Gordon

Have a look here…..http://www.ebay.co.uk/itm/Red-LED-Tachometer-RPM-Speed-Meter-with-Proximity-Switch-Sensor-NPN-UK-SELLER-/181892033370?hash=item2a599c2b5a

Looking at the rear of the tacho,(pcb side) the white connector numbered 1-5 left to right…

1) 12v dc positive supply

2) 12v dc ground

3) Signal input

4) No connection

5) Test +

the probe wires connect:

Brown-terminal1

Blue- terminal 3

Black- terminal 5

Info offered on an as is basis, no responsibilty for blowing it up…

Hope this helps…..

Gordon.

Just by coincidence I received one of these this morning from Hong Kong. Spent some time trying to work out the wiring , with no luck. When I came in for lunch I saw John's reply. When I wired mine up as John's ( Apart from I think he meant BLUE OF THE SENSOR TO TERMINAL 2 Ve Gnd ) info. it worked o/k.

Terminal 1 +ve to display and sensor (brown)

Terminal 2 -ve to display and sensor (blue)

Terminal 5 input from sensor (black)

Terminal 3 & 4 not used

That's how it is on mine.

PS just checked Terminal 2 & 3 on mine are communed together so are both -Ve in. So John's info is correct.

Ian

Gordon. Len must have pressed "add posting" while I was still composing my post

Any way pleased you are up & running.

Ian

Interesting to see that there is another way to wire it up than the one I used.

I got some info from here:

**LINK**

(note spelling mistake so cut & paste)

and some more from here:

**LINK**

The wiring is marked on the PCB. With the connector on the bottom, the 5 pins are left to right

1 2 3 4 5

[Sensor Power +5V] [Sensor O/P] [Sensor GND] [Supply +12V] [Supply GND]

Ignore the dot, dashes and plus signs on the cable as they are different on all the ones I’ve seen.

My version is :

1 2 3 4 5

Sensor O/P not used not used Supply +12VDC Supply GND

This may be wrong as there is a small plus sign on the right of the characters on pins 1 & 5 or is that part of the character? Anyway mine work ok.

On the 5002C Hall Effect Proximity Detector I also have two wiring versions from the small label on them, one shows

a pull-up resistor to positive and the other to negative, I used a 220 Ohm resistor to positive.

I am using a Regulated 12VDC 0.5A power adaptor .

The Sensor is polarity conscious so get the magnet the right way round. I have used a bigger countersunk magnet on the Myford and screwed it on the pulley in one of the balancing holes (Oops!) and the one on the VMC Mill just relies on the magnetism as it sits in the recess under the spindle pulley so can’y fly off at speed. There is a screwhead down behind the pulley on the Myford so the magnet and retaining screw need to be slim to miss this.

I have put a variable speed setup on my Myford so no longer know what rpm it is running at and needed a way to monitor this so I put the magnet on the pulley inside the casing so this only indicates the direct drive

RPM so I will have to do a calculation to show what the direct drive RPM should be when running via the

back gears, I couldn’t think of a way to monitor the spindle directly so had to use this method for now.

I have added some photos in my Albums under "4 Digit Tacho" if you want to see a scruffy installation but it does work.

Hi Gordon, I used a small dab of silicone sealant to fix my magnet to the rear of the lathe spindle then left overnight to set. It has remained firmly in place for about 18 months now, resisting the urge to break free at occasional speeds in excess of 1500 rpm. I initially used a blob of blue tak and very slow rpm to test it and found by accident that there seems to be a right and a wrong side of the magnet to present to the face of the sensor, so if you find it initially doesn't read, try flipping the magnet over!

Martin.

There seems no consitancy to the wiring….but my description is as per the sketch in the ebay link I gave and marries up with that posted by the merry miller…

Oh and yes the probes are polarity sensitive to the magnet….as you guys have found out…

Electronics is fun….well at times is is when everything works as anticipated…

Len, hope you get sorted…

Edited By John Rudd on 13/11/2015 19:03:20

Are these things worth bothering with? I DIY'd one a few years back, but never bothered with a permanent install as it felt like an ornament rather than adding any value.

Steve

Just thought I would show how I mounted the sensor & magnet on my ML7R this morning,

Ian

There ate thousands of these on eBay, mostly the same module, quite a lot do include a wiring diagram in the listing.

It is not rocket science, 

On mine, when power attached does a self test and comes up with a code on the display before resetting to all zeros.

It will work on any voltage from 5v, not sure of max but plenty high enough, I just used a 9 v wall wart – half an amp should be more than enough.

Hall effect sensors are polarity specific, the magnet to sensor will only work one way, if the sensor light does not come on, just turn the magnet round.

The magnets supplied are very strong super magnets, mine is attached to the mill spindle just by its magnetism, mill will go to 2500 rpm, has not come off yet and highly unlikely to.

With regards to non working units, just let eBay know if you can't contact seller ( I have had no problems with contacting Chinese sellers and Will usually just send you a new one – they do NOT want any negative feedback so you should not have a problem getting a replacement.

I now see how the thing is connected up apart from one thing. Some people have the set up working without a pull up resistor from the black lead on the sensor to the positive power connector, so should the resistor be included or not?

Doug

This the one I have just ordered..

**LINK**

Len.P