Peeps, I have an Acewell unit that came with a magnet and reed switch. Not wanting to use that I've been trying all day to get this to work.

Its a hall effect senor off a Perjoe, it was looking at the starter ring on the bell housing so presume it was fro the ign?

Anyway, wiring it up to my Acewell today, allen key in the drill, woosh 240mph! However, fastening onto the car so it looks at the diff bolts i get nothing 0.00mph

The output from the dash is only at 3.5V so will that reduce the effectiveness of the sensor?? I cant get it any bloody closer

Thoughts please peeps....
Rescued attachment speedo.jpg

I tried a Ford VR sensor on an Acwell and could not get it to work properly.


The read switch worked fine however.

just been perusing the acewell site and came across this statement:

"The ACEWELL speedos are available with the following types of speed sensor as follows:

Sensors can be bought as replacement parts for £14.95 each. The part number in the speedo must be underlined to be able to work with hall effect and mechanical drive speedos"

What does it mean were it says The part number in the speedo must be underlined to be able to work with hall effect

If it is realy a Hall effect sensor that isn't going to work unless you can magentise the prop bolts. Hall effect detects magentic fields.


If it is a relucatance type sensor - these have a magnet built in with a coil around the magnet - a ferrous object passing close by - say a steel prop bolt - will "distort" the magnetic filed generating voltage in nthe coil.

I have no idea what that sensor you have is - it may be neither of the two I have described.

A hall effect type sensor would have 3 wires live, neutral and output.If your sensor has just 2 it is a magnetic reluctance sensor and will generate an output of varying voltage depending on the speed of the target it is aimed at.
What you probably need is a 3 wire proximity switch which will give an output when near a ferrous object that is moving or stationary.RS sell them in various sizes something like an 8mm thread woud do the job.
Paul.

The sensor itself is magnetic, it sticks to the bolt heads and picks up filings etc. Doesnt work in position on the car but whizzing the allen in drill past it gives me a display. I'm wondering whether the input voltage at 3.5V is too low.

I get the drift on what your saying there Paul. The sensor has two wires that connect to the Acewell, it supplys 3.5v to my two sensor.

From what your saying there i believe now it needs a good speed to pick anything up, hence the 240 mph on the drill!

Back to the supplied magnet and pickup me thinks.

What I was looking for was a locost solution for a robust speed sensor setup.

Cheers,
Steve

Ive had a cycle speedo fitted for over 2 years and had no problem with the sensor which is just a reed switch and magnet type.I mounted the sensor with the supplied O rings and securely cable tied the cable to the wing stay so as it didnt put any strain on the sensor.For the magnet I got a small magnet and glued it to the wheel rim with epoxy resin.
Paul.

If the sensor is magnetic then it's a VR (variable reluctance) sensor (like crank position or ABS wheel sensors) not a Hall effect. It should not be supplied with a voltage as it produces it's own when metal objects pass nearby. These sensors produce an AC output voltage which is then 'decoded' by a processing circuit to produce a pulsed output that can be used by an instrument / ECU.

The fact you got a reading with the drill sounds like luck, it isn't the right sensor to use and you won't get a reliable reading from the gauge. You need to get a proper hall-effect sensor or reed switch and put a magnet on the prop flange.

I went with magnets and reed switch, four magnets araldited to the prop flange, simple and no problemd