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Speedo prop sensor
andyhaase1 - 11/6/18 at 03:21 PM

Hi, Iíve bought some glowshift gauges (USA)for my MNR build, and I thought I could run it from my mark3 mx5 gearbox. However, it seems these gearboxes donít have a speedo take off, so now I presume I need to fit something that will read the propshaft . Glowshift say they only do a gps sensor, and thatís not acceptable for IVA.
Can anyone shed any light on this please.
Andy


gremlin1234 - 11/6/18 at 04:12 PM

a quick look at
http://glowshift.com/instructions/Accessories/7-8-18-Mechanical-Speedometer-Adapter.pdf

suggests their sensor for the mechanical take off is just a hall sensor, (switching to ground)
and the green wire on the speedo being the sense input.

edit:
http://www.glowshift.com/instructions/7-Color-Series/GS-717_speedometer334.pdf
shows this is the 'normal' operation of the units!

[Edited on 11/6/18 by gremlin1234]


andyhaase1 - 11/6/18 at 08:14 PM

Thanks for the reply,
I did an online chat with them today, they basically said they couldnt help.
So, what do I need to make this speedo work, The mx5 mark3 gearbox speed sensor reads off the abs trigger wheel I believe, which I dont have.
Will this work?

https://www.healtech-electronics.com/wp-content/uploads/SpeedoHealer_v4_with_harness_kit.jpg

Andy


gremlin1234 - 11/6/18 at 08:39 PM

quote:
Originally posted by andyhaase1
Thanks for the reply,
I did an online chat with them today, they basically said they couldnt help.
So, what do I need to make this speedo work, The mx5 mark3 gearbox speed sensor reads off the abs trigger wheel I believe, which I dont have.
Will this work?

https://www.healtech-electronics.com/wp-content/uploads/SpeedoHealer_v4_with_harness_kit.jpg

Andy

no the speedhealer wont help. (well not yet anyway...)

you need a magnet on the prop, and a sensor for that.
this type of thing
https://www.demon-tweeks.co.uk/motorsport/data-logging-sensors-cables-accessories/aim-motorsport-wheel-speed-sensor-pick-up-magnetic-or-hall-effect-op tion


andyhaase1 - 11/6/18 at 08:57 PM

Ok, funnily enough Iíd just googled magnetic sensors and that demon tweeks page was the top hit.
So does it matter wether I get a magnetic or hall sensor?


gremlin1234 - 11/6/18 at 09:11 PM

hall effect are magnetic sensors.

technically, you could use a reed switch, but thats 'old technology'


SteveWalker - 11/6/18 at 09:14 PM

Hall effect is a magnetic sensor, but an electronic one, rather than a reed switch. I use a proximity sensor, mounted so as to count the propshaft bolt heads (at the diff end), without any magnets.

Once you can work out the pulses per mile, I presume that your gauges can be configured for that (as my Caerbont speedo can).

Sorry, but I can't give you any part numbers - it was fitted 19 years ago!

SteveW

[Edited on 11/6/18 by SteveWalker]


andyhaase1 - 11/6/18 at 09:17 PM

Thatís fine, Iíll order the Hall effect one from Demon Tweeks.
Cheers for the help.


gremlin1234 - 11/6/18 at 09:25 PM

quote:
Originally posted by SteveWalker
Hall effect is a magnetic sensor, but an electronic one, rather than a reed switch. I use a hall effect sensor, mounted so as to count the propshaft bolt heads (at the diff end), without any magnets.
yes there are many types of hall sensor, some that 'induce' a magnetic field (often the abs sensor type), and some where they use an external magnet.


SteveWalker - 11/6/18 at 09:34 PM

I've just edited my previous post before finding that it had been quoted - I changed "hall-effect" to "proximity" - to cover the fact that it is the type that works without a magnet.


02GF74 - 12/6/18 at 05:38 PM

quote:
Originally posted by SteveWalker
Hall effect is a magnetic sensor, but an electronic one, rather than a reed switch.


Technically a Reed switch is not a sensor. It is a switch whose contacts are closed by bringing a magnet near it.

Hall effect sensor will give a signal proportional to the stroof the magnetic field.

If the gauge needs a signal switched to earth, you can test it by running a wire over a metal come to produce rapid pulses, then reed switch will work. Downside is they have max number of open/close cycles, many millions, but will eventually fail.

Hall sensor will outlast reed but you will need some a means to switch the gauge to earth, requires nothing more complex than a single transistor stage.


02GF74 - 12/6/18 at 05:43 PM

quote:
Originally posted by gremlin1234
quote:
Originally posted by SteveWalker
Hall effect is a magnetic sensor, but an electronic one, rather than a reed switch. I use a hall effect sensor, mounted so as to count the propshaft bolt heads (at the diff end), without any magnets.
yes there are many types of hall sensor, some that 'induce' a magnetic field (often the abs sensor type), and some where they use an external magnet.

.

I may be wrong but I don't believe those are hall effect.

They work by having a coil around a magnet, bringing an iron object disturbs the magnetic field inducing a voltage in the coil. They do not require a power supply wherea's Hall effect does at it is semiconductor device usually with a built amplifier.


MikeRJ - 13/6/18 at 11:49 AM

quote:
Originally posted by 02GF74
quote:
Originally posted by gremlin1234
quote:
Originally posted by SteveWalker
Hall effect is a magnetic sensor, but an electronic one, rather than a reed switch. I use a hall effect sensor, mounted so as to count the propshaft bolt heads (at the diff end), without any magnets.
yes there are many types of hall sensor, some that 'induce' a magnetic field (often the abs sensor type), and some where they use an external magnet.

.

I may be wrong but I don't believe those are hall effect.

They work by having a coil around a magnet, bringing an iron object disturbs the magnetic field inducing a voltage in the coil. They do not require a power supply wherea's Hall effect does at it is semiconductor device usually with a built amplifier.


You are thinking of a variable reluctance sensor, most often used for ABS and crank position sensors. You can also get "biased hall sensors" which is a hall sensor with an embedded magnet that are sometimes used for the same jobs and more often used for cam sensing.

A biased hall sensor is easier to interface to because the output voltage does not change they the speed of the object they are detecting, which also means they can detect very slow moving parts. The downsides are that they need a power supply (such sensor will usually have at least three wires rather than two for the VR sensors) and they can be a little less robust since it's a semiconductor circuit rather than just a coil of wire.