is very appreciated! I just wanted to let you all know! :)
 

Mr. Arkham

New Member
I'm thinking of starting with 24V, but I would like something to handle high amperage as well.. like on the order of 35A.. Thanks!

Edit: Apparently I can create a very strong magnetic field with only 3 volts! (Two D batteries) I don't know what the amperage would convert to but I have a feeling the coil is going to be big!

So, (do you have any suggestions?) let's say 3 volts!
 
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Mr. Arkham

New Member
I haven't really found an answer to this question (so many things to read about):

Could a Hall sensor be destroyed if a magnetic field is too strong?
Can the sensitivity be preset to a certain field strength?

I'll keep looking! Thanks!
 

Roff

Well-Known Member
I haven't really found an answer to this question (so many things to read about):

Could a Hall sensor be destroyed if a magnetic field is too strong?
No.
Can the sensitivity be preset to a certain field strength?
I'm no expert on Hall effect devices, but I don't think so.

I'll keep looking! Thanks!
I think your biggest challenge will be finding a design for an 800 Watt H-bridge.
 

tcmtech

Banned
Most Helpful Member
So what is it your building that needs to sense so many magnetic fields and cause and H - Bridge to reverse?
 

Mr RB

Well-Known Member
Try a google search for "electronic controlled pendulum".

You can buy a complete controller in some of those desktop novelty gadgets powered by a AA battery that have hall-triggered pendulums too.

And I've seen a blog of someone who hacked a PC fan motor (which has the hall device and driver ic etc) to make an electronic pendulum.

It might not be exactly what you needed but even if you need higher power it should drive a hbridge IC.
 

Mr. Arkham

New Member
Over unity does not exist as far as I know.

I am attempting to recreate a mag-lev effect such as seen in roller coasters; but on a small scale. Purely for my own enjoyment.
 
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