Hi,

No, that does not work. You need a digital sensor, such as a hall effect sensor or an encoder. They should be of type open collector (sometimes called npn), since YourDyno has an internal pullup resistor.

Okay thanks. Like this one?

https://www.ebay.com/itm/Hall-Effect-Sensor-Proximity-Switch-NPN-3-wires-with-magnet-Normally-Open-N-X6M8/223137797373?epid=25012086485&_trkparms=ispr%3D1&hash=item33f40c94fd:g:FQ4AAOSwf2pblSQ0

Why I'm asking you about this is because l need a sensor in range of m4-m10 so it will fit the brake. so l can't use your sensor. 

Do you know where l can buy a good sensor ? 

That may work. You need one that triggers on ferrous materials (iron), since you need a trigger wheel, see wiki. Also the supply voltage is 5V, so make sure it works with 5V +/- a little bit.

Ok. I'm gonna use it inside the water brake as they do originally! It's a old dynamite 9" straight vane absorber.

If l remember correct it will be 12 teeth per revolution and the material is aluminum!  That should work? 

I think this one Will be perfect But do you know if l should use use no, nc or nc+no for the sensor? 

https://www.google.com/amp/s/m.aliexpress.com/item/2030055517.html

For that sensor I think the npn is the correct type. It was a bit hard to judge from the picture ;-). 

For the original sensor there must be magnets embedded in the aluminium, no sensor senses alu that I know of. But double check that it really is 12 of them. You should calculate the number of pulses per second, it should be minimum 200. For 12 triggers per revolution it means that it will work fine over 1000RPM. It works below too, but then you should turn off inertia compensation (normally not super important on an engine dyno). 

Alternatively you can do what we did on our water brake, we just added a trigger wheel and the standard RPM sensor. You can see it in the water brake videos in our youtube channel. 

Thanks.  I'm gonna read more about the sensors but I'm quite sure it will work on aluminum. I have seen a distance chart for another sensor with different kind of materials. and the maximum distance was way lower with aluminum than for steel. So it should work .

I have disassembled the brake so I'm going to check how many vanes it is before I'm put it back again. 

I'm going to try and see it it will work before I'm making a trigger wheel.

Or is it easier to use the engines rpm? 

No go for a hall sensor or an encoder for the brake RPM. 

BTW, how many pulses does your system expect per one turn of dyno shaft (in case of engine dyno configuration)?

Any number that ensures at least 200 pulses per sec at the lowest rpm of interest will work. More is good. 

So for example 15-20 or so. 

My water brake is connected at the gear box output and i run it in 4 th gear , so my rpm pickup will not read the engine rpm , how can i compensate it by software ?

thanks in advance

Fabrice

Hi, 

The RPM sensor should read the brake RPM. You do not need an engine RPM sensor, engine RPM is calculated from the brake RPM and the gear ratio. 

You can add an engine RPM sensor or use OBD2 in addition to the brake RPM sensor if you want. This will automatically calculate the gear ratio. All systems need a brake RPM sensor in any case, the brake RPM as the basis for all calculations. 

Glenn, that brake had a magnet in bedded in the aluminum for the original sensor.

 I looked at the brake and saw there  was holes in it for magnets. So I'm going to order some magnets. Thanks for saying that otherwise l had missed it 😂

Best regards 

Glenn