> Hi Robert et al!
>
> The one you have could be exchanged for a more up to
> date one, even Radio Shack has them.
>
> Here are excerpts from http://www.deja.com search for
> Hall Effect switches;
>
> Digikey carries Cherry, Micronas and Panasonic Hall
> sensors. Also check Sprague (now Allegro/owned by
> Sanken of Japan) http://www.allegromicro.com
>
> They have 3 connections- +, gnd and output.
>
> For more info, look for Allegro data. They make a
> whole range of Hall devices, and their data sheets and
> applications notes are excellent.
>
> Try a web search. Be sure to use the term "Hall
> Effect Switch" rather than simply "Hall Effect" (to
> avoid the analog, magnetic field measurement type
> devices).
>
> Look for familiar names like "Microswitch" and other
> well known keyboard suppliers, since they are the
> quantity consumers of these devices and, for the
> reason, may also be the key producers and suppliers to
> the OEM market.
> ----------------------------
> How a Hall Effect Switch (sensor) works;
>
> A current flowing through a conductor passing through
> a magnetic field encounters a force that pushes
> perpendicular to the current and perpendicular to the
> field (the force is determined by the cross product of
> the two vectors).
>
> This force acts on the current itself, and it is the
> force that we use to do such things as make motors
> spin. In this common context, the current is confined
> within thin conductors (wires!).
>
> In the Hall effect, you take a broad conductor and let
> a current flow from one end to the other. If there is
> a magnetic field perpendicular to the plane of the
> conductor, it will push the current over to one side,
> and this will give you a side-to-side voltage across
> the conductor. This was discovered by Mr. Hall, hence
> the name.
>
> In a Hall effect sensor, you provide a constant
> current between two terminals and the voltage is
> measured across the other two terminals. I believe
> that some hall effect sensors contain integrated
> constant current sources; I know that some Hall effect
> sensors have only three terminals, power, ground and
> sense. The voltage from ground to sense is the Hall
> effect voltage. Finally, some Hall effect sensors
> include an amplifier, so that the sense output isn't a
> tiny voltage linearly related to the field, but is
> large and nonlinear. For example, there are Hall
> effect sensors with TTL outputs that switch on when
> the field exceeds some threshold and switch off when
> the field falls below some other threshold -- the
> built-in hysteresis is because there's a schmidt
> trigger built into the output circuitry.
>
> > Does it have polarity?
>
> The basic 4-terminal Hall effect device, with no
> on-board electronics, has no polarity. If there's a
> built-in output amplifier or a built-in current
> source, there will definitely be a polarity.
>
> > Which manufacturer makes such a component?
>
> Allegro semiconductor makes a large selection. They
> have a web page, I think it's http://www.allegro.com
> or something equally commonplace.
>
>
> --- Robert <billc9@prysm.net> wrote:
> > Hello All, I need help with understanding the
> > schematic at John's website. Address is
> > http://www.nidlink.com/~john1/idea.html
> > Its the Adams type test motor for energy recovery.
> > At the Hall switch 3020T in the schematic, there is
> > 1,2,3 for connecting the wiring to the switch. The
> > Hall 3020T switch is not available anymore. Its a
> > magnetic type switch, but is 1 com?, 2,NC, 3, NO??
> > Or is it set up completely different from that
> > style. I need to change from a manual switch to this
> > setup. The manual switch is taking a beating and
> > very noisy. I have all the needed parts to build '
> > this setup except the Hall switch. Will a 10 watt
> > magnetic reed switch work? If so how should it be
> > wired in? I can easily convert this using a
> > different plastic washer with magnets secured to it,
>
> > to activate the switch. I just dont want to burn
> > every part on the board up by hooking it up wrong.
> > Any help?? Regards, Robert
>
>
>
> =====
>
>
> =================================
> Please respond to jdecker@keelynet.com
> as I am writing from my work email of
> jwdatwork@yahoo.com.........thanks!
> =================================
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