powering a tachometer with hall sensor?

Hi, It depends which type of tacho it is RVI or RVC. RVI may work but could be erratic, RVC should be OK as they work better with electronic ignition. There are conversion circuits available on an auction site near you. Some OEM tacho's work off a terminal on the back of the alternator.

Colin

Glen

What you suggest is possible, but its a very broad question akin to "There must be some way of putting that engine in that car..."

It very much depends on what you already have. However, if what you have is simply counting pulses, then hall sensor and magnets will give you pulses. Your sticking point is that an ignition-led tacho counts however many cylinders per rotation. You need to emulate that with magnets and get sensors that are sharp enough in response to give a pulse your tacho can read. That involves maffematics and fancy pants equipment.

My advice would be to simply get a little pack of neodymium magnets and a hall sensor from fleabay, glue a magnet to the chuck of a drill, and bench test your idea. If nothing else it will be fun.

Buy this:

www.ebay.co.uk/itm/A3144-3144E-OH3144-Y3144-Hall-Effect-Sensor-ICs-Magnetic-Detector-Arduino-PI-UK-/252939722658?var=&hash=item3ae461dfa2:m:mQ7nZCm1tbzzzV--SA8AlEA

And this:

www.ebay.co.uk/itm/20mm-x-4mm-Very-Strong-Rare-Earth-NdFeb-Large-Neo-Neodymium-Disc-Round-Magnet-/191888257091?var=&hash=item2cad6e7043:m:mP9kVYgF_YspfeypEe61glQ

Wire it up like this:



(but with 12v not 5v. May work without the resistor, I dunno, try both).

Stick a magnet to a drill chuck.
Put the chuck next to the sensor.
Put the output of the sensor to your rev counter.
Spin the drill.

If it works, ace! You need two magnets VERY FIRMLY glued to your crank or four on your cam.
If it doesn't work, you've lost a couple of quid and learned something.

They were the first magnets I found.

These are smaller

m.ebay.co.uk/itm/Tiny-Magnets-3x2-mm-Neodymium-Disc-small-round-neo-craft-magnet-3mm-dia-x-2mm-/152088028951?var=&hash=item2369272717%3Am%3AmcRs-pIjxi9loeW3wBWW-GQ&_trkparms=pageci%253Ad16a9a62-93ce-11e7-96c9-74dbd180d824%257Cparentrq%253A5c7c76b215e0aa12e9cf8667ffef2ff4%257Ciid%253A7

As for the sensor, yes that's the same sort of thing just in a case. Seems a shame to spend so much on a proof of concept if it turns out to not work though, hence the suggested component. With amazon though returns are easy if it don't work.

Do report back and let me know how you get on. More than happy to help!

Ah. What's the rated voltage of the sensor?

Tried changing wires around, no success, running with
Red+
Black-
Blue=signal
The signal voltage fluctuates between 9 and 5 volts.
So it looks like the sensor has failed, will look at getting another one then trying again
Ttfn Glenn

Did it come with instructions? Is there a shunt resistor built in to the housing?

"Detect Object : Iron; "

Will that work for you?