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ADC Alt CAM, Alt CRANK RC filter
Posted: Wed Apr 11, 2018 5:01 pm
by maximus64
On Frankenso schematic, ADC section for ALT CAM and ALT CRANK have a label that said "low pass filter knee at 100kHz typical". Is the 10K before the diode clamp take into account? I don't think it correct, base on my calculation it should have a cutoff at around 1.5kHz not 100KHz. Is this too much filtering for trigger input? I'm using this input for NA8 Miata CAS input.
Re: ADC Alt CAM, Alt CRANK RC filter
Posted: Wed Apr 11, 2018 5:08 pm
by kb1gtt
The LPF is only for R313 and C310, filtering caused by external caps, and the influence of R312 are not included in that schematic note.
Required frequency is dependent on your crank wheel. More teeth needs more Hz, as well faster RPM's needs more Hz.
Re: ADC Alt CAM, Alt CRANK RC filter
Posted: Thu Apr 12, 2018 7:46 pm
by AndreyB
I am not sure if any miata runs on op-amps
Re: ADC Alt CAM, Alt CRANK RC filter
Posted: Sat Apr 14, 2018 8:17 am
by RadMx5
My does work on op-amps
Both Cam and Crank
Just having some issues above 6500RPM. I have still not found the source of the problem. It could be to do with filtering as you say "maximus64"
For now I'm waiting for another engine... As my current engine started to burn oil...
maximus64 - if you want there is some info here:
https://rusefi.com/forum/viewtopic.php?f=3&t=1282