19-06-2019, 08:13 PM
Hi Bob
I have "played" with both Austin Sevens and Arduino based systems. Must make me a minority of a minority ! I doubt if a 5 gram imbalance at such a small radius will have any detrimental effect. However, using two magnets will of course double the pulse rate and allow you to measure RPM with less need for smoothing. You will need a good magnet adhesive to withstand heat and vibration.
Given the fairly low speed of camshafts and propshafts, you might consider measuring RPM indirectly, i.e. by measuring the time interval between shaft pulses (gate a fairly fast clock and count the clock pulses) and then calculating the reciprocal. This "reciprocal counting" gives a much quicker responding measurement of RPM with good resolution. Apologies if you have already thought of this.
Let us know how you get on
Cheers, John
I have "played" with both Austin Sevens and Arduino based systems. Must make me a minority of a minority ! I doubt if a 5 gram imbalance at such a small radius will have any detrimental effect. However, using two magnets will of course double the pulse rate and allow you to measure RPM with less need for smoothing. You will need a good magnet adhesive to withstand heat and vibration.
Given the fairly low speed of camshafts and propshafts, you might consider measuring RPM indirectly, i.e. by measuring the time interval between shaft pulses (gate a fairly fast clock and count the clock pulses) and then calculating the reciprocal. This "reciprocal counting" gives a much quicker responding measurement of RPM with good resolution. Apologies if you have already thought of this.
Let us know how you get on
Cheers, John