A little help with a Proximity sensor and a RPM gauge

Alexanderfitu said:

I was thinking, they would be a bit rubbish if they ended being magnetised together, could happen I suppose

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It did happen and yes, the reed switch probably was rubbish (I've no idea what brand it was)!

The VDO tacho on Ebay is very simmilar to the one I used & it came of a large diesel generator. The engine orig had a small ac generator run of the camshaft to drive the tacho. I removed the internal circuitry of the tacho & just used it as a meter driven by the freq to voltage converter. This worked very well on my diesel boat motor.

I do suspect they only make one type.

Any idea what sort of signal they are designed to run on originally, I may just copy the schematic you posted if it ends up being the same gauge.

Would that work for the sensor I posted?

Would that work for the sensor I posted?

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Yes, and you would configure it exactly as debe did his sensor.

Ron

To drive the hall i used a small magnet out of a scraped signal level meter, If its glued to the engine shaft as in picture it will give a Nth then a Sth pole presented to the hall switch. The hall requires this to turn it on then off. Using one magnet it is easy to calibrate as in my early pictures using a small solenoid to drive the hall. Here the mains is 50Hz & gives a reading of 3000Rpm

This is the data sheet for your series of sensors. Something to note here is where the data sheet shows "South Pole-sensitive Switch or Bipolar Latch Available ". The sensor bebe used was a bi polar latch and thus he uses both poles. The N pole latches and the S pole unlatches to create his pulse. This would be the same as the MP101303 in the data sheet. If you use the MP101301 or MP101302 you only need the sensor to see the S pole and each time the S pole passes a pulse is generated.

Ron

Hi Ron, Thanks for the extra input on the diferent types of Hall devices. Daryl. All my Hall devices were salvaged from scraped VCRs for free, they were used as reel sensors.