I have MGL flight2 and E1 instruments.
I've ran out of variants to connect them to get stable RPM readings. Please help.
I have 2 stroke kawasaki TA 440B engine.
I use 12v lipo battery that is not connected to engine lightening coil (no charging). battery negative pole is connected to engine block and to frame. +12 to instruments and to starter through solenoid.
Engine original scheme:
I've tried to connect RPM readings to kill (Nr. 1 on scheme) switch wire through 10kOmh resistor;
to ignition coil low voltage side through 10kOmh resistor
to pulser coil through 10kOmh resistor.
I've always got unstable and incorrect readings. They were way too high on high rpm and very unstable (and 300-600 rpm higher)
no matter what sensitivity settings on the rear instrument knob.
SO after many attempts i've decided to use hall sensor. I've glued 2 magnets to crankshaft pulley and used SS441A hall sensor.
The connection scheme is the same as shown in manual, except i use +12v from battery and 10kOmh resistor. (but i have tried also with +5v from instrument. result was the same.)
The results are +600-800 RPM higher and difference get bigger on higher RPM. But, the oscilloscope shows stable frequency readings.
When i select time readings, the instrument for ~1/2 second shows correct rpm, but then jumps to 2 to 4 higher readings. For example it shows 3000 rpm then randomly jumps to 6000 or 9000 or even 12000 rpm and so on.
It seams that i got some small pikes. But i cant understand WHY? I've battery connected to hall sensor and that's all. No magneto or generator is connected...
Why MGL instrument is not filtering small peaks? In my opinion the signal i see in oscilloscope is reasonably stable...
The last thing i have to try is to disconnect kill switch wire. It is unshielded an go's near RPM wire. May be it produces high and low peaks.
