Frequency input

Ed Schippers 8 years ago updated by Rick Yorke 4 years ago 8

Is it possible to use Frequency input to get the engine speed by using the W contact of the alternator?

Satisfaction mark by Ed Schippers 8 years ago

I have never tried it, but there are are two main issues I can think of:

-The FIN trig levels, where the amplitude of the signal mus be so that it is low <1 V and high >4V

-The FIN does not cope with negative voltages very well, with voltage < 0 V, it could get damaged.

Searching answer

There might be a possibility. The XC10 has got two AC coupled frequency inputs, perhaps that could be used.



The XC10's AC frequency input will work with an alternators frequency output. There will need to be a minimum 5v peak to peak signal. This input is sensitive to noise, so if the alternators signal is noisy it will affect the frequency reading.


This works perfect

To prevent a negative voltage on the input i used a diode

PS. the engine was a Hatz 1D81 (flywheel alternator)

I'd like to do this exact same thing with the XC10's AC coupled FIN's.

Does -vref need to go to the alternator's negative terminal or be involved in any way?

Also, is the diode really necessary since this FIN is meant for AC?

Provided that the XC10 is grounded to battery/chassis, you should not need to ground directly to the alternator. I would expect that the alternator ground is at the same level as negative battery.

The use of the diode was to clamp the level above 0v, to avoid risk of damaging the input. If the frequency has a positive DC offset and the input will not see a negative voltage the diode is not required.