Blaze EMS 2 - Hall Effect Sensor - Jabiru

[timodlin]

Hello

I have just installed a Blaze EMS 2 on my Escapade with Jabiru 2200A. The unit replaces the Stratomaster E1 which was working fine but black and white display was becoming difficult to read.

CHT probes and T&P's all seem to be working as they should. As recommended and supplied with the unit by the UK distributor, I have installed a hall effect sensor for RPM/tacho to pick up the flywheel magnets. It has been installed in accordance with the wiring diagrams and also jabiru manual recommendations for hall effect sensors. I have also been through the settings and set pulses per Rev at 2 (for jabiru 2200 engine).

I getting completely erratic and unstable RPM values. I have tried various pulse per rev settings and increments etc.

Can anyone help please?

[Russ_H]

Uncanny, I just joined this forum to try get help with exactly the same problem. Only difference being my unit has worked fine for over 2 years but suddenly exhibits this erratic behaviour, Ive been through adjusting sensitivity, checking all wiring and anything that could be causing interference and changing out the hall sensor, looking like its something unit itself.

[timodlin]

Hello Russ

I have tried mine again tonight still very erratic. It sounds like yours was working properly and stable for a while. What sensor have you used?
I have just bought another sensor to try - NJK-5002C. I saw that others have used this sensor.

The distributor said that the pulse revs for the jabiru should be set to 4 because there are 2 flywheel magnets, both with positive and negative. I tried this today and got what I would consider more realistic rpm values but still totally erratic. Also played with sensitivity but this didn't seem to do much.

[Russ_H]

Tim, I used that same sensor. Yes Mine has always been set to 4 pulses per revolution. there is an led on back of the sensor that will light up when a pole passes which gives a good check for function, my sensor is set about 6mmm away and points at the face of the flywheel magnets not the edge of the flywheel.
Im still chasing my problem, but latest thing I tried was new battery for the internal clock, figuring the clock must be essential for it to compute rpm from pulses.
I hope to give it a ground run tomorrow

[timodlin]

Hello Russ, I am going to the airfield today to try a couple of things and possibly the new sensor. thanks for the clarification on the pulses per rev. I will let you know if I have any luck. good lick with yours

[timodlin]

Hello Russ, I tried the new sensor today but still not working properly. Really frustrating. I am sure I have wired everything as it should be wired. Did you get anywhere today?

[Russ_H]

Sent you a PM Tim

[Russ_H]

Got nowhere with this, tried different sensors checked all wiring even a different reg/rectifier, cant find any bad RF (radio is good and ignition components fairly low hours magnecor leads and resistor plugs)

[rainier]

Did you install a hall-effect sensor or is it just a passive coil ? If it is a hall effect sensor you will be supplying ground and power to it. If it's just two wires all you have there is a coil. I suspect this is what you have.
A small voltage is induced as the magnet goes past.
You set the number of pulses to 2 if a magnet passes the coil twice per revolution. That's it. Don't try and solve an incorrect reading by "tweaking" that number.
On the EMS-2 make sure the high frequency filter is OFF (dipswitch). The pulse is very short in duration an this filter will reduce the voltage the EMS-2 sees if it is "ON".
Now you need to get that pulse voltage as high as possible. The voltage changes to the square of the distance to the magnet. This means a small change has a big effect. Adjust the gap to be as small as possible to get the highest possible voltage.
Now turn the sensitivity trimmer on the back of the EMS-2 to maximum sensitivity.

You need a voltage of a few volts peak to peak (it actually is an AC signal). If in doubt, beg, borrow or steal an oscilloscope to see what the pulse looks like.

A hall effect sensor is an active device and will give you a big and clean signal - in most cases you will need a pull-up resistor on the output. Something like a 2200 ohm or such to 12V gives you a "fat" 12V pulse. More than enough for the EMS-2.

[Russ_H]

Hello Rainer, as stated we both have Hall effect sensors fitted with appropriate pull up resistors not coils (3 wires Power-Gnd-Signal)

Can I assume the advice you give suggesting turning off the filter is applicable to a coil (solenoid?) sensor that may not give enough signal strength and NOT applicable to a hall effect sensor with a 12 volt supply?
Thanks, Russ