Hall effect sensor

[millsd60]

Anyone any idea how Hall effect sensors work?

My gearbox is from a 1985 XJS (Getrag) and it has what I think is a Hall effect sensor on the side of it. I have connected the wires on my Speedo (Smiths CA) to it but get no Speedo reading at all.

So what am I doing wrong? Is it a Hall effect sensor on my gearbox? Or is the Hall effect sensor some other beast that I don’t have?

I have connected the green wire of the Speedo to +
The black wire to earth.
The Green/purple wire to 8volt to one of the Hall effect wires
The White/black wire to Hall effects other wire.

All as per the instructions…but no dammed go…..!
:} :v

[StuartH]

Sounds like a hall effect sensor (enough wires), if the sensor is ok it may need a pull-up resistor to make it switch between +ve and ground because many are "open collector" outputs which switch between ground and open circuit.

Stuart

[Dan]

The only other possibility is that it is for your reverse lamp, Run a multimeter over it and check if a connection is made in and out of reverse...


Dan ~ http://homepage.ntlworld.com/danny.mann/

http://images.animfactory.com/animat...ood_md_wht.gif

[ian]

Hi Dave, I also have a Getrag from an XJS 6 cylinder, mine is from about 1987/8 I think.

It has two screw-in switches on the passenger side of the casing (my car is right-hand drive.) The one nearest the front is for the reverse light, the other one I'm not 100% sure about but I have seen it described as a 'first/second gear switch.' I am 99.99% certain that these boxes have no speedo drive at all, neither mechanical or electronic. On the donor car there is a transponder near one of the rear drive shafts which picks up a signal from a rotating set of magnets (or similar) which is then sent off to the speedo. If you unscrew both switches you'll see they are very similar, a kind of plunger job. If yours does actually have a speedo drive aswell as these two switches please tell me where it fits, I may be able to add one to mine. I am about to blow a couple of hundred quid with Gower Oaks (if they ever answer the phone or my recorded messages) on converting my mechanical Smiths XJ12 speedo to electronic plus the matching remote transponder which can be set up to operate from the propshaft rear flange. Where did you get your speedo from?
Good luck. Ian

[russell_ram]

Ian,

you are absolutely correct about the XJS speedo drive. The electronic speedo pick-up is mounted in the aluminium diff cover just below the breather. It picks up it's signal from the diff carrier which either has machined 'notches' in it's outer diameter or has a pressed on steel ring with the same features (depending on the age of the diff). I would think it should be much easier to use this existing pick-up than to try to fabricate a prop or gearbox pick-up. I'll be doing exactly the same as you when I get round to it, but using the existing Jag sensor, because my (brand new Smiths) mechanical speedo is cr*p!


Russ

[millsd60]

Ian

I am convinced mine is a Hall effect sensor. If I unscrew it, there is a square section shaft about 1/8" diameter coming out of the gearbox. The shaft drives into a cylinder shaped unit about 1 1/2" diameter with two wire coming out. I'll tell you what...I'll take a snap of it and publish it.........

[millsd60]

Guys

Just taken a photo of what I think is my Hall Effect sensor.....

http://www.cobra-replica.co.uk/crcfo...files/1457.jpg

Any thoughts?

[ian]

Dave,

well I'll have to eat my hat won't I!! Mine has nothing like this. How far back on the gearbox casing is it? About 3 or 4 inches behind the reverse light switch and towards the top vertical edge of the casting I have a circular recess/boss which is unused. I wonder if that was where they originally positioned the Hall Effect sensor?
I think I'm going to have to go with the solution I mentioned earlier.
Hope you get yours sorted. Ian

[ian]

BTW Russ, when I spoke to Gower Oaks a while back they quoted 35 quid or so for the remote sensor/bracket setup. From memory I think you have to screw or rivet the sensor mounting bracket to the chassis somewhere near something that rotates relative to road speed eg propshaft flange, wheel etc. The magnetic 'triggers' are then stuck onto the rotating item and the sensor positioned close enough to pick up the signal. I know of other Cobra/Getrag users who have gone this route with some success although sensor positioning is important if the speedo is to behave properly. Ian

[millsd60]

Ian

Just goes to show doesn't it....Jaguar probably never made two cars the same....

The hall effect sensor on mine is on the left side of the box (looking from prop shaft end) about 6" from the prop shaft input spline.

I am now thinking of getting one of the magnetic sensor type senders for the Smiths CA speedo, and mounting the magents on the prop shaft. (Got the Speedo from Andy at GDs by the way).

Has anyone succcesfully done the magnetic sensor route with a Smiths CA Speedo?
If so, what colour wires on the Speedo go where. And which is the best magent sensor to go for?
And has any one any photos of how they fitted it....!