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4 digit rpm meter


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I bought one of these from ebay a few months ago to read rpm on the mill (I know I know). There's no wiring diagram for the display just a bit of Chinese writing (ok I know I know!).

I did a bit of Internet searching and wired it up the most common way;

Pin 1: +ve supply and +ve sensor

Pin 2: -ve supply and -ve sensor

Pin 3:

Pin 4:

Pin 5: signal from sensor.

With pin 5 disconnected the display shows 0000 rpm and the sensor led flashes as the magnet passes.

With pin 5 connected the display shows ---- and the sensor led is on permenantly. I have tried a 10k pull up resistor but it doesn't like that.

I have uploaded a video here https://youtu.be/sHQyfbibadQ

Any advice from electrical people? I have contacted the seller but I doubt I will get much back ad I've had it ages. Is it a dud or am I just doing something stupid. It shouldn't be this hard!

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I think it's nic-nakked!

Annoting thing is I've wired that gauge every which way I could think of trying to get it to work, if I'd wired it straight into the mill it would've had a clean dc supply and worked first time. :/

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